Describe the relationship between gravitational force and distance as shown in the diagram.

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1 Name Period Chapter 2 The Laws of Motion Review Describe the relationship between gravitational force and distance as shown in the diagram. Assess the information about gravity, mass, and weight. Read each statement. If it is true, write T in the center column. If it is false, write F in the center column and replace the underlined words to make the statement true. Statement Mass is a gravitational force exerted by an object. An object s weight is proportional to its mass. Mass is measured in newtons. If an object has twice the size of another object, it has half the weight. An object s mass decreases the farther it gets from Earth s surface. Corrected Statement FALSE: Weight is the gravitational force TRUE FALSE: Mass is measured in kg FALSE: Mass and Twice the weight FALSE: Weight Summarize Newton s first law of motion. If the net force on an object is zero, an object at rest Will Stay at Rest, an object at motion Will Stay in Motion. Explain the effect of inertia on objects at rest and objects in motion. Inertia is the tendency of an object to resist change. Latin for LAZY Summarize how friction and inertia act on an object sliding on a flat surface. Inertia causes a moving bject to keep moving, while friction will slow an objects motion

2 Identify 2 characteristics of motion that can be changed by forces. 1. SPEED 2. DIRECTION Draw the described forces. Use labeled arrows to indicate the forces on a box, and show the net forces in the column to the right. Description 1. A force of 200 N to the left and another force of 50 N to the left Net force 250 N to the LEFT 2. A force of 100 N to the right and a force of 80 N to the left 20 N to the RIGHT 3. A force of 180 N to the right and a force of 180 N to the left 0 N Identify the forces in the table above as balanced forces or unbalanced forces. 1. Unbalanced 2. Unbalanced 3. Balanced Summarize Newton s first law of motion If the net force on an object is zero, an object at rest, an object at motion. Explain the effect of inertia on objects at rest and objects in motion.

3 Summarize how friction and inertia act on an object sliding on a flat surface. Cite the effect of forces on an object at rest. Force Balanced Unbalanced Effect Object remains at Rest Object is set in Motion Describe the effect of forces on an object in motion. Force Effect In the direction of the object s motion Object will speed up or maintain constant speed In the direction other than that of the object s motion Object slows down or changes direction Recall the difference between velocity and acceleration. Velocity Speed & Direction Acceleration A change in Velocity Summarize Newton s second law of motion The ACCELERATION of an object is equal to the NET FORCE exerted on the object divided by an object s mass. Explain the equation for Newton s second law. a stands for a = F/m F stands for acceleration Force m/s 2 m stands for N mass kg Predict the corresponding result for each force.

4 Force An airplane s jet engine pushes air toward the back of the plane. A fisherman tosses an anchor away from his boat. Result Air pushes back, plane moves forward. Anchor applies force on the fisherman and his boat, pushing them in the opposite direction A skier digs ski poles into the snowy ground and pushes down and backward. Ground pushes back and moves the skier forward Summarize Newton s third law of motion in your own words. When one object applies a force on another object, the second object applies the same, but opposite force back. Define the 2 parts of a force pair 1. ACTION 2. REACTION Analyze why force pairs do not cancel each other. Equal and opposite forces Net Force Classify forces in the sentences below. Underline action forces; circle reaction forces. A swimmer pushes his arms back against the water in a pool, and the water pushes forward against his arms. A rocket engine pushes hot gas out in a downward direction, and the hot gas pushes upward on the engine. A trampoline hurls a girl into the air.

5 Model Newton s third law of motion in a drawing. Label these terms: action force force force pair Define momentum. The measure of how hard it is to stop a moving object Momentum: Circle the object that would be more difficult to stop. A 10-kg shopping cart moving at 5 m/s or 2-kg ball moving at 28 m/s If you have ever been in a car at a stoplight beside a large truck, you probably noticed that the car took off from the stop much more quickly than the truck. Explain why it is harder to start and stop the motion of a large truck than that of a small car. The truck has a greater mass than the car, so it requires more force to set it in motion. When it is in motion, its greater mass causes it to have more momentum, making in harder to stop.