Momentum

Question 1

The formula for momentum is:

Accepted Answer

p = mv — Momentum is the product of mass and velocity, p = mv.

Question 2

The SI unit of momentum is:

Accepted Answer

kg m s⁻¹ — p = mv, so units are kg × m s⁻¹ = kg m s⁻¹.

Question 3

The momentum of a 4 kg object moving at 5 m s⁻¹ is:

Accepted Answer

20 kg m s⁻¹ — p = mv = 4 × 5 = 20 kg m s⁻¹.

Question 4

Momentum is a:

Accepted Answer

Vector quantity — Momentum has magnitude and direction, so it is a vector.

Question 5

In a closed system with no external force, total momentum is:

Accepted Answer

Conserved — The principle of conservation of momentum keeps total momentum constant.

Question 6

A 3 kg trolley at 4 m s⁻¹ hits and sticks to a stationary 1 kg trolley. Common velocity is:

Accepted Answer

3 m s⁻¹ — (3×4) = (3+1)v, 12 = 4v, v = 3 m s⁻¹.

Question 7

A collision where the objects bounce apart is called:

Accepted Answer

An elastic collision — In an elastic collision the objects separate after impact.

Question 8

Before an explosion the total momentum of a stationary object is:

Accepted Answer

Zero — A stationary object has zero total momentum before exploding.

Question 9

Two identical trolleys of 2 kg move toward each other at 3 m s⁻¹ and stick together. Their common velocity is:

Accepted Answer

0 m s⁻¹ — Momenta +6 and −6 cancel; total = 0, so v = 0.

Question 10

Doubling the velocity of an object (same mass) changes its momentum to:

Accepted Answer

Double — p = mv, so doubling v doubles momentum.