41. A 5 kg block is pushed with a force of 20 N. If friction is 5 N, what is its acceleration?
a) 3 m/s²
b) 4 m/s²
c) 5 m/s²
d) 2 m/s²
42. A force of 50 N is applied on a 25 kg cart for 5 seconds. What is the final velocity if it starts from rest?
a) 10 m/s
b) 5 m/s
c) 2 m/s
d) 20 m/s
43. A 3 kg object moving at 6 m/s collides with a 2 kg object at rest. What is the velocity of the system after collision (elastic collision not assumed)?
a) 3.6 m/s
b) 2.4 m/s
c) 4.2 m/s
d) 5.2 m/s
44. A bullet of mass 0.02 kg is fired with a velocity of 300 m/s. What is its kinetic energy?
a) 600 J
b) 900 J
c) 1000 J
d) 1200 J
45. A machine does 5000 J of work in 10 seconds. What is its power output?
a) 250 W
b) 500 W
c) 1000 W
d) 5000 W
46. A 60 kg person jumps from a height of 5 m. What is their potential energy just before jumping? (g = 9.8 m/s²)
a) 3000 J
b) 2000 J
c) 4000 J
d) 6000 J
47. A 5 kg object moving at 10 m/s collides with a wall and stops in 0.2 seconds. What is the force exerted by the wall?
a) 250 N
b) 500 N
c) 100 N
d) 200 N
(Impulse = change in momentum = m(v – u) = 5(0 – 10) = -50 kg·m/s, Force = Impulse/time = 50/0.2 = 500 N)
48. If a car of mass 1200 kg is moving with a velocity of 25 m/s, what is its momentum?
a) 30,000 kg·m/s
b) 25,000 kg·m/s
c) 20,000 kg·m/s
d) 15,000 kg·m/s
49. A 20 N force is applied to a 4 kg object at rest. What is its velocity after 3 seconds?
a) 10 m/s
b) 12 m/s
c) 15 m/s
d) 20 m/s
50. A box of mass 10 kg is pushed with a force of 40 N over a rough surface with a friction force of 10 N. What is its acceleration?
a) 2 m/s²
b) 3 m/s²
c) 4 m/s²
d) 5 m/s²