Question

A bullet of mass $50g$ is moving with a velocity of $500m{s}^{-1}$. it penetrates $10cm$ into a still target and comes to rest.Calculate
(a) The kinetic energy possessed by the bullet,
(b) The average retarding force offered by the target.

Answer 1

Now,

$v^2=u^2+2as0=(500{)}^2+2(a)\frac{\left(10\right)}{100}\Rightarrow a=-1250000m/s$

Average retarding force $=\frac{50}{1000}\times \left(1250000\right)$

$\Rightarrow F_{av}=62500NK.E=\frac{1}{2}m{v}^2=\frac{1}{2}\times \frac{50}{1000}\times (500{)}^{2}K.E=\frac{25000}{4}=6250joule$