# Chapter 12: Forces Study Guide

NAME ______DATE ______

Chapter 12: Forces – Study Guide

- Which statement illustrates Newton’s first law?
- A stone will not move unless something pushes or pulls it.
- A ball rolling across the floor eventually slows down.
- As a car comes to a stop, the passengers continue to move forward.
- All of the above

- Which object has the greatest inertia?
- a tennis ball c. a beach ball
- a bowling ball d. a volleyball

- What force causes a skater sliding on the ice to gradually slow down? ______

- If an equal force is applied to two cars of equal mass, Car A and Car B, Car A will have ______acceleration as (than) Car B.

- According to Newton’s Second Law, force is a product of ______and ______

- When you kick a stone, your foot exerts a force on the stone, and the stone exerts a force ______in size and ______in direction on your foot.

- An object’s momentum is determined by the object’s ______and ______

- If you divide momentum by velocity, the result is the value of the object’s ______

- If ______and ______increase, then momentum will also increase.

- List the unit, formula needed to solve, and variable used to represent each

Variable / Formula / Unit

Force

Mass

Acceleration

Momentum

Velocity

Mass

- Explain the action and reaction forces happening in this picture (check your notes!).

______

For each picture, identify which of Newton’s Laws is being demonstrated, and then explain the law.

- A pitcher in a professional baseball game throws a fastball, giving the baseball a momentum of 5.83 kg • m/s. Given that the baseball has a mass of 0.145 kg, what is its speed?

- In 1996, Michael Johnson ran 200.0 m in 19.32 s. Johnson’s mass at the time of his record-breaking run was about 77 kg. What was his momentum at his average speed?

- Although it cannot sustain its top speed for more than 8.65 s, the cheetah can run a distance of 274 m during that time. If a cheetah with a mass of 50.0 kg is moving at top speed, what is its momentum?

- The tendency of an object at rest to remain at rest is

- inertia. b. momentum.c. free fall. d. acceleration

- If the car you are riding in comes to a sudden stop, ______helps stop your forward motion.

- The property of matter that resists changes in motion is called ______.

- Why don’t action-reaction forces cancel each other out?

- The combination of all forces acting on an object is the ______.

- When the net force on an object is greater than ______, the object will accelerate in the direction of the greater force.

- Net force is ______

- A game of tug-of-war is an example of

a.rolling friction.c. streamlining.

b.air resistance.d. unbalanced forces.

- A book is sitting still on your desk. Are the forces acting on the book balanced or unbalanced?

Identify which of Newton’s three laws of motion specifically applies in each of the following situations:

- _____ Two bumper cars collide into each other and each car jolts backwards
- _____ When you give your friend a lift on your bike you have to pedal harder and faster to keep the

same speed (and acceleration) as you had before when you were on your bike alone.

- _____ Force = Mass x Acceleration
- _____ For every action there is an equal and opposite reaction.
- _____ When you are standing in a subway train, and the train suddenly stops, your body continues to go

forward.

- _____ An object at rest/motion will stay at rest/motion unless acted on by an outside, unbalanced

force.

- _____ A boy is going down a slide. As he reaches the bottom, friction causes him to slow down and

stop.

- _____ As the wheels of a drag racing car smoke and spin backwards, they eventually begin to grip the

race track and push backwards on the road. In turn, the road reacts by pushing the wheels

forward.

- _____ When you throw a bowling ball out of a canoe, the bowling ball moves forward and the canoe

moves backward.

- _____ A little girl who has been pulling a sled behind her in the snow is crying because when she

stopped to tie her shoe, the sled kept moving and hit her in the back of the leg.

- The value for the acceleration of objects in free fall near Earth is ______

- Free fall is the motion of an object resulting from ______.

- Define each type of friction:
- Kinetic

- Static

- Rolling

- Sliding

- The friction between the bristles of your toothbrush and the surfaces of your teeth is an example of

a.rolling friction.c. helpful friction.

b.static friction.d. All of the above

- The friction between a book at rest and the desk it is lying on is an example of ______friction.