Question

A 250 g block slides on a rough horizontal table. Find the work done by the frictional force in bringing the block to rest if it is initially moving at a speed of 40 cm/s. If the friction coefficient between the table and the block is 0.1, how for does the block move before coming to rest?

Answer 1

Given, $m=250gm=0.250kg$

$u=40cm/sec$

$=0.4m/sec,\mu =0.1,v=0$

Here, $\mu R=ma$

(where a is deceleration)

$a=\left(\frac{\mu R}{m}\right)=\left(\frac{\mu mg}{m}\right)=\mu g$

$=0.1\times 9.8=0.98m/s^2$

$s=\frac{v^2-u^2}{2a}=0.082m$

$=8.2cm$