Question

A hammer of mass 500 g, moving at $50m{s}^{-1}$, strikes a nail. The nail stops the hammer in a very short time of 0.01s. What is the force of the nail on the hammer?

• A. 2500 N
• B. -2500 N
• C. 1500 N
• D. -1500 N

Answer 1

The correct option is B -2500 N

The force of nail on the hammer
$F=\frac{\text{Change in momentum of hammer}}{Time}$
$F=\frac{m(v-u)}{t}=\frac{0.5(0-50)}{0.01}=-2500N$
Negative sign denotes that the force of nail on the hammer is acting in the direction opposite to that of motion of hammer.