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Home  >>  JEEMAIN and AIPMT  >>  Physics  >>  Class11  >>  Work, Power and Energy
0 votes

A bullet fired from rifle. The ratio of kinetic energy of rifle to that of bullet after firing is

a) more than one b) less than one c) equal to one d) zero
Can you answer this question?
 
 

1 Answer

0 votes
Let,
$M$ -mass of life
$v$- velocity of rifle
$m$ -mass of bullet
$u$ -velocity of bullet
$Mv=mu$
$\large\frac{K_r}{K_b}=\frac{\Large\frac{1}{2}Mv^2}{\Large\frac{1}{2}mv^2}$
$\large\frac{(Mv)^2}{(Mu)^2} $$\times \large \frac{m}{M}=\large\frac{m}{M}$
Since $m$ < $M$
$K_b \;>\;K_r$
Therefore $\large\frac{Kinetic\;energy\;of\;rifle}{Kinetic\;energy\;of\;bullet} \;< \;1$
Hence b is the correct answer. 

 

answered Jul 19, 2013 by meena.p
edited Feb 10, 2014 by meena.p
 

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