GCSE Physics: Forces and Motion 2 — Questions and Answers
Question 1: What is the unit of momentum in SI units?
- kg/m/s
- N/m
- kg·m/s (Correct answer)
- J/s
Correct answer: kg·m/s
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?
- 4 m/s
- 2 m/s (Correct answer)
- 8 m/s
- 1 m/s
Correct answer: 2 m/s
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?
- Speed
- Acceleration
- Distance travelled (Correct answer)
- Force
Correct answer: Distance travelled
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?
- Normal reaction
- Weight
- Air resistance (drag) (Correct answer)
- Friction from road
Correct answer: Air resistance (drag)
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?
- Weight is greater than drag.
- Drag is greater than weight.
- Weight and drag are equal. (Correct answer)
- There are no forces acting.
Correct answer: Weight and drag are equal.
At terminal velocity the resultant force is zero, meaning weight downward equals drag upward, so acceleration is zero.
Question 6: A force of 20 N acts on an object for 5 seconds. What is the impulse delivered to the object?
- 4 N·s
- 100 N·s (Correct answer)
- 25 N·s
- 15 N·s
Correct answer: 100 N·s
Impulse = Force × time = 20 N × 5 s = 100 N·s.
GCSE Physics: Forces and Motion 2
What is the unit of momentum in SI units?