WAEC Physics questions: Work, energy and power

14 questions with answers and explanations. Tap an option to check yourself.

1. Question 1· Work, energy and power· WAEC

   As a stone falls freely towards the ground, its

   • Atotal energy becomes zero
   • Bkinetic energy decreases
   • Cpotential energy increases
   • Dpotential energy decreases and kinetic energy increases

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   Explanation and discussion

2. Question 2· Work, energy and power· WAEC

   A pendulum bob at the lowest point of its swing has maximum

   • Apotential energy
   • Bkinetic energy
   • Cheight
   • Dacceleration

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   Explanation and discussion

3. Question 3· Work, energy and power· WAEC

   Work done by a force is zero when the force is

   • Aperpendicular to the displacement
   • Bparallel to the displacement
   • Cvery large
   • Dconstant

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   Explanation and discussion

4. Question 4· Work, energy and power· WAEC

   A 50 kg boy climbs a 4 m staircase in 8 s. His power is (g = 10 m/s²)

   • A250 W
   • B2,000 W
   • C100 W
   • D1,600 W

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   Explanation and discussion

5. Question 5· Work, energy and power· WAEC

   A pump raises 300 kg of water through 10 m in 60 s. Find its power. [g = 10 m/s²]

   • A50 W
   • B30 000 W
   • C500 W
   • D1800 W

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   Explanation and discussion

6. Question 6· Work, energy and power· WAEC

   A boy of mass 50 kg climbs a staircase 4 m high in 10 s. His power is (g = 10 m/s²)

   • A200 W
   • B2000 W
   • C20 W
   • D500 W

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   Explanation and discussion

7. Question 7· Work, energy and power· WAEC

   A force of 20 N moves a box through 5 m in the direction of the force. The work done is

   • A4 J
   • B25 J
   • C100 J
   • D15 J

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8. Question 8· Work, energy and power· WAEC

   A pump raises 100 kg of water through 6 m in 30 s. Find its power. (g = 10 m/s²)

   • A6,000 W
   • B20 W
   • C200 W
   • D18,000 W

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   Explanation and discussion

9. Question 9· Work, energy and power· WAEC

   A ball of mass 0.5 kg moves at 4 m/s. Its kinetic energy is

   • A1 J
   • B8 J
   • C2 J
   • D4 J

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10. Question 10· Work, energy and power· WAEC

    The kinetic energy of a 4 kg body moving at 3 m/s is

    • A12 J
    • B18 J
    • C36 J
    • D6 J

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    Explanation and discussion

11. Question 11· Work, energy and power· WAEC

    When a body falls freely, its

    • Akinetic energy changes into potential energy
    • Bpotential energy changes into kinetic energy
    • Ctotal energy increases
    • Dmass increases

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    Explanation and discussion

12. Question 12· Work, energy and power· WAEC

    A boy lifts a 25 kg bag through a height of 2 m. How much work does he do? [g = 10 m/s²]

    • A250 J
    • B50 J
    • C500 J
    • D5000 J

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13. Question 13· Work, energy and power· WAEC

    In a dynamo the main energy change is from

    • Aelectrical to mechanical
    • Bmechanical to electrical
    • Cchemical to electrical
    • Dheat to electrical

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    Explanation and discussion

14. Question 14· Work, energy and power· WAEC

    Find the kinetic energy of a 2 kg mass moving at 6 m/s.

    • A18 J
    • B12 J
    • C72 J
    • D36 J

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    Explanation and discussion