NSAA NSAA Physics - Mechanics 1 — Questions and Answers
Question 1: A ball is thrown vertically upward with an initial velocity of 20 m/s. What is the maximum height reached (g = 10 m/s²)?
- 10 m
- 20 m (Correct answer)
- 40 m
- 5 m
Correct answer: 20 m
Using v² = u² - 2gh, with v=0 at maximum height: h = u²/2g = 400/20 = 20 m.
Question 2: A 5 kg block slides down a frictionless incline of 30°. What is its acceleration?
- 4.9 m/s² (Correct answer)
- 8.5 m/s²
- 9.8 m/s²
- 2.5 m/s²
Correct answer: 4.9 m/s²
The component of gravity along the incline is g sin30° = 9.8 × 0.5 = 4.9 m/s².
Question 3: Two objects of mass 3 kg and 5 kg collide and stick together. If the 3 kg object was moving at 8 m/s and the 5 kg was stationary, what is the final velocity?
- 3 m/s (Correct answer)
- 4 m/s
- 5 m/s
- 2 m/s
Correct answer: 3 m/s
By conservation of momentum: 3×8 = (3+5)v, so v = 24/8 = 3 m/s.
Question 4: A car of mass 1000 kg accelerates from rest to 20 m/s in 10 s. What net force acts on it?
- 500 N
- 1000 N
- 2000 N (Correct answer)
- 200 N
Correct answer: 2000 N
Acceleration = 20/10 = 2 m/s²; F = ma = 1000 × 2 = 2000 N.
Question 5: A spring of spring constant 200 N/m is compressed by 0.05 m. What is the elastic potential energy stored?
- 0.25 J (Correct answer)
- 0.50 J
- 1.00 J
- 0.10 J
Correct answer: 0.25 J
Elastic PE = ½kx² = ½ × 200 × (0.05)² = 0.25 J.
Question 6: An object moves in a circle of radius 2 m at a speed of 4 m/s. What is its centripetal acceleration?
- 2 m/s²
- 4 m/s²
- 8 m/s² (Correct answer)
- 16 m/s²
Correct answer: 8 m/s²
Centripetal acceleration a = v²/r = 16/2 = 8 m/s².
NSAA NSAA Physics - Mechanics 1
A ball is thrown vertically upward with an initial velocity of 20 m/s.
What is the maximum height reached (g = 10 m/s²)?