Question

A bullet of mass $10\text{g}$ leaves a riffle at an initial velocity of $1000\text{m/s}$ and strikes the earth at the same level with a velocity of $500\text{m/s}$. The work done in overcoming the resistance of air will be:

• A. 500 J
• B. 5000 J
• C. 3750 J
• D. 475 J

Answer 1

The correct option is C 3750 J

Loss of kinetic energy of bullet
= The work done in over coming air resistance.
$=\frac{1}{2}\times \frac{10}{1000}({1000}^2-{500}^2)$
$=\frac{1}{2}\times \frac{1}{100}\times 1500\times 500=3750\text{J}$