Question

A small block B is placed on another block A of mass 5 kg and length 20 cm. Initially the block B is near the right end of block A Figure. A constant horizontal force of 10 N is applied to the block A. All the surfaces are assumed frictionless. Find the time elapsed before the block B separates from A.

Answer 1

Given, m = 5 kg block a

ma = 10 N

$\Rightarrow$ a $=\frac{10}{5}=2m/s^2$

As there is no friction between A and B when the block A moves, block B remains at rest in its position.

Initial velocity of a , u = 0

Distance to cover by B to separate out,

S = 0.2 m

Acceleration , a = 2 $m/s^2$

We know, S = $ut+\frac{1}{2}a{t}^2$

$\Rightarrow 0.2=0+\frac{1}{2}\times 2t^2$

$\Rightarrow t^2=0.2$

$\Rightarrow t=0.44sec\approx 0.45sec$