GCSE Physics: Forces and Motion 2

Question 1

What is the unit of momentum in SI units?

Accepted Answer

kg·m/s

Answer

Momentum = mass × velocity, so its SI unit is kg·m/s (kilogram metres per second).

Question 2

A 2 kg object travelling at 4 m/s collides and sticks to a stationary 2 kg object. What is their combined speed after the collision?

Accepted Answer

2 m/s

Answer

By conservation of momentum: 2×4 = 4×v, so v = 8/4 = 2 m/s.

Question 3

What does the area under a velocity-time graph represent?

Accepted Answer

Distance travelled

Answer

The area under a velocity-time graph gives the displacement (distance travelled) of the object.

Question 4

Which force opposes the motion of a car moving through air?

Accepted Answer

Air resistance (drag)

Answer

Air resistance (drag) is the force that acts opposite to the direction of motion of an object moving through air.

Question 5

At terminal velocity, what can be said about the forces on a falling object?

Accepted Answer

Weight and drag are equal.

Answer

At terminal velocity the resultant force is zero, meaning weight downward equals drag upward, so acceleration is zero.

GCSE - General Certificate of Secondary Education Practice Test