31. A body moving in a straight line with constant speed has:
A) No force acting
B) Constant force
C) Decreasing force
D) Increasing force
32. The force that keeps planets in orbit around the Sun is:
A) Friction
B) Gravity
C) Tension
D) Normal force
33. When a car stops suddenly, passengers move forward due to:
A) Acceleration
B) Inertia
C) Friction
D) Gravity
34. If an object is moving in a circle, its velocity is:
A) Constant
B) Changing direction
C) Zero
D) Infinite
35. The third law of motion states:
A) F = ma
B) For every action, there is an equal and opposite reaction
C) Energy is conserved
D) Momentum remains constant
36. A 10 kg object is moving with an acceleration of 5 m/s². What is the net force acting on it?
a) 5 N
b) 10 N
c) 50 N
d) 500 N
37. A car of mass 1000 kg accelerates from 10 m/s to 20 m/s in 5 seconds. What is the force applied?
a) 2000 N
b) 1000 N
c) 5000 N
d) 3000 N
38. A 2 kg block is sliding on a frictionless surface with a velocity of 4 m/s. What is its momentum?
a) 4 kg·m/s
b) 6 kg·m/s
c) 8 kg·m/s
d) 10 kg·m/s
39. A force of 15 N is applied to a 3 kg object. What is its acceleration?
a) 2 m/s²
b) 3 m/s²
c) 5 m/s²
d) 10 m/s²
40. A ball of mass 0.5 kg is dropped from a height. What will be its velocity just before hitting the ground (ignore air resistance, g = 9.8 m/s², h = 10 m)?
a) 9.8 m/s
b) 14 m/s
c) 20 m/s
d) 10 m/s