8. Momentum of a body is:
(a) mv
(b) m + v
(c) m – v
(d) v – m
Ans: (a) mv
9. Action and reaction forces:
(a) Act on same body
(b) Cancel each other
(c) Act on different bodies
(d) None
Ans: (c) Act on different bodies
10. A stone falls due to:
(a) Inertia
(b) Force
(c) Gravity
(d) Mass
Ans: (c) Gravity
11. F = ma is which law?
(a) First
(b) Second
(c) Third
(d) Law of gravity
Ans: (b) Second
12. A heavier object has ______ acceleration for same force.
(a) More
(b) Less
Ans: (b) Less
13. Friction always acts:
(a) Along motion
(b) Against motion
Ans: (b) Against motion
14. Third law forces are:
(a) Unequal
(b) Equal
Ans: (b) Equal
15. What is needed to change state of rest or motion?
(a) Balanced force
(b) Unbalanced force
Ans: (b) Unbalanced force
True or False
1. Force can change shape of objects.
Ans: True
2. Inertia is the tendency to move faster.
Ans: False
3. A moving object doesn’t stop without force.
Ans: True
4. Mass and weight are the same.
Ans: False
5. More mass means more inertia.
Ans: True
6. A ball will roll forever on a rough floor.
Ans: False
7. Newton gave the laws of motion.
Ans: True
8. Friction helps in stopping a moving object.
Ans: True
9. Action and reaction act on same object.
Ans: False
10. Force always causes acceleration.
Ans: False (Only unbalanced force causes acceleration)
11. Balanced forces do not change motion.
Ans: True
12. Safety belts reduce injuries using inertia principle.
Ans: True
13. Momentum depends only on speed.
Ans: False
14. Third law forces act at different times.
Ans: False
15. A feather and a coin fall at same speed in vacuum.
Ans: True
