Question.
A hammer of mass 500 g, moving at 50 ms–1, strikes a nail. The nail stops the hammer
in a very short time of 0.01 s. What is the force of the nail on the hammer ?
Solution:
The force of nail on the hammer
$F=\frac{\text { Change in momentum of hammer }}{\text { Time }}$
$\mathrm{F}=\frac{\mathrm{m}(\mathrm{v}-\mathrm{u})}{\mathrm{t}}=\frac{0.5(0-50)}{0.01}=-2500 \mathrm{~N}$
Negative sign denotes that the force of nail on the hammer is acting in the direction opposite
to that of motion of hammer.
The force of nail on the hammer
$F=\frac{\text { Change in momentum of hammer }}{\text { Time }}$
$\mathrm{F}=\frac{\mathrm{m}(\mathrm{v}-\mathrm{u})}{\mathrm{t}}=\frac{0.5(0-50)}{0.01}=-2500 \mathrm{~N}$
Negative sign denotes that the force of nail on the hammer is acting in the direction opposite
to that of motion of hammer.