t = time of contact of hammer with the nail = 0.4 sec
I = impulse exerted by the hammer on the nail = 32 N s
F = force applied by the hammer on the nail
we know that , impulse is given as
I = F t where I = impulse , F = force , t = time
hence the impulse of hammer on nail is given as
I = F t
inserting the values
32 Ns = F (0.4 sec)
F = 32/0.4
F = 80 N
hence the force exerted by the hammer comes out to be 80 N