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

B Energy Confusion (Conservation of Energy?)

  1. Jun 6, 2018 #1
    Anyone know if the following statement is true (and why)?

    "Getting to higher ground would increase his gravitational potential energy, decreasing the effects of non-conservative forces, which would allow him to move easier."

    CLARIFICATION: "move easier" refers to a lack of friction and not the slight increase in gravitational force. Do with that what you will.
    Last edited: Jun 6, 2018
  2. jcsd
  3. Jun 6, 2018 #2


    User Avatar
    Science Advisor
    Gold Member

    Hmmm. I can't think what would "allow him to move easier" as g on higher ground is almost undetectably different from g at sea level.
    Where did you find that statement?
  4. Jun 6, 2018 #3


    Staff: Mentor

    This part is true

    This part seems weird, like it was written by a drunk physicist.
  5. Jun 16, 2018 #4


    User Avatar
    Science Advisor
    Homework Helper
    Gold Member

    Friction actually makes it easier to move. If there was no friction driving and walking would be impossible.
  6. Jun 18, 2018 #5
    Do you mean friction or air-resistance? The air resistance is dependent on the density of air, which does decrease with increasing height. However, in practice a person would have to account for the fact that there would be less oxygen present due to the lower pressure.

    The frictional force is, to a first approximation, usually given by f=μN, where μ is the coefficient of friction and N is the normal force.
    Since N in many cases is opposing the gravitational force acting on the object, a change in g could result in a change of friction with height, but as @sophiecentaur noted, the rate at which g varies with height is small (the difference between g at sea level and a height corresponding to the top of Mount Everest can be calculated to be about 0.03 ms-2, even at the ISS, g is about 0.9 times that at sea-level), so in practice there would be little variation in friction.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook

Have something to add?