Question

A bullet of mass $10gm$ hits a fixed target and penetrates through $8cm$ in it before coming to rest. If the average resistance offered by the target is $100N$, the velocity with which the bullet hits the target is,

• A. $20m/s$
• B. $25m/s$
• C. $40m/s$
• D. $50m/s$

Answer 1

The correct option is C $40m/s$

Given ,

Distance, $s=8cm=0.08m$

$u=?$

$v=0$

Force, $F=-100N$

Mass $=10gm=0.01kg$

By 2nd law of motion

$F=ma$

$-100=0.01\times a$

$\frac{-100}{0.01}=a$

$a=-10000m/s^2$

By equation,

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

$0-u^2=2\times -10000\times 0.08$

$-u^2=-1600$

$u=40m/s$