Question

the average force necessary to stop a hammer with momentum p Ns in 0.5s is

Answer 1

Force = change in momentum / time
here, initial momentum = p
if hammer comes to rest, final momentum = 0

change in momentum = p - 0 = p
time = 0.5s
Average force = p/0.5 = 2p N
Average force is 2p Newton.

Answer 2

Given data:  

The hammer to be stopped with initial momentum as p given.

The force to be calculated is in accordance with the Second laws of motion given by Newton.  

The force is the rate of change of momentum with time.  

Initial momentum = p  

Final momentum = 0, (as the hammer stops)

Therefore, force $= \frac{\text {change in momentum}}{\text {time}}$

$\begin{array}{l}{F=p-\frac{0}{t}} \\ {F=\frac{p}{0.5}} \\ {\text { Average force, } F=2 p N}\end{array}$.