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5.Work, Energy, Power and Collision
hard
When kinetic energy of a body becomes $36$ times of its original value, the percentage increase in the momentum of the body will be :
A
$500 \%$
B
$600 \%$
C
$6 \%$
D
$60 \%$
(JEE MAIN-2024)
Solution
$\text { Kinetic energy }(\mathrm{K})=\frac{\mathrm{P}^2}{2 \mathrm{~m}}$
$\Rightarrow \mathrm{P}=\sqrt{2 \mathrm{mK}}$
$\text { If } \mathrm{K}_{\mathrm{f}}=36 \mathrm{~K}_{\mathrm{i}}$
$\text { So, } \mathrm{P}_{\mathrm{f}}=6 \mathrm{P}_{\mathrm{i}}$
$\% \text { increase in momentum }=\frac{P_f-P_i}{P_i} \times 100 \%$
$=\frac{6 \mathrm{P}_{\mathrm{i}}-\mathrm{P}_{\mathrm{i}}}{\mathrm{P}_{\mathrm{i}}} \times 100 \%$
$=500 \%$
Standard 11
Physics