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Free Work-Energy Theorem MCQs with Answers

26 Work-Energy Theorem MCQs from Physics, each with the correct answer and a written explanation of why it is correct. Free and unlimited, with no account needed.

The work-energy theorem states that the net work done on an object equals its change in kinetic energy. Questions involve positive and negative work, variable forces and force-displacement graphs, acceleration or deceleration, and the difference between this theorem and conservation of mechanical energy, which also requires attention to potential energy and non-conservative work.

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26 questions · page 2 of 2

21. A steel ball of mass 5 g is thrown downward with velocity 10 m/s from height 19.5m. It penetrates sand by 50 cm. The change in mechanical energy will be: (g = 10 m/s2).

  • A. 1J
  • B. 1.25J
  • C. 1.5J
  • D. l.75J

Explanation: Mass, m = 5g = 0.005 Kgh = 19.5 mx = 50 cm = 0.5 mv = 10 m/sThe change in the mechanical energy, ΔU = mg(h+x) + (1/2)mv2= 0.005 x 10(19.5…

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Correct answer: 1.25J

22. The effect of work is equal to

  • A. Change in total energy
  • B. Change in kinetic energy
  • C. Change in power
  • D. None of these

Explanation: The work-energy theorem states that the net work done by the forces on an object equals the change in its kinetic energy.

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Correct answer: Change in kinetic energy

23. A particle of mass 10 kg is moving with velocity 10 (x)^1/2, here x is displacement. The work done by net force during the displacement of particle from x=4 to x=9

  • A. 1250J
  • B. 1000J
  • C. 1500J
  • D. 2500J

Explanation: Given : m= 10 kg v= 10√x m/s and dv/dx = 5/√x Now we know the formula; w= ma w= m(dv/dt) = m(dv/dt)(dx/dx) w= mv (dv/dx) Now we will apply…

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Correct answer: 2500J

24. The effect of work done is equal to

  • A. Change in total energy
  • B. Change in kinetic energy
  • C. Change in power
  • D. None of these options are correct

Explanation: The work-energy theorem states that the net work done by the forces on an object equals the change in its kinetic energy.

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Correct answer: Change in kinetic energy

25. If a certain force acts on an object and changes its kinetic energy from 65 J to 130 J, then work done by the force will be:

  • A. 92.5 J
  • B. 97.5 J
  • C. 65 J
  • D. 130 J

Explanation: Explanation:Final Kinetic energy (K.Ef) = 130 JInitial Kinetic energy (K.Ei) = 65 JWorkdone = W = ?As we know that: W = K.Ef - K.Ei = 130…

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Correct answer: 65 J

26. A 2kg object is released from rest 8m above the surface of the Earth, During the fall work done against air resistance is 60J. Just before it hits the surface its speed is: (Hint-take g=10 m/sec2)

  • A. 10 m/sec
  • B. 36 m/sec
  • C. 40 m/sec
  • D. 45 m/sec

Explanation: To solve the problem, we first calculate the gravitational potential energy (PE) of the object when it is released from a height of 8 m.

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Correct answer: 10 m/sec
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