A man carries a 1kg body 10m horizontally on a level ground. The work done by man is :
Correct answer: C. 0 J
- A. 10 J
- B. 1 J
- C. 0 J
- D. 5 J
Explanation
To calculate work done, the formula is Work = Force × Displacement × cos(θ), where θ is the angle between the force and displacement vectors. In this scenario, the force due to gravity acts vertically downwards, and the displacement is horizontal. Since these two directions are perpendicular, θ = 90 degrees, and cos(90°) = 0. Thus, the work done is 0 J as there is no component of the force in the direction of displacement. The other options are incorrect because they assume a non-existent horizontal force component.
This question appeared on the ETEA MDCAT 2008 paper, which you can sit online with every answer explained.
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About Work
Work is done when a force produces displacement, with its value determined by the component of force along the displacement. The topic covers positive, negative and zero work, work by variable forces from force-displacement graphs, and the connection between net work and change in kinetic energy.
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