Question

A bullet of mass $0.02$ kg moving with a velocity of $30{ms}^{-1}$ is brought to rest by a wooden plank. Calculate the work done on the bullet before it comes to rest.

• A. $-9$
• B. $9$
• C. $18$
• D. $-18$

Answer 1

The correct option is A $-9$

Initial energy $=\frac{1}{2}\times 0.02\times 900$

$=9J$

Final Energy $=0J$

Work is done against the motion of bullet

Final Energy - Initial Energy$=$ Work done

$-9J=$work done