1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
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
    2017 Award

    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?
Draft saved Draft deleted