If a bullet of mass 5gm moving with velocity `100m//sec`, penertates the wooden block upto 6cm. Then the average force imposed by the bullet on the block is

Options

A. 8300 N
B. 417 N
C. 830 N
D. Zero

Answer

B

Explanation

` u = 100 m//s : m = 0.005 kg : v = 0`
Retardation ` = a = (u^(2))/(2s) = ((100)^(2))/(2xx0.06) = (10^(6))/(12)`
Force (F) ` = ma = (5 xx 10^(-3) xx 10^(6))/(12) = (5000)/(12) = 417N`
Aliter :
Change in K.E = work done
`rArr (1)/(2)mv^(2) - (1)/(2)mu^(2) = FS`
`rArr F = -[((1)/(2)xx 0.005xx(100)^(2))/(0.06)] = - 417 N`
- ve sing represent retarding force.