When a hammer strikes a nail, the nail

The nail will exert a force of equal strength in the opposite direction on the first object.

Explanation:

"According to Newton's third law of motion, when a hammer strikes and exerts force on a nail, the nail exerts a force of equal strength in the opposite direction on the first object."

Basically, if you push someone, they will fall over right?

Still, you will feel the force as you push them over, and you might stumble back while they are pinwheeling and falling into a pool.

That force is that torque when the person's weight is also pushing back at you while your force is pushing at them.