Question

A body slides down a rough inclined plane of inclination $\theta$ with constant velocity $v$. If it is projected up the plane with velocity $2v$, then it moves up the plane with

• A. constant velocity
• B. retardation g sin $\theta$
• C. retardation 2gsin $\theta$
• D. acceleration g sin $\theta$

Answer 1

Answer: (C)

retardation 2gsin $\theta$

It is sliding down with constant velocity v, friction $f=mgsin\theta$

When ball is projected upward $f$ and $mgsin\theta$ will act in same direction (i.e backward direction)

So retardation of body is $\frac{f+mgsin\theta }{m}=2gsin\theta$