The retardation 'a' of the bullet (assumed constant) is given by

a=-u^2/2s=-90*90/2*0.6ms^-2=-6750ms^-2

Hello Student,

The wooden block provides a constant resistive force and hence the bullet deccelerates at a constant rate, let it be a .

Since the bullet stops after 60cm there fore final velocity is 0

1. v² - u² = 2as

or a = -u²/2a = 90²/2*0.6 = -6750m/s²

2.Therefore the retarding force will be

Mass of bullet * decceleration = 0.04kg * -6750m/s² = -270N

Hello,

This is a simple question and can be solved with Newton's Second Law.

According to it, F=ma.

here m is mass of bullet. (0.04kg)

a is acceleration of bullet ( can be calculated using speed and distance)

we know, v^2-u^2=2as

here, v=0 m/s , u=90m/s  and   s is 0.6m

therefore, a= - 6750m/s^2

Hence we can find resistive force (F) = 0.04 x ( - 6750) = - 270N.

Here negative sign indicates that the force applied by the block is in opposite direction to the velocity of the bullet.

Hope this helps.

Thanks