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Sunday, 21 June 2026
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Physics Past Questions and Answers

Topic: Conservation of energy

Jamb Physics Questions - Conservation of energy

Question 1:
Which of the following statements defines correctly the efficiency of a machine?
  • A The load carried by the machine divided by effort required in carrying the load
  • B The distance moved by the load divided by the distance moved by the effort
  • C The useful work done by the machine divided by the total work put into the machine
  • D The movement of the load divided by the movement of the effort about the same point
  • E The temperature at the end of the application of the machine divided by the initial temperature
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Question 2:
A block-and-tackle system is used to lift a load of 20N through a vertical height of 10m. if the efficiency of the system is 40%, how much work is done against friction?
  • A 80J
  • B 120J
  • C 300J
  • D 500J
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Question 3:
An object of mass 50kg is released from a height of 2m.Find the kinetic energy just before it strikes the ground
  • A 250J
  • B 1000J
  • C 10 000J
  • D 100 000J
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Question 4:
The efficiency of a machine is always less than 100% because the
  • A Work output is always greater than the work input
  • B Load lifted is always greater than the effort applied
  • C Effort applied is always greater than the load lifted
  • D Velocity ratio is always greater than the mechanical advantage
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Question 5:
The maximum kinetic energy of the photoelectron emitted from a metal surface is 0.34eV. If the work function of the metal surface is 1.83eV,find the stopping potential.
  • A 2.17V
  • B 1.49V
  • C 1.09V
  • D 0.34V
View Answer & Explanation