your friend says that the heavyweight champion of the world cannot exert a force of 50N on a piece of tissue paper with his best punch. the tissue paper is held in midair- no wall, no tricks. you?

Answer 1

Is "you" the question?

Is the tissue really held?

The claim is probably true when you consider the mass of a tissue (about 0.001 kg) and the maximum acceleration a fist can apply, about 50 m/s^2.

Remember that F = ma