Mass and free fall question

  1. A ball of mass .5 kg is dropped from a height of 5 m. What is the greatest velocity it will have just before hitting the ground?

    vf squared = vi squared + 2ad

    vf squared = 0 squared + 2(9.8)(5)

    vf = 9.8 m/s

    So the greatest velocity is 9.8 m/s, right?

    I am still very confuzzled and I think this is the right answer because where did the mass go? Or it doesn't even matter? Can someone verify?

    Thanks!
     
  2. jcsd
  3. rl.bhat

    rl.bhat 4,435
    Homework Helper

    Yes. Mass does not matter in the free fall under gravity. All the body get accelerated equally.
     
  4. Dick

    Dick 25,887
    Science Advisor
    Homework Helper

    Welcome to the forums! No, mass doesn't matter. The acceleration downwards is g, independent of mass, ask Galileo. It's a purely kinematical problem.
     
  5. Thanks! So is my answer correct?
     
  6. Dick

    Dick 25,887
    Science Advisor
    Homework Helper

    Approximately, yes. I would round the answer to 9.9m/sec. But that's a detail.
     
  7. Sweet! Thanks!
     
  8. I don't know why the question had mass in it. Trick question or something haha.
     
  9. Dick

    Dick 25,887
    Science Advisor
    Homework Helper

    In real world problems YOU have to figure out what's important and what isn't. It's just practice.
     
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