Question

a) inertia b) speed c) friction d) acceleration

1. which has more momentum: 1000 kg car moving 30 m/s or a 500 kg car moving 30 m/s?

a) both the same b) 500 kg car c) 1000 kg car d) neither

1. friction always works in the __________ direction as motion.

a) same b) opposite c) faster d) slower

1. when two equal forces act in opposite directions, the net force is: a) zero b) positive c) negative d) balanced

part b - true/false (10 questions)

1. newtons first law says objects keep doing what theyre doing unless acted on by a force.
2. velocity and speed mean exactly the same thing.
3. friction can produce heat.
4. acceleration means only speeding up.
5. a rocket launching is an example of newtons third law.
6. a net force of zero means the objects motion does not change.
7. the formula for momentum is mass × velocity.
8. inertia depends on mass.
9. pushing harder on a shopping cart makes it accelerate more.
10. forces always act alone, never in pairs.

part c - fill in the blank (10 questions)

1. newtons __________ law is also called the law of inertia.
2. the formula for speed is __________ ÷ time.
3. the unit of force is the __________.
4. acceleration is the change in __________ over time.
5. when forces are balanced, the net force is __________.
6. the force that slows objects down when they touch is called __________.
7. __________ is a measure of how hard it is to stop a moving object.
8. velocity includes both speed and __________.
9. according to newtons __________ law, for every action there is an equal and opposite reaction.
10. __________ is the rate at which velocity changes.

part d - matching (5 questions)

1. ____ inertia

a) the resistance to a change in motion

1. ____ net force

b) push or pull when all forces are combined

1. ____ acceleration

c) change in velocity over time

1. ____ momentum

d) product of mass and velocity

1. ____ friction

e) a force that opposes motion between surfaces

Explanation:

1. The momentum formula is $p = mv$. For the 1000 - kg car with $v = 30$ m/s, $p_1=1000\times30 = 30000$ kg·m/s. For the 500 - kg car with $v = 30$ m/s, $p_2 = 500\times30=15000$ kg·m/s. So the 1000 - kg car has more momentum.
2. Friction opposes motion, so it acts in the opposite direction of motion.
3. When two equal forces act in opposite directions, they cancel each other out and the net force is zero.
4. Newton's First Law states that an object at rest stays at rest and an object in motion stays in motion with the same speed and in the same direction unless acted upon by an unbalanced force.
5. Velocity is a vector (has magnitude and direction) while speed is a scalar (only magnitude).
6. Friction can convert kinetic energy into heat.
7. Acceleration is a change in velocity (speeding up, slowing down, or changing direction).
8. A rocket launching is an example of Newton's Third Law (action - reaction).
9. When the net force is zero, the object's motion does not change according to Newton's First Law.
10. The formula for momentum is $p=mv$.
11. Inertia is related to mass; more mass means more inertia.
12. According to Newton's Second Law $F = ma$, a greater force on an object of constant mass will cause greater acceleration.
13. Forces always occur in pairs according to Newton's Third Law.
14. Newton's First Law is the law of inertia.
15. The formula for speed is $s=\frac{d}{t}$ (distance divided by time).
16. The unit of force is the Newton.
17. Acceleration is the change in velocity over time.
18. When forces are balanced, the net force is zero.
19. Friction slows objects down when they touch.
20. Inertia is a measure of how hard it is to stop a moving object.
21. Velocity includes both speed and direction.
22. According to Newton's Third Law, for every action there is an equal and opposite reaction.
23. Acceleration is the rate at which velocity changes.
24. Inertia is the resistance to a change in motion.
25. Net force is the push or pull when all forces are combined.
26. Acceleration is the change in velocity over time.
27. Momentum is the product of mass and velocity.
28. Friction is a force that opposes motion between surfaces.

Answer:

1. c) 1000 kg car
2. b) Opposite
3. a) Zero
4. T
5. F
6. T
7. F
8. T
9. T
10. T
11. T
12. T
13. F
14. First
15. $\frac{d}{t}$
16. Newton
17. velocity
18. zero
19. Friction
20. Inertia
21. direction
22. Third
23. Acceleration
24. a)
25. b)
26. c)
27. d)
28. e)