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Find average force during contact when ball hits wall.

  1. Sep 3, 2009 #1
    A tennis ball has a mass of 0.057 kg. A professional tennis player hits the ball hard enough to give it a speed of 44 m/s (about 99 miles per hour.) The ball moves toward the left, hits a wall and bounces straight back to the right with almost the same speed (44 m/s). As indicated in the diagram below, high-speed photography shows that the ball is crushed about 2 cm at the instant when its speed is momentarily zero, before rebounding.

    What is the magnitude of the average force exerted by the wall on the ball during contact?
  2. jcsd
  3. Sep 3, 2009 #2
    The instant the ball touches the wall it starts accelerating for 2cm. After you figure out what too do with that you just use the impulse equation.

    You're also suppossed to post equations needed + work.
  4. Sep 3, 2009 #3


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    Homework Helper

    Welcome to PF.
    Before you seek our help, you have show your attempt.
    What are the relevant equations you can use to solve this problem?
  5. Sep 3, 2009 #4
    i did attempt the problem. spend half hour on it. I just didn't copy everything i wrote on paper. Thought it would be too messy on forum and no one would want to read all that junk.

    The problem with you guys is that you assume the worst of people.
  6. Sep 3, 2009 #5


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    Homework Helper

    Writing the relevant equations and substituting the given values is not a messy work.
    Before extending our help, we must, how much you know about the problem.

    Can you say why the ball stops before it rebounds?
  7. Sep 3, 2009 #6
    idk. maybe because it hit the wall.

    but i do know: this forum suck ***.
  8. Sep 3, 2009 #7
    That's very unfair,there are people on this forum who regularly and freely give their time and advice, but in order to help you best it is necessary to know what you have already tried so that you can be guided in the right direction.So what if you think your previous attempts have been what you call "junk",I don't think many people here would be too concerned about that.How about trying again and please don't worry about presenting what you have tried, no matter how little or wrong you think this may be.
    Last edited: Sep 3, 2009
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