Question

A block weighing $10N$ travels down a smooth curved track $AB$ joined to a rough horizontal surface (figure).The rough surface has a friction coefficient of $0.20$ with the block. If the block starts slipping on the track from a point $1.0m$ above the horizontal surface, the distance it will move on the rough surface is :

• A. $5.0m$
• B. $10.0m$
• C. $15.0m$
• D. $20.0m$

Answer 1

Answer: (A)

$5.0m$

Let the velocity at point B be $V$.

By conservation of energy, $mgh=\frac{1}{2}m{v}^2\Rightarrow v=\sqrt{2gh}$.

Now deceleration due to friction is $a=\mu g=0.2g$.

So stopping distance, $s=\frac{v^2}{2a}=2gh/0.4g=5h=5\times 1=5m$