NSAA NSAA Physics - Mechanics 2 — Questions and Answers
Question 1: A projectile is launched horizontally at 15 m/s from a height of 20 m. How long does it take to hit the ground (g = 10 m/s²)?
- 1 s
- 2 s (Correct answer)
- 3 s
- 4 s
Correct answer: 2 s
Using h = ½gt²: 20 = ½×10×t², giving t² = 4, so t = 2 s.
Question 2: What is the momentum of a 0.5 kg ball moving at 12 m/s?
- 3 kg·m/s
- 6 kg·m/s (Correct answer)
- 12 kg·m/s
- 24 kg·m/s
Correct answer: 6 kg·m/s
Momentum p = mv = 0.5 × 12 = 6 kg·m/s.
Question 3: A force of 50 N acts on an object over a displacement of 8 m in the direction of the force. What work is done?
- 200 J
- 300 J
- 400 J (Correct answer)
- 600 J
Correct answer: 400 J
Work = Force × displacement = 50 × 8 = 400 J.
Question 4: A pulley system has a mechanical advantage of 4. What input force is needed to lift a 200 N load?
- 25 N
- 50 N (Correct answer)
- 100 N
- 800 N
Correct answer: 50 N
Input force = Load / MA = 200 / 4 = 50 N.
Question 5: An object of weight 60 N is held stationary on a surface. What is the normal reaction force from the surface?
- 0 N
- 30 N
- 60 N (Correct answer)
- 120 N
Correct answer: 60 N
By Newton's third law, the normal force equals the weight when the object is in equilibrium on a horizontal surface.
Question 6: A 2 kg mass is raised 5 m vertically. What is the gain in gravitational potential energy (g = 10 m/s²)?
- 10 J
- 50 J
- 100 J (Correct answer)
- 200 J
Correct answer: 100 J
GPE = mgh = 2 × 10 × 5 = 100 J.
NSAA NSAA Physics - Mechanics 2
A projectile is launched horizontally at 15 m/s from a height of 20 m.
How long does it take to hit the ground (g = 10 m/s²)?