A-Level H2 Physics 1 — Questions and Answers
Question 1: A ball is thrown horizontally from a height of 20m. Taking g = 10 m/s², how long does it take to reach the ground?
- 1s
- 2s (Correct answer)
- 4s
- √2 s
Correct answer: 2s
Using h = ½gt²: 20 = ½×10×t². t² = 4. t = 2s. Horizontal motion is independent of vertical free fall.
Question 2: What is the work-energy theorem?
- Work = Force × Distance
- The net work done on an object equals its change in kinetic energy (Correct answer)
- Total energy is conserved in all reactions
- Work is always positive
Correct answer: The net work done on an object equals its change in kinetic energy
The work-energy theorem states that the net work done on an object equals its change in kinetic energy: W_net = ΔKE = ½mv² - ½mu².
Question 3: State Newton's Third Law of Motion.
- F = ma
- Every action has an equal and opposite reaction acting on the same object
- Every action has an equal and opposite reaction acting on different objects (Correct answer)
- Objects at rest remain at rest
Correct answer: Every action has an equal and opposite reaction acting on different objects
Newton's Third Law: for every action force, there is an equal and opposite reaction force, acting on DIFFERENT objects. The forces are equal in magnitude but act on different bodies.
Question 4: A spring with spring constant k = 200 N/m is compressed by 0.05 m. What is the elastic potential energy stored?
- 0.25 J (Correct answer)
- 0.5 J
- 5 J
- 10 J
Correct answer: 0.25 J
E = ½kx² = ½ × 200 × (0.05)² = 100 × 0.0025 = 0.25 J.
Question 5: What is the principle of superposition of waves?
- Two waves cannot occupy the same space
- When two waves meet, the resultant displacement is the vector sum of individual displacements (Correct answer)
- Waves always cancel each other out
- Waves travel faster when combined
Correct answer: When two waves meet, the resultant displacement is the vector sum of individual displacements
The principle of superposition states that when two or more waves overlap, the resultant displacement at any point is the algebraic (vector) sum of the individual displacements.
Question 6: What is meant by 'terminal velocity'?
- The maximum possible speed in a vacuum
- The constant velocity reached when drag force equals driving force (or weight) (Correct answer)
- The velocity at which an object stops
- Initial velocity of a thrown object
Correct answer: The constant velocity reached when drag force equals driving force (or weight)
Terminal velocity is the constant velocity reached by a falling object when the upward drag force equals the downward weight, so net force = 0 and acceleration = 0.
A-Level H2 Physics 1
A ball is thrown horizontally from a height of 20m.
Taking g = 10 m/s², how long does it take to reach the ground?