Question

A block of metal weighing 2 kg is resting on a frictionless plane. It is struck by a jet releasing water at a rate of 1 kg/s and at a speed of 5 m/s. The initial acceleration of the block will be

Answer 1

Explanation:

♦The final velocity of mass of water after hitting the metal block is zero.

So the average change in momentum per sec = initial momentum

=mass×initial velocity of water

=1kg×5m/s=5kgm/s

As this change in momentum occurs during 1 sec. We may say that the force exerted on the 2kg metal block is

F=change in momentum

time=5kgm/s1s=5N

Hence by Newton's law initial acceleration of the block of mass

m=2kg

is given

Answer 2

Answer :-

F = v dm/dt

= 5 x 1

= 5N

acceleration= a = F/m

= 5/2

= 2.5 ms⁻²