WAEC Physics 2015 past questions

Checked by the Skolra question team · Last updated 23 October 2026

Ten questions from the 2015 WAEC Physics paper, with answers and explanations. We hold 40 questions from this paper, and the Skolra app has all of them.

WAEC Physics 2015 questions and answers

1. 1.The mass of the earth is 6.0 x 10²⁴kg and that of the moon is 7.0 x 10²²kg. If the distance between them is 4.0 x 10⁸m, calculate the force of attraction between them. [G = 6.7 x 10^-11Nm²kg^-2]
   1. A
      8.80 × 10¹⁹ N
   2. B
      3.52 × 10²⁰ N
   3. C
      4.41 × 10²⁰ N
   4. D
      1.76 × 10²⁰ N
      Correct
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   Answer: D

   Using Newton's law of universal gravitation: F = Gm₁m₂/r²
   F = (6.7 × 10⁻¹¹ × 6.0 × 10²⁴ × 7.0 × 10²²) / (4.0 × 10⁸)²
   Numerator = 6.7 × 6.0 × 7.0 × 10^{(−11+24+22)} = 281.4 × 10³⁵
   Denominator = 16 × 10¹⁶
   F = 281.4 × 10³⁵ / (16 × 10¹⁶) = 17.59 × 10¹⁹ ≈ 1.76 × 10²⁰ N

2. 2.Materials that can be stretched and still return to their original forms when the stresses are removed are said to be
   1. A
      Ductile
   2. B
      Malleable
   3. C
      Elastic
      Correct
   4. D
      Plastic
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   Answer: C

   Elastic materials return to their original shape and size after the deforming stress is removed, provided the elastic limit is not exceeded. This is described by Hooke's Law: F = ke, where k is the spring (elastic) constant and e is the extension. In contrast, plastic materials permanently retain their deformed shape; ductile materials can be drawn into wires; and malleable materials can be beaten into thin sheets.

3. 3.in a nuclear fission process, the mass defect was 1.2 x 10^-5kg. Calculate the energy released. [speed of the light in vacuum = c = 3.0 x 10⁸ms^-1]
   1. A
      1.08 × 10¹² J
      Correct
   2. B
      3.60 × 10¹² J
   3. C
      5.40 × 10¹¹ J
   4. D
      2.16 × 10¹² J
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   Answer: A

   Using Einstein's mass-energy equivalence: E = mc²
   m = 1.2 × 10⁻⁵ kg, c = 3.0 × 10⁸ m s⁻¹
   E = 1.2 × 10⁻⁵ × (3.0 × 10⁸)² = 1.2 × 10⁻⁵ × 9.0 × 10¹⁶ = 1.08 × 10¹² J
   This enormous energy release from a tiny mass illustrates why nuclear reactions release far more energy than chemical reactions.

4. 4.A body of mass 1000kg is released from a height of 10m above the ground. Determine its kinetic energy just before it strikes the ground .[g = 10ms^-2]
   1. A
      1.0 × 10⁵ J
      Correct
   2. B
      1.0 × 10⁴ J
   3. C
      1.0 × 10³ J
   4. D
      1.0 × 10⁶ J
   Show answerHide answer

   Answer: A

   By conservation of energy, all the gravitational potential energy converts to kinetic energy just before impact (neglecting air resistance):
   KE = PE = mgh
   KE = 1000 × 10 × 10 = 100,000 J = 1.0 × 10⁵ J
   
   Alternatively: using v² = 2gh = 2 × 10 × 10 = 200, v = √200 m/s, then KE = ½mv² = ½ × 1000 × 200 = 1.0 × 10⁵ J. Both methods confirm the same answer.

5. 5.An alternating current supply is connected to an electric lamp which lights with the same brightness as it does with direct current source emf 6v. The peak potential difference of the a.c supply is
   1. A
      6.0 V
   2. B
      3√2 V
   3. C
      12.0 V
   4. D
      6√2 V
      Correct
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   Answer: D

   When an AC source produces the same brightness as a DC source of 6 V, the rms (root mean square) value of the AC equals the DC emf: V_rms = 6 V. The peak (maximum) potential difference is related to the rms value by: V_peak = V_rms × √2 = 6√2 ≈ 8.49 V. Therefore the peak potential difference of the AC supply is 6√2 V.

6. 6.A uniform bar AB is balanced on a knife-edge which is 60cm from B by a mass of 22g which hangs at C 10cm from A. Calculate the mass of the bar.
   1. A
      88 g
   2. B
      55 g
   3. C
      66 g
      Correct
   4. D
      44 g
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   Answer: C

   Let the bar AB have length 100 cm.
   Knife-edge K is 60 cm from B ∴ K is at 40 cm from A.
   Mass 22 g hangs at C (10 cm from A) → C is 30 cm from K on the A-side.
   CG of the uniform bar is at 50 cm from A → CG is 10 cm from K on the B-side.
   
   Taking moments about K:
   Clockwise (22 g): 22 × 30 = 660 g cm
   Anti-clockwise (bar): m × 10
   660 = 10m ∴ m = 66 g

7. 7.The crackling noise produced by aluminum roofing sheets on a house during a hot sunny day is a result of
   1. A
      Thermal expansion and contraction of the aluminum sheets
      Correct
   2. B
      Strong winds causing the sheets to vibrate
   3. C
      Condensation of atmospheric water vapor on the sheets
   4. D
      Acoustic resonance within the sheets
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   Answer: A

   Aluminum has a relatively high coefficient of linear expansion (≈ 23 × 10⁻⁶ K⁻¹). On a hot sunny day, the sheets absorb solar radiation and expand. As temperatures fluctuate — particularly during heating in the morning and cooling in the evening — the sheets expand and contract, causing them to buckle and snap against their fixings and against each other, producing the characteristic crackling noise. This is a direct manifestation of thermal expansion.

8. 8.An object is placed 15cm from a diverging lens of focal length 1cm. The image of the object formed by the lens in
   1. A
      virtual, erect and diminished
      Correct
   2. B
      real, inverted and diminished
   3. C
      real, erect and magnified
   4. D
      virtual, inverted and magnified
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   Answer: A

   A diverging (concave) lens always has a negative focal length. Using the lens formula 1/f = 1/v − 1/u with f = −1 cm and u = −15 cm gives v ≈ −0.94 cm. The negative image distance confirms the image is virtual (on the same side as the object). Since |v| < |u|, the image is diminished, and because u and v share the same sign, the image is erect. A diverging lens always forms a virtual, erect, and diminished image for any real object position, regardless of where the object is placed.

9. 9.Which of the following radiations constitutes a stream of electrons?
   1. A
      Alpha (α) rays
   2. B
      X-rays
   3. C
      Gamma (γ) rays
   4. D
      Beta (β) rays
      Correct
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   Answer: D

   Beta (β⁻) radiation consists of a stream of high-speed electrons emitted from the nucleus when a neutron converts to a proton (n → p + e⁻ + antineutrino). Alpha particles are helium nuclei (2 protons + 2 neutrons), while gamma rays and X-rays are electromagnetic radiation (photons) with no charge or mass. Only β-rays constitute a stream of electrons.

10. 10.An object floats in a fluid when it displaces it's
    1. A
       Half its weight in the fluid
    2. B
       Twice its weight in fluid
    3. C
       Its own weight in fluid
       Correct
    4. D
       Its own volume in fluid
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    Answer: C

    By Archimedes' principle, the upthrust (buoyant force) on a body equals the weight of fluid it displaces. A body floats when the upthrust equals its own weight, meaning it must displace fluid whose weight equals its own weight. This is why a steel ship floats — by its hollow shape it displaces a weight of water equal to its total weight, even though steel is denser than water.

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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