WAEC Physics 1998 past questions

Checked by the Skolra question team · Last updated 15 October 2026

Ten questions from the 1998 WAEC Physics paper, with answers and explanations. We hold 48 questions from this paper, and the Skolra app has all of them.

WAEC Physics 1998 questions and answers

1.An object is protected with a velocity of 100m-1 at an angle of 60o to the vertical. Calculate the time taken by the object to reach the highest point (Take g as 10ms-2)
1. A
  8.7 s
2. B
  5 s
  Correct
3. C
  7.1 s
4. D
  10 s
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Answer: B
The angle of projection is 60° to the vertical, which means it is 30° to the horizontal.
Vertical component of initial velocity:
u_y = 100 × cos 60° = 100 × 0.5 = 50 m/s
At the highest point, vertical velocity = 0. Using v = u − gt:
0 = 50 − 10t
t = 5 s
2.A body moving in a circle at constant speed has i. a velocity tangent to the circle ii. a constant kinetic energy ii. an acceleration directed towards the circumference of the circle. Which of the statements above are correct?
1. A
  i only
2. B
  ii and iii only
3. C
  i, ii and iii
4. D
  i and ii only
  Correct
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Answer: D
For a body in uniform circular motion (constant speed):
Statement i: Velocity is always tangential to the circle — TRUE.
Statement ii: Kinetic energy = ½mv²; since speed is constant, KE is constant — TRUE.
Statement iii: Centripetal acceleration is directed towards the centre of the circle, not the circumference — FALSE.
Only statements i and ii are correct.
3.The phenomenon which occurs when light changes direction as it passes from one medium to another is called
1. A
  dispersion
2. B
  refraction
  Correct
3. C
  reflection
4. D
  diffraction
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Answer: B
Refraction is the phenomenon in which light (or any wave) changes direction as it passes from one medium to another of different optical density. This occurs because the speed of light changes between media.
The degree of bending is described by Snell's Law: n₁ sin θ₁ = n₂ sin θ₂.
4.A body of mass 200g and specific heat capacity 0.4Jg-1k-1 cools from 37oC to 31oC. Calculate the quantity of the heat released by the body.
1. A
  600 J
2. B
  480 J
  Correct
3. C
  240 J
4. D
  360 J
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Answer: B
Using the heat equation: Q = mcΔT
Q = 200 g × 0.4 J g⁻¹ K⁻¹ × (37 − 31) K
Q = 200 × 0.4 × 6 = 480 J
5.A 90-W immersion heater is used to supply energy for five minutes. The energy supplied is used to completely melt 180g of a solid at is melting point. Neglecting energy losses to the surroundings, calculate the specific latent heat of fusion of the solid
1. A
  3.0 × 10⁵ J kg⁻¹
2. B
  7.5 × 10⁴ J kg⁻¹
3. C
  2.7 × 10⁴ J kg⁻¹
4. D
  1.5 × 10⁵ J kg⁻¹
  Correct
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Answer: D
Energy supplied by the heater:
Q = P × t = 90 W × (5 × 60 s) = 90 × 300 = 27 000 J
This energy melts 180 g = 0.180 kg of solid. Using Q = mL:
L = Q / m = 27 000 / 0.180 = 150 000 J kg⁻¹ = 1.5 × 10⁵ J kg⁻¹
6.Lenz's law of electromagnet states that
1. A
  the force on a current-carrying conductor is proportional to the current and flux density
2. B
  the induced e.m.f. is directly proportional to the rate of change of magnetic flux
3. C
  the induced e.m.f. acts in a direction so as to oppose the change causing it
  Correct
4. D
  the mutual inductance between two coils depends only on their geometry
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Answer: C
Lenz's Law states that the direction of an induced e.m.f. is always such that it opposes the change in magnetic flux that produces it. This is a statement of energy conservation — the induced current creates a magnetic field that resists the changing flux.
Option (b) describes Faraday's Law, which gives the magnitude (not direction) of the induced e.m.f.: E = −dΦ/dt.
7.A piece of metal is heated until it becomes red-hot, it is then quickly transferred into a beaker containing boiling water. What effect will this have on the boiling water?
1. A
  it will cause more of the water to vaporise
  Correct
2. B
  it will raise the temperature of the water above 100°C
3. C
  it will cause the water to cool down and stop boiling
4. D
  it will have no effect on the water
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Answer: A
The water is already at its boiling point (100°C at atmospheric pressure). The red-hot metal is above 100°C, so it supplies heat to the water. However, water at 100°C cannot rise above 100°C at atmospheric pressure — the additional heat energy is used as latent heat of vaporisation.
Therefore, the effect is that more water is converted to steam (vaporises), making the boiling more vigorous.
8.A ball of mass 5.0kg hits a smooth vertical wall normally with a speed of 2ms-1 and rebounds with the same speed. Determine the impulse experienced by the ball
1. A
  20 Ns
  Correct
2. B
  5 Ns
3. C
  40 Ns
4. D
  10 Ns
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Answer: A
Impulse = change in momentum = m(v − u)
Taking the direction away from the wall as positive:
Initial momentum = 5.0 × (−2) = −10 kg m s⁻¹ (towards wall)
Final momentum = 5.0 × (+2) = +10 kg m s⁻¹ (away from wall)
Impulse = 10 − (−10) = 20 Ns
9.Air at temperature 527oC and pressure 30 atmospheres is admitted into the cylinder of an engine. Calculate the pressure of the gas when it has expanded to 5 times its volume and cooled to 127oC as it leaves the engine
1. A
  1.5 atm
2. B
  3 atm
  Correct
3. C
  6 atm
4. D
  12 atm
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Answer: B
Using the combined gas law: P₁V₁/T₁ = P₂V₂/T₂
Given: P₁ = 30 atm, T₁ = 527 + 273 = 800 K, V₁ = V
T₂ = 127 + 273 = 400 K, V₂ = 5V
P₂ = P₁V₁T₂ / (T₁V₂) = (30 × V × 400) / (800 × 5V)
P₂ = 12 000 / 4 000 = 3 atm
10.Which of the following explains the concave meniscus of water in a glass tube?
1. A
  The cohesive force between water molecules is greater than the adhesive force between water and glass
2. B
  Water has a higher viscosity than most common liquids
3. C
  The surface tension of water is extremely high
4. D
  The adhesive force between water and glass is greater than the cohesive force between water molecules
  Correct
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Answer: D
Water forms a concave meniscus in a glass tube because the adhesive force between water molecules and glass molecules exceeds the cohesive force between water molecules.
Water molecules are more attracted to the glass surface than to each other, causing the liquid surface to curve upward at the walls. This same imbalance also drives capillary rise of water in narrow glass tubes.

The questions come from past JAMB, WAEC and NECO papers. We use software to help write the answer options and explanations, and every answer is checked twice before it goes on the site. How we check

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WAEC Physics 1998 past questions

WAEC Physics 1998 questions and answers

Practise all 48 questions we hold from the 1998 paper, on a timed CBT screen

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