Q. A bullet fired from a gun with a velocity of $10^{4}\ ms^{- 1}$ goes through a bag full of straw. If the bullet loses half of its kinetic energy in the bag, its velocity when it comes out of the bag will be
A) $7071.06\ ms^{- 1}$
B) $707\ ms^{- 1}$
C) $70.71\ ms^{- 1}$
D) $707.06\ ms^{- 1}$
Explanation
(a) KE left, $\frac{1}{2}mv^{2} = \frac{1}{2}\ \left( \frac{1}{2}mu^{2} \right)$
$\therefore$ velocity left, $v = \frac{u}{\sqrt{2}} = \frac{10^{4}}{\sqrt{2}} = 7071.06\ ms^{- 1}$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.