800 Newtons
Step-by-step explanation
The average force is the force exerted by a body moving at a defined rate of speed (velocity) for a defined period of time.
the average force is given by:
and
Step 1
a) Let
now, replace
the negative sign indicates the force is in the opposite way ( the force is exerted by the nail to the hammer), so the force is opposite to the direction of the movement
so, the answer is
800 Newtons
I hope this helps you