QUESTIONS AND CORRECT ANSWERS WITH RATIONALES COVERING
THE RECENT TESTED QUESTIONS PERFECT FOR HIGH PASSMARK
Question 1:
A car of mass 1,200 kg accelerates from 0 to 10 m/s in 5 seconds. Calculate the acceleration.
Answer:
𝑣 − 𝑢 10 − 0
𝑎= = = 2 m/s²
𝑡 5
Δ𝑣
Rationale: Acceleration is the change in velocity over time; formula 𝑎 = .
𝑡
Question 2:
A light ray passes from air into glass. Describe what happens.
Answer:
The light slows down and bends towards the normal.
Rationale: Refraction occurs because light changes speed between materials of different optical
density.
Question 3:
An object weighing 50 N is lifted 2 m vertically. Calculate the work done.
Answer:
𝑊 = 𝐹 × 𝑑 = 50 × 2 = 100 J
Rationale: Work done is force multiplied by distance in the direction of the force.
Question 4:
State Newton’s Third Law.
Answer:
For every action, there is an equal and opposite reaction.
,Rationale: Forces always occur in pairs; the action and reaction forces act on different bodies.
Question 5:
A circuit contains a 12 V battery and a resistor of 4 Ω. Calculate the current.
Answer:
𝑉 12
𝐼= = =3A
𝑅 4
Rationale: Ohm’s law 𝑉 = 𝐼 × 𝑅relates voltage, current, and resistance.
Question 6:
Explain why metals are good conductors of electricity.
Answer:
Metals have free electrons that can move through the lattice and carry charge.
Rationale: Conductivity depends on the availability of mobile charge carriers.
Question 7:
A spring extends by 0.05 m when a force of 10 N is applied. Calculate the spring constant.
Answer:
𝐹 10
𝑘= = = 200 N/m
𝑥 0.05
Rationale: Hooke’s Law: 𝐹 = 𝑘𝑥, where k is the spring constant.
Question 8:
A wave has a frequency of 50 Hz and a wavelength of 2 m. Calculate the wave speed.
Answer:
𝑣 = 𝑓 × 𝜆 = 50 × 2 = 100 m/s
Rationale: Wave speed = frequency × wavelength.
,Question 9:
Describe the difference between transverse and longitudinal waves.
Answer:
• Transverse: Oscillations are perpendicular to wave direction.
• Longitudinal: Oscillations are parallel to wave direction.
Rationale: Examples: light is transverse, sound is longitudinal.
Question 10:
A car travels 100 km in 2 hours. Calculate its average speed.
Answer:
𝑑 100
𝑣= = = 50 km/h
𝑡 2
Rationale: Average speed = total distance ÷ total time.
Question 11:
Explain why astronauts feel weightless in orbit.
Answer:
They are in free fall, accelerating towards Earth, but moving tangentially, so there is no normal
force.
Rationale: Weightlessness occurs because all objects accelerate at the same rate under gravity.
Question 12:
A circuit has two resistors in series: 3 Ω and 6 Ω. Calculate the total resistance.
Answer:
𝑅total = 3 + 6 = 9 Ω
Rationale: Series resistances add directly.
Question 13:
Describe the energy changes when a ball is dropped from a height.
, Answer:
Gravitational potential energy → kinetic energy → thermal energy on impact.
Rationale: Energy is conserved and transforms between forms.
Question 14:
State the equation linking force, mass, and acceleration.
Answer:
𝐹 = 𝑚×𝑎
Rationale: Newton’s Second Law defines the relationship between force, mass, and
acceleration.
Question 15:
A 60 W bulb is connected to a 230 V supply. Calculate the current.
Answer:
𝑃 60
𝐼= = ≈ 0.26 A
𝑉 230
Rationale: Electrical power 𝑃 = 𝑉 × 𝐼.
Question 16:
Explain why sound cannot travel in a vacuum.
Answer:
Sound is a mechanical wave and requires particles to transmit vibrations.
Rationale: No particles → no medium → no sound transmission.
Question 17:
A car moving at 20 m/s hits brakes and stops in 5 seconds. Calculate its deceleration.
Answer:
𝑣 − 𝑢 0 − 20
𝑎= = = −4 m/s²
𝑡 5