Question

A block of mass 30.0 kg is being brought down by a chain. If the block acquires a speed of 40.0 cm/s in dropping down 2.00 m, find the work done by the chain during the process.

Answer 1

$Givenm=30kg,$

$v=40cm/sec$

$=0.4m/sec$

$S=2m$

From the free body diagram, the force given by the chain is

$F=(ma-mg)$

$=m(a-g)$

[Where a=acceleration of the block]

$a=\frac{v^2-u^2}{2S}$

$=\frac{16}{-4}=0.04m/se{c}^2$

So, work done $=W=FScos\theta$

$=m(a-g)Scos{0}^{\circ }$

$=30(0.04-9.8)\times 2$

$=-30\times \left(9.76\right)\times 2$

$=-585.6=-586J$

So, $W=-586J$