The momentum of a bullet of mass 20 g fired from a gun is 10 kg m/s. The kinetic energy of this bullet in kJ will be:

1. 25
2. 2.5
3. 0.25
4. 5

Mass of the fired bullet $m=20\ gm=\frac{20}{1000}=0.02\ kg$

The momentum of the bullet $P=10\ kg-m/s$

Therefore, the velocity of the bullet $v=\frac{P}{v}$

$=\frac{10}{0.02}\ m/s$

$=500\ m/s$

Therefore, kinetic energy $K=\frac{1}{2}\times0.2\times500^2$

$=25000\ J$

$=25\ KJ$

Therefore, option a). is correct.

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Updated on: 10-Oct-2022

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