Question

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

• A. $5$
• B. $1.5$
• C. $2.5$
• D. $25$

Answer 1

Answer: (C)

$2.5$

The mass of bullet is $20g$ or $0.02kg$.

The momentum of the bullet is $10kg\cdot m/s$

The kinetic energy of a body in terms of its momentum is given as:

$KE=\frac{p^2}{2m}$

$KE=\frac{10\times 10}{2\times 0.02}$

$2500J=2.5kJ$

The correct answer is c) $2.5$