Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Work and net work question - Thanks!

  1. Nov 21, 2011 #1
    1. The problem statement, all variables and given/known data

    Here is the question:

    "A ball moves through the air, and experiences a force of air resistance, in addition to the force of gravity. While it moves, its total mechanical energy decreases by 15J, and its gravitational potential evergy decreases by 25J"

    A: What is the net work done on this ball by all the forces acting on it?

    B: What is the work done on the ball by the force of air resistance.

    C: What is the work done on the ball by the force of Gravity?

    2. Relevant equations

    3. The attempt at a solution

    I'm not sure which formulas to use here... Can anyone help me out?
  2. jcsd
  3. Nov 21, 2011 #2


    User Avatar

    Staff: Mentor

    What are the units of work? If a mass' vertical position is changed, what happens to its gravitational potential energy? What is the equation for gravitational PE in terms of the mass and the change in height?

    What is the question referring to when it uses the term "mechanical energy"? What is the more common/scientific term for this?
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook