Physics help!?

Question

I'm doing a physics project for my final. I am trying to find the force of how hard I hit a tennis ball. I dropped the ball and let it bouce back up then hit it at the top so the Velocity is 0. I found time and distance but I don't know how I should find the Force. It's driving me crazy and I have to finish this thing by Moday so I'm starting to freak out. Can anyone help me??!

Answer 1

Hi. Don't panic. In order for a force to do work, it must be applied through a distance. without realizing it, you have tacitly assumed that a force can stop a moving ball instantaneously. What complicates the matter even more is that gravity is working at the same time. Allow me to recommend that you change your problem to a ball moving on a horizontal surface, coming in contact with a tennis racket. Measure the mass of the ball, make an assumption of how much force you can exert with the racket. The moving ball has a certain amount of kinetic energy by virtue of its motion, mv^2. The force you are able to exert, working through a distance is able to stop the moving ball. Energy equals force times distance. That would be a decelerating force.