Question

A bullet of mass 10 gm moving with velocity of 100 m/sec hits a wooden log and penetrates it upto thickness of 5 cm. The resistance force of the log is

• A. 200 N
• B. 500 N
• C. 1000 N
• D. 600 N

Answer 1

The correct option is C 1000 N

The retarding force applied by the block will stop the bullet completely.
Hence, the loss of kinetic energy $(m\times v^2)/2$ will be equal to the work done by that retarding force .
Therefore,
$W=F\times s=\left(m{v}^2\right)/2$
on solving it gives , $F=1000$ N