A block is projected up a rough incline of angle 37°. Coefficient of kinetic friction is 0.25. Take sin37° = 3/5 and cos37° = 4/5. The ratio of magnitude of acceleration while moving up to that while moving down is:
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Question

A block is projected up a rough incline of angle 37°. Coefficient of kinetic friction is 0.25. Take sin37° = 3/5 and cos37° = 4/5. The ratio of magnitude of acceleration while moving up to that while moving down is:

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G1 Physics · Accepted Answer

While moving up, gravity and friction both act down the plane: a_up = g(sinθ + μcosθ)=g(0.6+0.25×0.8)=0.8g. While moving down, friction acts up the plane: a_down = g(sinθ-μcosθ)=g(0.6-0.2)=0.4g. Ratio = 0.8/0.4 = 2.