Question

A block weighing 10 N 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 1.0 m above the horizontal surface, how far will it move on the rough surface?

• A. 0 m
• B. 20 m
• C. 10 m
• D. 5 m

Answer 1

The correct option is D

5 m

$W_{net}=\Delta K.E$.

We Know $\Delta K.E=0$

$\therefore W_g+W_f=0$

$W_g=mgh,W_f=-\mu Nx$ {x is the distance it moves on the horizontal surface}

$\Rightarrow W_g+W_f=mgh-\mu Nx=0$

$\Rightarrow mgh-\mu mgx=0$(as N = mg)

$\Rightarrow mgh=\mu mgx$

$\Rightarrow 10\times 1=0.2\left(10\right)x$

$\Rightarrow x=5m$