1. What is the main difference between vector and scalar quantities? 4. What must be included with magnitude to represent a vector quantity?

Transcription

1 What is the main difference between vector and scalar quantities? 2. Give an example of a vector quantity. 3. Give an example of a scalar quantity. 4. What must be included with magnitude to represent a vector quantity? 5. Mass and force are not both vector quantities? Why? 6. In PHS the distance between each floor is 3.0 m. The elevator completes the following trips: Basement to 2nd floor 2nd floor to 1st floor 1st floor to 3rd floor 7. Calculate the total distance traveled and the displacement of the elevator A student leaving school walks 2.5 km north and then walks 1.0 km south. What is the studentʼs displacement? 2. A race car travels at an average speed of 80 m/s in a race. The total distance of the race is 640,000 m. How long does it take the race car to finish the race? 3. Which quantity will always change when an object accelerates? 4. How long will it take a car to accelerate from 20 m/s to 26 m/s at a rate of 1.4 m/s 2? 5. A sailboat travels 35 km in 5 hours. Describe the motion of the sailboat. 6. A bicycle rider is traveling at 7 m/s. During an 8 s period, the bicycle rider then slows down with a constant acceleration to a speed of 3 m/s. How far does the bicycle rider travel during the 8 s? 7. Four cars are timed going from 0 to 60 km/h. What quantity can be compared in the four cars? 8. A car has an oil drip. As the car moves, it drips oil at a regular rate, leaving a trail of spots on the road. Draw a diagram of the carʼs trail of spots if the car continuously slows down.

2 1.3 During which time intervals is the speed of the object decreasing?

3 Describe an event that this graph could be representing. What can you conclude about the motion of the car? 7. On the surface of the Moon, a ball is thrown straight up with an initial velocity. The ball has a constant acceleration due to the Moonʼs gravity. On a graph of the ballʼs velocity versus time, what would represent the ball at its highest point above the Moonʼs surface?

4 Two students are standing next to each other on a level field. One of the students throws a table tennis ball forward toward a line 2.0 m away. At the same time, the second student throws a bowling ball in the same direction. Both balls take the same time to travel the 2.0 m. Explain why only the second student feels a noticeable backward push when she throws her ball. 2. A student is driving her car when an insect strikes her windshield. Describe the action/reaction forces in this situation. 3. Two students are in-line skating. Student S has a mass of 60 kg and is pushing Student T, who has a mass of 40 kg. Student S is pushing Student T in a straight line with a force equal to the friction on Student Tʼs skates. What must happen if Student S continues to push Student T with the same force? 4. A toy cart that has a weight of 10 N moves with a constant velocity of 2 m/s to the right on a horizontal table. According to Newtonʼs laws of motion, what force does the table exert upward on the toy cart? 5. A ball has a mass of 0.1 kg and an initial velocity of 20m/s. The ball is given an acceleration of 30 m/s 2 for 5 s. What is the net force on the ball during acceleration? 6. A cart with a mass of 5 kg rests on a floor next to a wall. A person pushes on the cart to the left toward the wall with a force of 100 N. With what force does the wall push on the cart and in what direction? 7. A 1500 kg car has an applied forward force of 5000 N and experiences an air resistance of 1250 N. What is the carʼs acceleration? 8. A hockey player swings her hockey stick and strikes a puck. According to Newtonʼs third law of motion, what is a reaction to the stick pushing on the puck? 9. A performer pulls a tablecloth out from under a complete set of dinnerware. Explain why the dinnerware remains on the table. 10. What would happen to a parked car if it were to suddenly experience an unbalanced force? 11. What is the mass of an object weighing 63 N on Earth? 12. What term describes the tendency of a stationary object to resist being put into motion?

5 A person with a weight of 120 lb. is standing on a scale. What force is the scale exerting on the person? 2. Four students push on a block of wood with the forces shown in the diagram below. Assume friction is negligible. The block slides horizontally. What is the net force acting on the block of wood? 3. A 2000 kg car is pulling a 1000 kg trailer. The carʼs engine exerts a 6000 N force to move the car and the trailer. In addition, the car and the trailer each experience a 1000 N frictional force as they are being pulled, as represented below. What is the magnitude of the net force on this system? 4. A rock weighing 76 N experiences an upward force of 106 N. What is the net force acting on the rock? 5. The forces acting on a skateboarder moving at a constant velocity along a sidewalk are shown in the figure below. What is the net force on the skateboarder? 6. Draw a free body diagram of a box weighing 70 N experiencing an upward force if 150 N.

6 A student pushes a book across a classroom table. Explain the difference between the amount of force needed to start the book moving and the amount of force needed to keep it moving. 2. Explain why it is usually easier to keep a sliding object moving than it is to start the object moving. 3. A heavy box is at rest on an inclined plane. The box begins to slide down the inclined plane when a small force is applied to the box. The force is removed as soon as the box begins to slide. The speed of the box increases as the box slides down the inclined plane. In terms of friction, describe the cause of this increasing speed. 4. A car is parked on the side of a hill. In terms of friction, describe why the car does not move down the hill Describe the direction of the gravitational attraction between 2 masses. 2. What happens to the force between two objects as the distance between them increases? 3. The distance of the star Vega from Earth is 1.6 million times greater than the distance of the Sun from Earth. Compare the gravitational influence of Vega on Earth with the gravitational influence of the Sun on Earth. 4. One 7.0 kg bowling ball is lifted to a storage shelf 1.0 m above the floor. A second 7.0 kg ball is lifted to a storage shelf 2.0 m above the floor. Explain why the measured force of gravity on each ball is nearly identical. 5. Spaceship 1 is launched from the surface of the Earth toward the moon. Spaceship 2 is launched from a space station orbiting Earth toward the moon. Why does it take less force to launch Spaceship 2? 6. When a comet comes close to the Sun, the Sunʼs gravitational attraction causes the cometʼs path to curve. Why does the Sun not appear to move due to the cometʼs gravitational attraction?

7 Describe one result of the Earthʼs gravitational pull on the moon. What might cause the ball to fly off in a straight-line path? 4. The diagram below shows the path of a ball as it is spun in a circle before its release. Which arrow shows the direction of the centripetal force on the ball before the ball is released?

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