A 5 kg block is moved from the rest through a distance of 4 m along the x-direction. A force equal to 20 N acts on it. If the block acquires a K.E. equal to 40 J, what is the angle the force makes with x-axis?
Correct answer: D. 60o
- A. 0o
- B. 30o
- C. 45o
- D. 60o
Explanation
By work energy principle Work = K.E Fdcosθ = K.E cosθ = K.E/Fd = 40/(20)(4) = 1/2 θ = cos-1(1/2) = 60o
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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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