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A body of mass 'm' is launched up a rough inclined plane making an angle of 30° with the horizontal. The coefficient of friction between the body and the plane is √x/5 if the time of ascent is half of the time of descent. The value of x is _____.

1. 1
2. 2
3. 3
4. 4

Correct answer: 3

Solution

The relationship between the time of ascent and descent indicates that the forces acting on the body, including friction, must balance in such a way that the acceleration during ascent is half that of descent. Given the angle and the coefficient of friction, solving the equations of motion leads to the conclusion that x must equal 3 to satisfy these conditions.

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