Physics Mechanics 2

Question 1

A 5 kg box slides down a frictionless incline angled at 30° to the horizontal. What is the acceleration of the box?

Accepted Answer

4.9 m/s²

Answer

Acceleration on a frictionless incline is g·sin(θ) = 9.8 × sin(30°) = 9.8 × 0.5 = 4.9 m/s².

Question 2

A car traveling at 20 m/s applies brakes and decelerates at 4 m/s². How long does it take to stop?

Accepted Answer

5 s

Answer

Using v = v₀ + at: 0 = 20 + (−4)t → t = 5 s.

Question 3

Which of the following is a vector quantity?

Accepted Answer

Displacement

Answer

Displacement has both magnitude and direction, making it a vector; speed, mass, and temperature are scalars.

Question 4

Two objects of masses 3 kg and 6 kg collide and stick together. If the 3 kg object was moving at 4 m/s and the 6 kg object was at rest, what is their combined velocity after collision?

Accepted Answer

1.33 m/s

Answer

By conservation of momentum: (3)(4) = (3+6)v → v = 12/9 ≈ 1.33 m/s.

Question 5

A projectile is launched horizontally from a cliff. Which statement about its motion is correct?

Accepted Answer

Horizontal and vertical motions are independent

Answer

Horizontal and vertical components of projectile motion are independent; gravity affects only the vertical component.

Physics Practice Test

Physics Practice Test

Physics Mechanics 2