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 the average retarding force offered by the target.

• A. $0N$
• B. $625N$
• C. $62500N$
• D. $6.25N$

Answer 1

The correct option is C $62500N$

Kinetic Energy, $K.E=0.5\ast m\ast v^2$

Given, m = 50 gram = 50/1000 = 1/20 Kg and Final velocity = 0 m/sec; initial velocity= 500 m/sec

$K.E=\frac{1}{2\times 20}(500\ast 500)Joule$

$K.E=6250J$

$K.E=F\ast S$ (By work energy theorem)

Given S = 10 cm = 0.1 m.

$6250=F\ast 0.1$

$F=6250\ast 10=62500N$

Hence there is an average retarding force of $62500N$.