5) If a body of mass of 2 kg is raised vertically through 2m, then the work done will be: (Work, Power & Energy, Work Done by Constant Force and Variable forces)
Correct answer: C. 39.2 J
- A. 38.2 J
- B. 392j
- C. 39.2 J
- D. 3.92 J
Explanation
Reasoning: Work done (W) = Fd cos θ, where F is the force, d is the displacement, and θ is the angle between them. In this case, F = mg (weight of the body), d = 2 m (vertical distance), θ = 0° (force and displacement in the same direction), and g ≈ 9.81 m/s² (acceleration due to gravity). Therefore, W = (2 kg * 9.81 m/s²) * 2 m ≈ 39.2 J.Incorrect Options:(a) This is slightly off due to rounding errors in calculations.(b) This is a significant overestimation. It might be due to misinterpreting the units or miscalculating the force involved.(d) This is a substantial underestimation. It could be caused by confusion regarding the weight of the body or neglecting the gravitational acceleration value.
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About Work and Energy
Work transfers energy when a force causes displacement, while kinetic energy, gravitational potential energy and power describe motion, position and the rate of energy transfer. The work-energy theorem links net work with change in kinetic energy, and efficiency accounts for energy losses rather than treating them as energy destruction.
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