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Study guide for Newton’s Laws and Friction
Name: _____________________
1. Friction is a force that opposes an object’s motion. It exists in any two objects that are touching.
2. Describe rolling friction and give an example.
Rolling friction usually requires less force than the others, especially sliding and fluid friction. An
example can include anything with wheels.
3. Describe fluid friction and give an example.
Fluid friction is when any object is moving through a gas or a liquid. Examples include
swimming, sky diving, skateboarding.
4. How does inertia affect cars going downhill?
Since going downhill increases velocity, the car will be harder to stop. Mass does not affect the
velocity but it does affect how easy or hard it is to stop the car.
5. How does friction affect cars going downhill?
Cars with less friction tend to travel faster.
6. Name one way to increase friction
Make the surface rougher or increase force
7. How does mass affect the momentum of an object?
The more mass, the more momentum
8. Based on Newton’s first law of motion what happens to an object at rest if there is no
unbalanced force acting on it?
It doesn’t move. It still has a net force of zero.
9. Based on Newton’s first law of motion what happens to an object at motion if there is no
unbalanced force acting on it?
It keeps moving because there is no unbalanced force stopping it.
10. Explain Newton’s third law. Give an example.
For every action, there is an equal and opposite reaction. Planes move forward because of the
exhaust of their engines results in a reaction force which makes the plane accelerate.
11. Explain action and reaction forces. Give an example.
An action force is the original force that is being exerted. The reaction force is the other force
that responds in equal size but in an opposite direction. When a swimmer pushes his or her
hands through the water (action force), the water (the reaction force) is pushed in the opposite
direction. The same is true for the swimmer kicking the water: one leg pushes down and the
water pushes up, while the other leg pushes up and the water pushes down propelling the
swimmer forward.
12. What affects the amount of air resistance on an object?
The size and shape of the object determines the amount air resistance (fluid friction)
13. Newton’s second law says f = m x a.
Explain what happens to acceleration if mass increases but force remains the same?
Acceleration decreases
Explain what happens to acceleration if mass decreases but force remains the same?
Acceleration increases
Explain what happens to acceleration if force increases but mass remains the same?
Acceleration increases
Explain what happens to acceleration if force decreases but mass remains the same?
Acceleration decreases
14. How does force affect the direction of an object?
An object moves in the direction of the force.
15. What is the action and reaction forces in the following situations:
A swimmer
Reaction forces – body pushing forward through water, water pushing on the hands and
feet
Action forces – Hands pushing down and pushing water back
A skydiver
Reaction forces – air resistance (fluid friction)
Action forces – gravity pulling skydiver down, gravity pulling Earth to skydiver
(remember it is slight but it still happens!)
16. When do action and reaction force pairs occur?
Whether or not there is motion, these pairs occur.
17. Explain why friction occurs.
Friction occurs because the hills and valleys of two touching surfaces “stick to each other”
18. What are the two ways you can increase friction.
Friction can be increased by making surfaces rougher or by increasing the force pushing the
surfaces together
19. Name two ways friction can be harmful AND two ways it can be helpful.
There are several answers but here are a few:
Harmful: It is harmful when your tire tread wears down or holes in your jeans.
Helpful: Friction allows wheels to grip the road and helps you scrub pots.
20. How is inertia related to Newton’s first law of motion?
Newton’s first law says that matter resists any change in motion. Inertia is the tendency of
objects to resist changes In motion. Newton’s first law is also known as the law of inertia.
21. Name three action and reaction force pairs involved in doing your homework. Remember to
name what objects is exerting and what object is receiving the forces.
Action: Hand pushing on pencil Reaction: pencil pushing back on hand and pencil pushing on
paper
Action: Pencil pushing on paper; reaction: paper pushing on pencil, paper pushing onto desk
Action: Pushing down on chair and floor; reaction: chair and floor pushing back
22. Which has more momentum a roach scurrying 3 m/s down the hall or a cat running 5 m/s up the
hall? Explain.
The cat because it has more mass and velocity.
23. Why does friction occur?
Whenever two surfaces touch the microscopic hills and valley of the items “stick”.
24.