# Our Dynamic Universe

Save this PDF as:

Size: px
Start display at page:

## Transcription

1 North Berwick High School Department of Physics Higher Physics Unit 1 Section 3 Our Dynamic Universe Collisions and Explosions

2 Section 3 Collisions and Explosions Note Making Make a dictionary with the meanings of any new words. Momentum 1. State the formula and units for momentum. 2. State that momentum is a vector. 3. Explain what is meant by the principle of conservation of momentum. Momentum in collisions 1. Copy the five notes and both worked examples. Kinetic energy in collisions 1. Describe both types of collision and whether kinetic energy is conserved or not. 2. Copy question 7 on page 16 into your notes and find the solutions. Explosions 1. Explain why a gun has a recoil velocity. 2. Copy the worked example. Momentum and Newton s third law 1. Show that conservation of momentum and Newton s third law mean the same thing. Impulse 1. Show how impulse can be obtained from Newton s second law. 2. State the units of impulse. 3. State that impulse = area under a force time graph. 4. Copy the three worked examples.

3 Section 3 Collisions and Explosions Contents Content Statements... 1 Elastic and inelastic collisions... 2 Momentum... 2 Momentum in collisions... 3 Worked examples... 4 Kinetic energy in collisions... 6 A special case... 7 Explosions... 7 Worked example... 8 Momentum and Newton s third law... 9 Impulse Momentum and Newton s second law Worked examples Problems Solutions... 21

4 Content Statements content notes context a) Elastic and inelastic collisions. Conservation of momentum in one dimension and in which the objects may move in opposite directions. Kinetic energy in elastic and inelastic collisions. Investigations of conservation of momentum and energy. b) Explosions and Newton s Third Law. Conservation of momentum in explosions in one dimension only. Propulsion systems jet engines and rockets c) Impulse. Force-time graphs during contact of colliding objects. Impulse can be found from the area under a force-time graph. Investigating collisions using force sensors and dataloggers. Hammers and pile drivers. Car safety, crumple zones and air bags. 1

5 Elastic and inelastic collisions Momentum The phrase gathering momentum is used in everyday life to indicate that something or someone has got going and is likely to prove difficult to stop. There are echoes of this in sport, where the phrase the momentum has turned in the other team s favour can often be heard. In Physics momentum is an indication of how difficult it would be to stop something. The faster or more massive an object is the more momentum it will have. The precise definition of momentum is: The momentum (p) of any object is the product of its mass (m) and its velocity (v): p = mv Since mass is measured in kilograms and velocity in metres per second, the units of momentum are kgms 1. Momentum is a vector quantity, and the direction of the momentum is the same as the direction of the velocity. It is useful because it is a conserved quantity, i.e. the total momentum is the same before and after a collision, in the absence of external forces. This is called the principle of conservation of momentum. 2

6 Momentum in collisions Notes 1. You should learn the statement of the principle of conservation of momentum: the total quantity of momentum before a collision is the same as the total quantity of momentum after the collision in the absence of an external force. 2. This is a fundamental law of physics and applies to all collisions: road accidents, collisions between meteors and planets, collisions between atoms. 3. The law applies to total momentum of a system, not individual momentum. 4. Since momentum is a vector quantity we cannot add momenta (plural of momentum) like ordinary numbers; we must take account of direction. For the problems that we will consider this means that some momenta (usually in the original direction) will be considered to be positive (+) while other momenta (the opposite direction) will be negative ( ). 5. In problems it is essential to demonstrate that you know the conservation law. This should be stated as part of your working as: Total momentum before collision = total momentum after collision 3

7 Worked examples 1. Two cars are travelling towards each other as shown below. They collide, lock together and move forwards (i.e. to the right) after the collision. Find the speed of the cars immediately after the collision. Before After 10 m s 1 8 m s 1? 1200 kg A 1000 kg B 1200 kg 1000 kg Total momentum before collision = total momentum after collision Direction take motion as + m 1 u 1 = = 12,000 (m 1 + m 2 )v = ( )v m 2 u 2 = = = 2200v total momentum before = total momentum after = 2200v v = ie v = 1.8 m s 1 to the right 4

8 2. One vehicle (vehicle A) approaches another (vehicle B) from behind as shown below. The vehicles are moving with the speeds shown. After the collision the front vehicle is travelling at 11 ms 1. Calculate the speed of vehicle B after the collision. Before A B A After B 12 m s 1 9 m s 1 11 m s 1? 1200 kg 800 kg 1200 kg 800 kg Total momentum before collision = total momentum after collision Take motion as + m 1 u 1 = = m 1 v 1 = m 2 u 2 = = m 2 v 2 = 800 v 2 total momentum before = total momentum after = v = v 2 v 2 = v 2 = 10.5 ms 1 to the right Note: In momentum problems it can help to lay out your working under the headings before and after. Always draw a diagram of the situation before and after, including all relevant details such as masses, velocities and directions of motion. Include the statement of conservation of momentum. 5

9 Kinetic energy in collisions Momentum is always conserved in collisions and explosions. By the law of conservation of energy, the total energy is also conserved in collisions and explosions, but kinetic energy is not necessarily conserved. There are two kinds of collision: (a) those in which kinetic energy (E k ) is conserved i.e. total E k before = total E k after This is called an elastic collision. (b) those in which kinetic energy is not conserved i.e. E k is lost during the collision to other forms of energy, such as heat energy This is called an inelastic collision. If after a collision the objects stick together, this is always an inelastic collision. If the objects bounce apart the collision may be elastic; the only sure way of finding out is to calculate the total E k before and after the collision. Usually this will involve using conservation of momentum first to calculate all the relevant velocities. Remember, momentum is always conserved in the absence of external forces. Reminder: E k = 1 2 mv 2 6

10 A special case If two objects of the same mass collide elastically, they exchange velocities after the collision. For example, if a cue ball travelling at 2 ms 1 collides with a second snooker ball of the same mass (a head-on collision, with no spin involved), the second ball will move off at 2 ms 1 and the cue ball will stop. This effect can be seen in Newton s cradle. (You may want to look at some YouTube clips of giant Newton s cradles.) Explosions and Newton s third law Explosions Explosions are treated in the same way as collisions, in that total momentum is conserved. For example, in the case of a bullet being fired from a gun, the total momentum before firing is zero, since nothing is moving. After firing, the bullet has momentum in the forward direction. The gun must therefore have the same magnitude of momentum in the opposite direction so the two momenta cancel each other out, leaving the total momentum still equal to zero. For this reason the gun must have a recoil velocity after the explosion (i.e. the gun jumps backwards). 7

11 It should be obvious that in an explosion kinetic energy is not conserved. Think about this. If a bomb explodes leading to an overall gain in kinetic energy. What kind of energy did the bomb have before the explosion? Worked example A gun of mass 1 kg fires a bullet of mass 5 g at a speed of 100 ms 1. Calculate the recoil velocity of the gun. Before After 0 ms 1 1 kg kg? 100 ms 1 1 kg kg Total momentum before explosion = total momentum after explosion Take motion as + momentum = 0 m 1 v 1 + m 2 v 2 = 0 (1 v 1 ) + ( ) = 0 (1 v 1 ) = 0 v 1 = -0.5 ie v 1 = 0.5 ms 1 in the opposite direction to the bullet 8

12 Momentum and Newton s third law It can be shown that conservation of momentum and Newton s third law mean the same thing. Starting from conservation of momentum: total momentum before = total momentum after m 1 u 1 + m 2 u 2 = m 1 v 1 + m 2 v 2 Rearrange: m 2 u 2 m 2 v 2 = m 1 v 1 m 1 u 1 m 2 (u 2 v 2 ) = m 1 (v 1 u 1 ) or: m 2 (v 2 u 2 ) = m 1 (v 1 u 1 ) ie (change in momentum = (change in momentum of of object 2) object 1) In other words, in any particular example involving two objects colliding, if the momentum of one object increases by, for example, 6 kgms 1, then the momentum of the other object must decrease by 6 kgms 1. Consider again the previous example. We had concluded that: m 2 (v 2 u 2 ) = m 1 (v 1 u 1 ) Applying a = v-u as at = v-u t And as F = ma m 2 a 2 t = m 1 a 1 t F 2 t = F 1 t so F 2 = F 1 Newton s third law states that if one body exerts a force on a second body, the second body exerts a force on the first body that is equal in size and opposite in direction. Note: These forces operate on different bodies so they do not cancel each other out. 9

13 Impulse Obvious question: you re stranded by a fire on an upper floor and have to jump. Would you rather jump onto grass or concrete? Why? Does what you land on affect your speed of fall? What difference does a different material make when you land on it? Try to use precise physics terminology rather than everyday language. What is the physics behind this situation? Let s look at some numbers. A student jumps from a window ledge 2 m high. Find their velocity when they reach the ground. This will be the same whatever surface they land on. When the student lands, the different surfaces have a different amount of give. This means the time for the student s deceleration (negative acceleration) will be different. For this example we will take the time of landing on the concrete to be 0.01 s and on the grass to be 0.3 s, as the grass gives way underneath. (a) Estimate the average force exerted on the student by the concrete and grass. (b) Find the deceleration and therefore the average force: concrete grass What do you think about these results? If you had no choice but to jump onto concrete, what could you do to help minimise the chance of injury? In each of these examples, the change in momentum is the same since the speed at which the student hits the ground is the same. The difference is the time in which the change in momentum takes place. Rearranging Newton s second law helps to make this more explicit. 10

14 Momentum and Newton s second law Newton s second law: F = ma but a = v-u t F = m v-u t so F = m v-u = mv - mu t t which is the rate of change of momentum. This is how Newton himself defined his second law. The law can be rearranged: Ft = mv - mu The product Ft is called the impulse. Impulse is a vector quantity. The units of Ft could be kgms 1 since these are the units of momentum, but they are also Ns, and these are the units that should be used for impulse. 11

15 The force calculated from the impulse relationship is the average force. The force involved is rarely constant, eg consider a tennis ball hit by a racquet: The force exerted by the racquet on the ball will change with time. The impulse is calculated from the area under the graph, so: impulse = area under a force time graph This is the case regardless of the shape of the graph. Leading on from this, what else is represented by the area under a force time graph? 12

16 Worked examples 1. In a snooker game, the cue ball, of mass 0.2 kg, is accelerated from the r est to a velocity of 2 ms 1 by a force from the cue which lasts 50 ms. what size of force is exerted by the cue? u = 0, v = 2 m s 1, t = 50 ms = 0.05 s, m = 0.2 kg, F =? Ft = mv - mu F 0.05 = (0.2 2) (0.2 0) F 0.05 = 0.4 F = 8 N 2. A tennis ball of mass 100 g, initially at rest, is hit by a racquet. The racquet is in contact with the ball for 20 ms and the force of contact varies over this period, as shown in the graph. Determine the speed of the ball as it l eaves the racquet. impulse = area under graph = ½ = 4 Ns u = 0, m = 100 g = 0.1 kg, v =? Ft = mv - mu 4 = 0.1v (0.1 0) 4 = 0.1v v = 40 ms 1 13

17 3. A tennis ball of mass 0.1 kg travelling horizontally at 10 ms 1 is struck in the opposite direction by a tennis racket. The tennis ball rebounds horizontally at 15 ms 1 and is in contact with the racket for 50 ms. Calculate the force exerted on the ball by the racket. m = 0.1 kg, u = 10 m s 1, v = -15 m s 1 (opposite direction to u) t = 50 ms = 0.05 s Ft = mv - mu 0.05F = (0.1 ( 15)) (0.1 10) 0.05F = F = 2.5 F = 50 N (the negative sign indicates force in opposite direction to the initial velocity) 14

18 Problems Collisions and explosions 1. What is the momentum of the object in each of the following situations? (a) (b) (c) 2. A trolley of mass 2 0 kg is travelling with a speed of 1 5 m s 1. The trolley collides and sticks to a stationary trolley of mass 2 0 kg. (a) (b) Calculate the velocity of the trolleys immediately after the collision. Show that the collision is inelastic. 3. A target of mass 4 0 kg hangs from a tree by a long string. An arrow of mass 100 g is fired at the target and embeds itself in the target. The speed of the arrow is 100 m s 1 just before it strikes the target. What is the speed of the target immediately after the impact? 4. A trolley of mass 2 0 kg is moving at a constant speed when it collides and sticks to a second stationary trolley. The graph shows how the speed of the 2 0 kg trolley varies with time. v / ms time / s Determine the mass of the second trolley. 15

19 5. In a game of bowls a bowl of mass 1 0 kg is travelling at a speed of 2 0 ms 1 when it hits a stationary jack straight on. The jack has a mass of 300 g. The bowl continues to move straight on with a speed of 1 2 m s 1 after the collision. (a) (b) What is the speed of the jack immediately after the collision? How much kinetic energy is lost during the collision? 6. Two space vehicles make a docking manoeuvre (joining together) in space. One vehicle has a mass of 2000 kg and is travelling at 9 0 m s 1. The second vehicle has a mass of 1500 kg and is moving at 8 0 m s 1 in the same direction as the first. Determine their common velocity after docking. 7. Two cars are travelling along a race track. The car in front has a mass of 1400 kg and is moving at 20 m s 1. The car behind has a mass of 1000 kg and is moving at 30 m s 1. The cars collide and as a result of the collision the car in front has a speed of 25 m s 1. (a) (b) Determine the speed of the rear car after the collision. Show clearly whether this collision is elastic or inelastic. 8. One vehicle approaches another from behind as shown. The vehicle at the rear is moving faster than the one in front and they collide. This causes the vehicle in front to be nudged forward with an increased speed. Determine the speed of the rear vehicle immediately after the collision. 9. A trolley of mass 0 8 kg is travelling at a speed 1 5 m s 1. It collides head-on with another vehicle of mass 1 2 kg travelling at 2 0 m s 1 in the opposite direction. The vehicles lock together on impact. Determine the speed and direction of the vehicles after the collision. 16

20 10. A firework is launched vertically and when it reaches its maximum height it explodes into two pieces. One piece has a mass of 200 g and moves off with a speed of 10 m s 1. The other piece has a mass of 120 g. What is the velocity of the second piece of the firework? 11. Two trolleys initially at rest and in contact move apart when a plunger on one trolley is released. One trolley with a mass of 2 kg moves off with a speed of 4 m s 1. The other moves off with a speed of 2 ms 1, in the opposite direction. Calculate the mass of this trolley. 12. A man of mass 80 kg and woman of mass 50 kg are skating on ice. At one point they stand next to each other and the woman pushes the man. As a result of the push the man moves off at a speed of 0 5 m s 1. What is the velocity of the woman as a result of the push? 13. Two trolleys initially at rest and in contact fly apart when a plunger on one of them is released. One trolley has a mass of 2 0 kg and moves off at a speed of 2 0 m s 1. The second trolley has a mass of 3 0 kg. Calculate the velocity of this trolley. 14. A cue exerts an average force of 7 00 N on a stationary snooker ball of mass 200 g. The impact of the cue on the ball lasts for 45 0 ms. What is the speed of the ball as it leaves the cue? 15 A football of mass 500 g is stationary. When a girl kicks the ball her foot is in contact with the ball for a time of 50 ms. As a result of the kick the ball moves off at a speed of 10 m s 1. Calculate the average force exerted by her foot on the ball. 16. A stationary golf ball of mass 100 g is struck by a club. The ball moves off at a speed of 30 m s 1. The average force of the club on the ball is 100 N. Calculate the time of contact between the club and the ball. 17. The graph shows how the force exerted by a hockey stick on a stationary hockey ball varies with time. F/N time/ms ms 17

21 The mass of the ball is 150 g. Determine the speed of the ball as it leaves the stick. 18. A ball of mass 100 g falls from a height of 0 20 m onto concrete. The ball rebounds to a height of 0 18 m. The duration of the impact is 25 ms. Calculate: (a) (b) (c) (d) (e) the change in momentum of the ball caused by the bounce the impulse on the ball during the bounce the average unbalanced force exerted on the ball by the concrete the average unbalanced force of the concrete on the ball. What is the total average upwards force on the ball during impact? 19. A rubber ball of mass 40 0 g is dropped from a height of m onto the pavement. The ball rebounds to a height of m. The average force of contact between the pavement and the ball is 2 80 N. (a) (b) Calculate the velocity of the ball just before it hits the ground and the velocity just after hitting the ground. Calculate the time of contact between the ball and pavement. 20. A ball of mass 400 g travels falls from rest and hits the ground. The velocity-time graph represents the motion of the ball for the first 1 2 s after it starts to fall. 6 Speed / ms -1 0 A - 4 B C E D time / s (a) (b) (c) (d) Describe the motion of the ball during sections AB, BC, CD and DE on the graph. What is the time of contact of the ball with the ground? Calculate the average unbalanced force of the ground on the ball. How much energy is lost due to contact with the ground? 18

22 21. Water with a speed of 50 m s 1 is ejected horizontally from a fire hose at a rate of 25 kg s 1. The water hits a wall horizontally and does not rebound from the wall. Calculate the average force exerted on the wall by the water. 22. A rocket ejects gas at a rate of 50 kg s 1, ejecting it with a constant speed of 1800 m s 1. Calculate magnitude of the force exerted by the ejected gas on the rocket. 23. Describe in detail an experiment that you would do to determine the average force between a football boot and a football as the ball is being kicked. Draw a diagram of the apparatus and include all the measurements taken and details of the calculations carried out. 24. A 2 0 kg trolley travelling at 6 0 m s 1 collides with a stationary 1 0 kg trolley. The trolleys remain connected after the collision. (a) (b) Calculate: (i) the velocity of the trolleys just after the collision (ii) the momentum gained by the 1 0 kg trolley (iii) the momentum lost by the 2 0 kg trolley. The collision lasts for 0 50 s. Calculate the magnitude of the average force acting on each trolley. 25. In a problem two objects, having known masses and velocities, collide and stick together. Why does the problem ask for the velocity immediately after collision to be calculated? 26. A Newton s cradle apparatus is used to demonstrate conservation of momentum. Four steel spheres, each of mass 0.1 kg, are suspended so that they are in a straight line. Sphere 1 is pulled to the side and released, as shown in diagram I Diagram I Diagram II 19

23 When sphere 1 strikes sphere 2 (as shown by the dotted lines), sphere 4 moves off the line and reaches the position shown by the dotted lines. The student estimates that sphere 1 has a speed of 2 m s 1 when it strikes sphere 2. She also estimates that sphere 4 leaves the line with an initial speed of 2 m s 1. Hence conservation of momentum has been demonstrated. A second student suggests that when the demonstration is repeated there is a possibility that spheres 3 and 4, each with a speed of 0 5 m s 1, could move off the line as shown in diagram II. Use your knowledge of physics to show this is not possible. 20

24 Solutions Section 3: Collisions and explosions 1. (a) 20 kg m s 1 to the right (b) 500 kg m s 1 downwards (c) 9 kg m s 1 to the left 2. (a) 0 75 m s 1 in the direction in which the first trolley was moving m s kg 5. (a) 2 7 m s 1 (b) 0 19 J m s 1 in the original direction of travel 7. (a) 23 m s m s m s 1 in the original direction of travel of the 1 2 kg trolley m s 1 in the opposite direction to the first piece kg m s 1 in the opposite direction to the velocity of the man m s 1 in the opposite direction to the velocity of the first trolley m s N s m s 1 21

25 18 (a) kg m s 1 if you have chosen upwards directions to be positive; 0 39 kg m s 1 if you have chosen downwards directions to be positive (b) N s if you have chosen upwards directions to be positive (c) 15 6 N downwards (d) 15 6 N upwards (e) 16 6 N upwards 19. (a) v before = 3 96 m s 1 downwards; v after = 2 97 m s 1 upwards (b) s 20. (b) 0 2 s (c) 20 N upwards (or 20 N for the sign convention used in the graph) (d) 4 0 J N towards the wall N 24. (a) (i) 4 0 m s 1 in the direction the 2 0 kg trolley was travelling (ii) 4 0 kg m s 1 in the direction the 2 0 kg trolley was travelling (iii) 4 0 kg m s 1 in the direction the 2 0 kg trolley was travelling (b) 8 N 22

### Differentiated Physics Practice Questions

Differentiated Physics Practice Questions Multiple Choice Identify the choice that best completes the statement or answers the question. 1. A 100-kg cannon at rest contains a 10-kg cannon ball. When fired,

### Chapter 7: Momentum and Impulse

Chapter 7: Momentum and Impulse 1. When a baseball bat hits the ball, the impulse delivered to the ball is increased by A. follow through on the swing. B. rapidly stopping the bat after impact. C. letting

### Higher Physics Our Dynamic Universe Notes

Higher Physics Our Dynamic Universe Notes Teachers Booklet Previous knowledge This section builds on the knowledge from the following key areas from Dynamics and Space Booklet 1 - Dynamics Velocity and

### Assignment Work (Physics) Class :Xi Chapter :04: Motion In PLANE

1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. Assignment Work (Physics) Class :Xi Chapter :04: Motion In PLANE State law of parallelogram of vector addition and derive expression for resultant of two vectors

### Chapter 7 Momentum and Impulse

Chapter 7 Momentum and Impulse Collisions! How can we describe the change in velocities of colliding football players, or balls colliding with bats?! How does a strong force applied for a very short time

### Summary Notes. to avoid confusion it is better to write this formula in words. time

National 4/5 Physics Dynamics and Space Summary Notes The coloured boxes contain National 5 material. Section 1 Mechanics Average Speed Average speed is the distance travelled per unit time. distance (m)

### Physics 125 Practice Exam #3 Chapters 6-7 Professor Siegel

Physics 125 Practice Exam #3 Chapters 6-7 Professor Siegel Name: Lab Day: 1. A concrete block is pulled 7.0 m across a frictionless surface by means of a rope. The tension in the rope is 40 N; and the

### Elastic and Inelastic Collisions

Elastic and Inelastic Collisions Different kinds of collisions produce different results. Sometimes the objects stick together. Sometimes the objects bounce apart. What is the difference between these

### Momentum, Impulse and Momentum Change

Name: Momentum, Impulse and Momentum Change Read from Lesson 1 of the Momentum and Collisions chapter at The Physics Classroom: http://www.physicsclassroom.com/class/momentum/u4l1a.html http://www.physicsclassroom.com/class/momentum/u4l1b.html

### Kinetic Energy (A) stays the same stays the same (B) increases increases (C) stays the same increases (D) increases stays the same.

1. A cart full of water travels horizontally on a frictionless track with initial velocity v. As shown in the diagram, in the back wall of the cart there is a small opening near the bottom of the wall

### Physics in action: Impulse

Physics in action: Impulse A very important application of impulse is improving safety and reducing injuries. In many cases, an object needs to be brought to rest from a certain initial velocity. This

### Newton s Third Law, Momentum, Center of Mass

Team: Newton s Third Law, Momentum, Center of Mass Newton s Third Law is a deep statement on the symmetry of interaction between any two bodies in the universe. How is the pull of the earth on the moon

### PHYSICS 111 HOMEWORK SOLUTION #8. March 24, 2013

PHYSICS 111 HOMEWORK SOLUTION #8 March 24, 2013 0.1 A particle of mass m moves with momentum of magnitude p. a) Show that the kinetic energy of the particle is: K = p2 2m (Do this on paper. Your instructor

### Exam Three Momentum Concept Questions

Exam Three Momentum Concept Questions Isolated Systems 4. A car accelerates from rest. In doing so the absolute value of the car's momentum changes by a certain amount and that of the Earth changes by:

### Newton s Third Law. Newton s Third Law of Motion. Action-Reaction Pairs

Section 4 Newton s Third Law Reading Preview Key Concepts What is Newton s third law of motion? How can you determine the momentum of an object? What is the law of conservation of momentum? Key Terms momentum

### Chapter 4. Forces and Newton s Laws of Motion. continued

Chapter 4 Forces and Newton s Laws of Motion continued Clicker Question 4.3 A mass at rest on a ramp. How does the friction between the mass and the table know how much force will EXACTLY balance the gravity

### 2.2 NEWTON S LAWS OF MOTION

2.2 NEWTON S LAWS OF MOTION Sir Isaac Newton (1642-1727) made a systematic study of motion and extended the ideas of Galileo (1564-1642). He summed up Galileo s observation in his three laws of motion

### Physics Midterm Review. Multiple-Choice Questions

Physics Midterm Review Multiple-Choice Questions 1. A train moves at a constant velocity of 90 km/h. How far will it move in 0.25 h? A. 10 km B. 22.5 km C. 25 km D. 45 km E. 50 km 2. A bicyclist moves

### Mechanics 1. Revision Notes

Mechanics 1 Revision Notes July 2012 MECHANICS 1... 2 1. Mathematical Models in Mechanics... 2 Assumptions and approximations often used to simplify the mathematics involved:... 2 2. Vectors in Mechanics....

### Work, Energy & Momentum Homework Packet Worksheet 1: This is a lot of work!

Work, Energy & Momentum Homework Packet Worksheet 1: This is a lot of work! 1. A student holds her 1.5-kg psychology textbook out of a second floor classroom window until her arm is tired; then she releases

### PHYSICS MIDTERM REVIEW

1. The acceleration due to gravity on the surface of planet X is 19.6 m/s 2. If an object on the surface of this planet weighs 980. newtons, the mass of the object is 50.0 kg 490. N 100. kg 908 N 2. If

### Exampro GCSE Physics. P2 Momentum and Energy Calculations Self Study Higher tier. Name: Class: Author: Date: Time: 110. Marks: 110.

Exampro GCSE Physics P2 Momentum and Energy Calculations Self Study Higher tier Name: Class: Author: Date: Time: 0 Marks: 0 Comments: Page of 33 Q. The figure below shows a skateboarder jumping forwards

### Chapter Assessment Concept Mapping. Mastering Concepts

launch point with horizontal momentum. Where does the vertical momentum come from as the athlete vaults over the crossbar? The vertical momentum comes from the impulsive force of Earth against the pole.

### Unit 1 Our Dynamic Universe

North Berwick High School Higher Physics Department of Physics Unit 1 Our Dynamic Universe Section 1 Equations of Motion Section 1 Equations of Motion Note Making Make a dictionary with the meanings of

### AP physics C Web Review Ch 6 Momentum

Name: Class: _ Date: _ AP physics C Web Review Ch 6 Momentum Please do not write on my tests Multiple Choice Identify the choice that best completes the statement or answers the question. 1. The dimensional

### " # \$%! Text and page layout copyright Martin Cunningham, Majority of clipart copyright

" # \$% Text and page layout copyright Martin Cunningham, 25 Majority of clipart copyright wwwclipartcom, 25 1 1) SCALAR and VECTOR QUANTITIES The following are some of the quantities you will meet in the

### Mass, energy, power and time are scalar quantities which do not have direction.

Dynamics Worksheet Answers (a) Answers: A vector quantity has direction while a scalar quantity does not have direction. Answers: (D) Velocity, weight and friction are vector quantities. Note: weight and

### 1 of 6 10/17/2009 2:32 PM

1 of 6 10/17/2009 2:32 PM Chapter 9 Homework Due: 9:00am on Monday, October 19, 2009 Note: To understand how points are awarded, read your instructor's Grading Policy. [Return to Standard Assignment View]

### PRELAB: NEWTON S 3 RD LAW AND MOMENTUM CONSERVATION

Newton s 3rd Law and Momentum Conservation, p./ PRELAB: NEWTON S 3 RD LAW AND MOMENTUM CONSERVATION Read over the lab and then answer the following questions about the procedures:. Write down the definition

### QUESTIONS : CHAPTER-5: LAWS OF MOTION

QUESTIONS : CHAPTER-5: LAWS OF MOTION 1. What is Aristotle s fallacy? 2. State Aristotlean law of motion 3. Why uniformly moving body comes to rest? 4. What is uniform motion? 5. Who discovered Aristotlean

### Newton s Third Law, Momentum, Center of Mass

Team: Newton s Third Law, Momentum, Center of Mass Newton s Third Law is a deep statement on the symmetry of interaction between any two bodies in the universe. How is the pull of the earth on the moon

### LAB 4: MOMENTUM AND COLLISIONS

1 Name Date Day/Time of Lab Partner(s) Lab TA LAB 4: MOMENTUM AND COLLISIONS NEWTON S THIRD LAW OBJECTIVES To examine action-reaction force pairs To examine collisions and relate the law of conservation

### Newton s Laws of Motion

Section 3.2 Newton s Laws of Motion Objectives Analyze relationships between forces and motion Calculate the effects of forces on objects Identify force pairs between objects New Vocabulary Newton s first

### Center of Mass/Momentum

Center of Mass/Momentum 1. 2. An L-shaped piece, represented by the shaded area on the figure, is cut from a metal plate of uniform thickness. The point that corresponds to the center of mass of the L-shaped

### charge is detonated, causing the smaller glider with mass M, to move off to the right at 5 m/s. What is the

This test covers momentum, impulse, conservation of momentum, elastic collisions, inelastic collisions, perfectly inelastic collisions, 2-D collisions, and center-of-mass, with some problems requiring

### Chapter 9. particle is increased.

Chapter 9 9. Figure 9-36 shows a three particle system. What are (a) the x coordinate and (b) the y coordinate of the center of mass of the three particle system. (c) What happens to the center of mass

### Experiment 7 ~ Conservation of Linear Momentum

Experiment 7 ~ Conservation of Linear Momentum Purpose: The purpose of this experiment is to reproduce a simple experiment demonstrating the Conservation of Linear Momentum. Theory: The momentum p of an

### 1) 0.33 m/s 2. 2) 2 m/s 2. 3) 6 m/s 2. 4) 18 m/s 2 1) 120 J 2) 40 J 3) 30 J 4) 12 J. 1) unchanged. 2) halved. 3) doubled.

Base your answers to questions 1 through 5 on the diagram below which represents a 3.0-kilogram mass being moved at a constant speed by a force of 6.0 Newtons. 4. If the surface were frictionless, the

### 2.5 Newton s Third Law of Motion. SUMMARY Newton s Second Law of Motion. Section 2.4 Questions

SUMMARY Newton s Second Law of Motion Newton s second law of motion relates the acceleration of an object to the mass of the object and the net force acting on it. The equation is a = F net or F m net

### The Physics of Kicking a Soccer Ball

The Physics of Kicking a Soccer Ball Shael Brown Grade 8 Table of Contents Introduction...1 What actually happens when you kick a soccer ball?...2 Who kicks harder shorter or taller people?...4 How much

### PHYS 117- Exam I. Multiple Choice Identify the letter of the choice that best completes the statement or answers the question.

PHYS 117- Exam I Multiple Choice Identify the letter of the choice that best completes the statement or answers the question. 1. Car A travels from milepost 343 to milepost 349 in 5 minutes. Car B travels

### PHY231 Section 2, Form A March 22, 2012. 1. Which one of the following statements concerning kinetic energy is true?

1. Which one of the following statements concerning kinetic energy is true? A) Kinetic energy can be measured in watts. B) Kinetic energy is always equal to the potential energy. C) Kinetic energy is always

### Physics Exam Q1 Exam, Part A Samples

Physics Exam Q1 Exam, Part A Samples 1. An object starts from rest and accelerates uniformly down an incline. If the object reaches a speed of 40 meters per second in 5 seconds, its average speed is (A)

### STAAR Science Tutorial 25 TEK 8.6C: Newton s Laws

Name: Teacher: Pd. Date: STAAR Science Tutorial 25 TEK 8.6C: Newton s Laws TEK 8.6C: Investigate and describe applications of Newton's law of inertia, law of force and acceleration, and law of action-reaction

### Proof of the conservation of momentum and kinetic energy

Experiment 04 Proof of the conservation of momentum and kinetic energy By Christian Redeker 27.10.2007 Contents 1.) Hypothesis...3 2.) Diagram...7 3.) Method...7 3.1) Apparatus...7 3.2) Procedure...7 4.)

### Physical Science Chapter 2. Forces

Physical Science Chapter 2 Forces The Nature of Force By definition, a Force is a push or a pull. A Push Or A Pull Just like Velocity & Acceleration Forces have both magnitude and direction components

### 356 CHAPTER 12 Bob Daemmrich

Standard 7.3.17: Investigate that an unbalanced force, acting on an object, changes its speed or path of motion or both, and know that if the force always acts toward the same center as the object moves,

### Lab 8: Ballistic Pendulum

Lab 8: Ballistic Pendulum Equipment: Ballistic pendulum apparatus, 2 meter ruler, 30 cm ruler, blank paper, carbon paper, masking tape, scale. Caution In this experiment a steel ball is projected horizontally

### Vectors and Scalars Velocity and Acceleration

Vectors and Scalars Velocity and Acceleration Scalar Quantity Quantities that have only magnitude (size) but no direction are scalar quantities. Examples: mass, distance, time, energy and speed. Vector

### ACTIVITY 6: Falling Objects

UNIT FM Developing Ideas ACTIVITY 6: Falling Objects Purpose and Key Question You developed your ideas about how the motion of an object is related to the forces acting on it using objects that move horizontally.

### NEWTON S LAWS OF MOTION

Name Period Date NEWTON S LAWS OF MOTION If I am anything, which I highly doubt, I have made myself so by hard work. Isaac Newton Goals: 1. Students will use conceptual and mathematical models to predict

### Chapter 9. is gradually increased, does the center of mass shift toward or away from that particle or does it remain stationary.

Chapter 9 9.2 Figure 9-37 shows a three particle system with masses m 1 3.0 kg, m 2 4.0 kg, and m 3 8.0 kg. The scales are set by x s 2.0 m and y s 2.0 m. What are (a) the x coordinate and (b) the y coordinate

### AP Physics 1 Midterm Exam Review

AP Physics 1 Midterm Exam Review 1. The graph above shows the velocity v as a function of time t for an object moving in a straight line. Which of the following graphs shows the corresponding displacement

### 2.1 Force and Motion Kinematics looks at velocity and acceleration without reference to the cause of the acceleration.

2.1 Force and Motion Kinematics looks at velocity and acceleration without reference to the cause of the acceleration. Dynamics looks at the cause of acceleration: an unbalanced force. Isaac Newton was

### Honors Physics. Momentum Review

Honors Physics Moentu Review Nae Date. A freight car of ass 0,000 kg oves along a frictionless level railroad track with a constant speed of 5 /s. What is the oentu of the car A. 30,000 kg /s B. 3,000

### B) 40.8 m C) 19.6 m D) None of the other choices is correct. Answer: B

Practice Test 1 1) Abby throws a ball straight up and times it. She sees that the ball goes by the top of a flagpole after 0.60 s and reaches the level of the top of the pole after a total elapsed time

### Physics 101. Chapter 5: Newton s Third Law

Physics 101 Today Chapter 5: Newton s Third Law First, let s clarify notion of a force: Previously defined force as a push or pull. Better to think of force as an interaction between two objects. You can

### 9. The kinetic energy of the moving object is (1) 5 J (3) 15 J (2) 10 J (4) 50 J

1. If the kinetic energy of an object is 16 joules when its speed is 4.0 meters per second, then the mass of the objects is (1) 0.5 kg (3) 8.0 kg (2) 2.0 kg (4) 19.6 kg Base your answers to questions 9

### Explaining Motion:Forces

Explaining Motion:Forces Chapter Overview (Fall 2002) A. Newton s Laws of Motion B. Free Body Diagrams C. Analyzing the Forces and Resulting Motion D. Fundamental Forces E. Macroscopic Forces F. Application

### M OTION. Chapter2 OUTLINE GOALS

Chapter2 M OTION OUTLINE Describing Motion 2.1 Speed 2.2 Vectors 2.3 Acceleration 2.4 Distance, Time, and Acceleration Acceleration of Gravity 2.5 Free Fall 2.6 Air Resistence Force and Motion 2.7 First

Section Review Answers Chapter 12 Section 1 1. Answers may vary. Students should say in their own words that an object at rest remains at rest and an object in motion maintains its velocity unless it experiences

### ANSWER KEY. Reviewing Physics: The Physical Setting THIRD EDITION. Amsco School Publications, Inc. 315 Hudson Street / New York, N.Y.

NSWER KEY Reviewing Physics: The Physical Setting THIRD EDITION msco School Publications, Inc. 315 Hudson Street / New York, N.Y. 10013 N 7310 CD Manufactured in the United States of merica 1345678910

### Chapter 4 Newton s Laws: Explaining Motion

Chapter 4 Newton s s Laws: Explaining Motion Newton s Laws of Motion The concepts of force, mass, and weight play critical roles. A Brief History! Where do our ideas and theories about motion come from?!

### Free Fall: Observing and Analyzing the Free Fall Motion of a Bouncing Ping-Pong Ball and Calculating the Free Fall Acceleration (Teacher s Guide)

Free Fall: Observing and Analyzing the Free Fall Motion of a Bouncing Ping-Pong Ball and Calculating the Free Fall Acceleration (Teacher s Guide) 2012 WARD S Science v.11/12 OVERVIEW Students will measure

### Newton s Third Law, Momentum, Center of Mass

Team: Newton s Third Law, Momentum, Center of Mass Part I. Newton s Third Law Atomic Springs When you push against a wall, you feel a force in the opposite direction. The harder you push, the harder the

### Chapter 06 Multi-format Test

Name: Class: Date: Chapter 06 Multi-format Test Modified True/False Indicate whether the statement is true or false. If false, change the identified word or phrase to make the statement true. 1. The inertia

### v v ax v a x a v a v = = = Since F = ma, it follows that a = F/m. The mass of the arrow is unchanged, and ( )

Week 3 homework IMPORTANT NOTE ABOUT WEBASSIGN: In the WebAssign versions of these problems, various details have been changed, so that the answers will come out differently. The method to find the solution

### PHY231 Section 1, Form B March 22, 2012

1. A car enters a horizontal, curved roadbed of radius 50 m. The coefficient of static friction between the tires and the roadbed is 0.20. What is the maximum speed with which the car can safely negotiate

### STRAIGHT LINE MOTION. 1 Equations of Straight Line Motion (Constant Acceleration)

1 CHAPTER. STRAIGHT LINE MOTION (CONSTANT ACCELERATION) 1 INSTITIÚID TEICNEOLAÍOCHTA CHEATHARLACH INSTITUTE OF TECHNOLOGY CARLOW STRAIGHT LINE MOTION By definition, mechanics is the study of bodies at

### Review Vocabulary force: a push or a pull. Vocabulary Newton s third law of motion

Standard 7.3.17: Investigate that an unbalanced force, acting on an object, changes its speed or path of motion or both, and know that if the force always acts toward the same center as the object moves,

### 2 ONE- DIMENSIONAL MOTION

2 ONE- DIMENSIONAL MOTION Chapter 2 One-Dimensional Motion Objectives After studying this chapter you should be able to derive and use formulae involving constant acceleration; be able to understand the

### ACTIVITY 1: Gravitational Force and Acceleration

CHAPTER 3 ACTIVITY 1: Gravitational Force and Acceleration LEARNING TARGET: You will determine the relationship between mass, acceleration, and gravitational force. PURPOSE: So far in the course, you ve

### ACTIVITY SIX CONSERVATION OF MOMENTUM ELASTIC COLLISIONS

1 PURPOSE ACTIVITY SIX CONSERVATION OF MOMENTUM ELASTIC COLLISIONS For this experiment, the Motion Visualizer (MV) is used to capture the motion of two frictionless carts moving along a flat, horizontal

### Units DEMO spring scales masses

Dynamics the study of the causes and changes of motion Force Force Categories ContactField 4 fundamental Force Types 1 Gravity 2 Weak Nuclear Force 3 Electromagnetic 4 Strong Nuclear Force Units DEMO spring

Chapter 8 pages 869 870 1. The rotational velocity of a merry-goround is increased at a constant rate from 1.5 rad/s to 3.5 rad/s in a time of 9.5 s. What is the rotational acceleration of the merry-go-round?

### Described by Isaac Newton

Described by Isaac Newton States observed relationships between motion and forces 3 statements cover aspects of motion for single objects and for objects interacting with another object An object at rest

### Name per due date mail box

Name per due date mail box Rolling Momentum Lab (1 pt for complete header) Today in lab, we will be experimenting with momentum and measuring the actual force of impact due to momentum of several rolling

### NEWTON S LAWS OF MOTION

NEWTON S LAWS OF MOTION Background: Aristotle believed that the natural state of motion for objects on the earth was one of rest. In other words, objects needed a force to be kept in motion. Galileo studied

### Physics of Rocket Flight

Physics of Rocket Flight In order to understand the behaviour of rockets it is necessary to have a basic grounding in physics, in particular some of the principles of statics and dynamics. This section

### STUDY GUIDE UNIT 10-Newton s Third Law

Name ANSWERS STUDY GUIDE UNIT 10-Newton s Third Law Date Agenda HW Tues, Jan 5 Wed., Jan 6 Review Video Read Section 6.1-6.3 Fill in Reading Notes (p. 2) Worksheet - Action-Reaction Pairs (p. 3) Go over

### 7 Newton s Third Law of Motion Action and Reaction. For every force, there is an equal and opposite force.

For every force, there is an equal and opposite force. 7.1 Forces and Interactions A force is always part of a mutual action that involves another force. 7.1 Forces and Interactions In the simplest sense,

### Tennessee State University

Tennessee State University Dept. of Physics & Mathematics PHYS 2010 CF SU 2009 Name 30% Time is 2 hours. Cheating will give you an F-grade. Other instructions will be given in the Hall. MULTIPLE CHOICE.

### Physics 2A, Sec B00: Mechanics -- Winter 2011 Instructor: B. Grinstein Final Exam

Physics 2A, Sec B00: Mechanics -- Winter 2011 Instructor: B. Grinstein Final Exam INSTRUCTIONS: Use a pencil #2 to fill your scantron. Write your code number and bubble it in under "EXAM NUMBER;" an entry

### 2 Mechanics. Kinematics. Displacement and distance 2.1

2 Mechanics 2.1 Kinematics Assessment statements 2.1.1 Define displacement, velocity, speed and acceleration. 2.1.2 Explain the difference between instantaneous and average values of speed, velocity and

### Q1. (a) State the difference between vector and scalar quantities (1)

Q1. (a) State the difference between vector and scalar quantities....... (1) (b) State one example of a vector quantity (other than force) and one example of a scalar quantity. vector quantity... scalar

### Principles and Laws of Motion

2009 19 minutes Teacher Notes: Ian Walter DipAppChem; TTTC; GDipEdAdmin; MEdAdmin (part) Program Synopsis This program begins by looking at the different types of motion all around us. Forces that cause

### AP Physics C Fall Final Web Review

Name: Class: _ Date: _ AP Physics C Fall Final Web Review Multiple Choice Identify the choice that best completes the statement or answers the question. 1. On a position versus time graph, the slope of

### EDUH 1017 - SPORTS MECHANICS

4277(a) Semester 2, 2011 Page 1 of 9 THE UNIVERSITY OF SYDNEY EDUH 1017 - SPORTS MECHANICS NOVEMBER 2011 Time allowed: TWO Hours Total marks: 90 MARKS INSTRUCTIONS All questions are to be answered. Use

### Name Period Chapter 10 Study Guide

Name _ Period Chapter 10 Study Guide Modified True/False Indicate whether the statement is true or false. 1. Unbalanced forces do not change an object s motion. 2. Friction depends on the types of surfaces

### Chapter 4 Dynamics: Newton s Laws of Motion. Copyright 2009 Pearson Education, Inc.

Chapter 4 Dynamics: Newton s Laws of Motion Force Units of Chapter 4 Newton s First Law of Motion Mass Newton s Second Law of Motion Newton s Third Law of Motion Weight the Force of Gravity; and the Normal

### MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question.

MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question. 1) Vector A has length 4 units and directed to the north. Vector B has length 9 units and is directed

### momentum (mass)(velocity) or p mv change in momentum change in [(mass)(velocity)] or p (mv)

5 Momentum 5-1 Impulse and Momentum Vocabulary Momentum: A measure of how difficult it is to stop a moving object. momentum (mass)(velocity) or p mv If the momentum of an object is changing, as it is when

### Physics Notes Class 11 CHAPTER 5 LAWS OF MOTION

1 P a g e Inertia Physics Notes Class 11 CHAPTER 5 LAWS OF MOTION The property of an object by virtue of which it cannot change its state of rest or of uniform motion along a straight line its own, is

### LAWS OF FORCE AND MOTION

reflect Does anything happen without a cause? Many people would say yes, because that often seems to be our experience. A cup near the edge of a table suddenly crashes to the fl oor. An apple falls from

### PS-5.1 Explain the relationship among distance, time, direction, and the velocity of an object.

PS-5.1 Explain the relationship among distance, time, direction, and the velocity of an object. It is essential for students to Understand Distance and Displacement: Distance is a measure of how far an

### Physics 11 Chapter 4 HW Solutions

Physics 11 Chapter 4 HW Solutions Chapter 4 Conceptual Question: 5, 8, 10, 18 Problems: 3, 3, 35, 48, 50, 54, 61, 65, 66, 68 Q4.5. Reason: No. If you know all of the forces than you know the direction

### 4 Gravity: A Force of Attraction

CHAPTER 1 SECTION Matter in Motion 4 Gravity: A Force of Attraction BEFORE YOU READ After you read this section, you should be able to answer these questions: What is gravity? How are weight and mass different?

### Instructor Now pick your pencils up and get this important equation in your notes.

Physics 605 Mechanical Energy (Read objectives on screen.) No, I haven t been playing with this toy the whole time you ve been gone, but it is kind of hypnotizing, isn t it? So where were we? Oh yes, we