NSAA NSAA Physics - Mechanics 3

Question 1

What is the impulse on a 2 kg object that changes velocity from 3 m/s to 9 m/s?

Accepted Answer

12 N·s

Answer

Impulse = Δ(mv) = m×Δv = 2×(9-3) = 12 N·s.

Question 2

A 10 kg box is pushed along a horizontal surface by a 40 N force. If friction is 15 N, what is the acceleration?

Accepted Answer

2.5 m/s²

Answer

Net force = 40 - 15 = 25 N; a = F/m = 25/10 = 2.5 m/s².

Question 3

Two forces of 6 N and 8 N act at right angles on an object. What is the resultant force?

Accepted Answer

10 N

Answer

Resultant = √(6² + 8²) = √(36+64) = √100 = 10 N.

Question 4

A machine does 600 J of work in 30 seconds. What is its power output?

Accepted Answer

20 W

Answer

Power = Work/Time = 600/30 = 20 W.

Question 5

If the velocity of an object doubles, by what factor does its kinetic energy increase?

Accepted Answer

4

Answer

KE = ½mv², so doubling v multiplies KE by v² factor = 2² = 4.

NSAA - Natural Sciences Admissions Assessment Practice Test