Question

A body of mass 400 kg is suspended at a lower end of a light vertical chain and is being pulled up vertically. Initially the body is at rest and the pull on the chain is 6000 g (g is 9.8 m/s^2) The pull gets smaller uniformly at the rate of 360g N per each meter through which the body is raised. What is the velocity of the body when it has been raised 10m?

Answer 1

Answer:31.62 m/s

Explanation:

Given

mass of body $m=400 kg$

Pull on chain is $F_1=6000g N=60 kN$

Pull get smaller at the rate of $F_2=360g N/m$

Net Upward Force $F=6000 g-360 g\times 10=24 kN$

net acceleration $a=\frac{F}{m}$

$a=\frac{24\times 1000}{m}$

$a=\frac{24000}{400}$

$a=60 m/s^2$

but g is acting downward

$a_{net}=a-g=60-10=50 m/s^2$

using $v^2-u^2=2 as$

here initial velocity is zero

$v^2=2\times 50\times 10$

$v=31.62 m/s$