Question

A bullet of mass 30 gram strikes target with velocity 90 metre per second is brought to rest after penetrating 15 cm into it calculate work done​

Answer 1

Answer:

0.135j

Explanation:

first convert each term in SI unit. Than calculate acceleration by the 3rd formula of kynamatics .

Than calculate force and multiply with distance.

Answer 2

Answer:

$\mathsf{W=\underline{\underline{-121.5\ J}}}$

Explanation:

Given:

$\leadsto\ \mathsf{m=30\ g=0.03\ kg}\\\\\leadsto\ \mathsf{u=90\ ms^{-1}}\\\\\leadsto\ \mathsf{v=0\ ms^{-1}}\\\\\leadsto\ \mathsf{s=15\ cm=0.15\ m}$

By work - energy theorem,

$\leadsto\ \textsf{Net work done = Change in kinetic energy}\\\\\\\leadsto\ \mathsf{W=\dfrac{1}{2}mv^2-\dfrac{1}{2}mu^2}\\\\\\\leadsto\ \mathsf{W=\dfrac{1}{2}m(v^2-u^2)}\\\\\\\leadsto\ \mathsf{W=\dfrac{1}{2}\times0.03(0^2-90^2)}\\\\\\\leadsto\ \mathsf{W=-\dfrac{1}{2}\times0.03\times 8100}\\\\\\\leadsto\ \mathsf{W=\underline{\underline{-121.5\ J}}}$