According to Newton's Third Law, if a hammer puts a force of 200 N on a nail, how much force does the nail put back on the hammer?

a
200 N
b
-200 N
c
50 N
d
150 N

According to Newton's Third Law, the force exerted by the nail on the hammer will be equal in magnitude but opposite in direction to the force exerted by the hammer on the nail. Therefore, the force exerted by the nail back on the hammer would also be 200 N, but in the opposite direction.

So the correct answer is b) -200 N.