When a boxer punches a tissue, it is like punching a cushion or a pillow. The time that the hit takes is much grater than if they were to hit something solid. In addition, the change in velocity of the boxer's arm would be much greater when they hit a punching bag. In this equation, the greater the time, the less force that is needed.
A. A fast moving stream. Water has erode Earth for thousands of years. This was what caused the Grand Canyon. A faster ,owing stream would cause a faster erosion due to the speed and strength of the water itself.
