1. Newton’s Laws of Motion
1. Inertia
2. Fnet = ma
3. Action - Reaction
Practice Questions

2. Definition of Inertia
An object will continue in its state of motion until acted on by an outside force.

3. Examples of Inertia: Back to Forces
A ball rolls across the floor until it hits another object.
It is difficult to start pushing a stalled car.
Driving around a curve makes passengers feel like they are flying out of the car.
Back to Forces

4. Fnet = ma The net force on a mass causes it to accelerate.
* “net” means total

5. Back to Forces Free-Body Diagram:
Label all of the forces acting on the body.
Force of Gravity (Fg)
Normal Force (FN)
Fnet is the combination of the two forces.
Fnet = FN - Fg
Back to Forces

6. For every force, there is an equal and opposite force.
Action - Reaction
For every force, there is an equal and opposite force.
AKA: Forces come is pairs

7. Back to Forces A hammer hits a nail…and the nail hits the hammer too.
A golfer swings at a golfball, and the ball also hits the club.
If you touch something…it touches you back!!!
Back to Forces

8. Here are some practice questions:
Inertia
Fnet = ma 1 2 3 1 2 3
Action - Reaction 1 2 3

9. An object requires no force to keep moving through space.
Inertia
An object requires no force to keep moving through space.
False
True

10. A more massive object has more inertia as well.
False
True

11. Inertia
Referencing the diagram below, it is possible to break the lower string by pulling slowly.
False
True
Mass
Pull

12. How much force is required to accelerate a 4 kg mass at 3 m/s2?
Fnet = ma
How much force is required to accelerate a 4 kg mass at 3 m/s2?
a) 7 N
b) 1 N
c) 12 N
d) 16 N

13. Fnet = ma
As the mass increases while the force remains constant, the acceleration will also increase.
False
True

14. Fnet = ma c) 1/6 kg a) 25 kg b) 35 kg d) 6 kg
A force of 30 N creates an acceleration of 5 m/s2. What must the mass of the object be?
a) 25 kg
b) 35 kg
c) 1/6 kg
d) 6 kg

15. A person standing on the ground has only one force on them.
Action - Reaction
A person standing on the ground has only one force on them.
False
True

16. Action - Reaction False True
When a truck smashes into a bicycle, the bicycle experiences a larger force.
False
True

17. Action - Reaction False True
If an astronaut is floating in space and wishes to travel toward his space ship by shooting a gun, he should shoot the gun in the direction of the spaceship.
False
True

18. Back to Practice Questions
Way to Go!!!
That's Right!!!
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19. Back to Practice Questions
Oops!!!
Try again.
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20. Quit
Back to Forces