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!

1 mark question on application of components and workdone(gravitanal potential energy

  1. Apr 6, 2012 #1
    1. The problem statement, all variables and given/known data

    http://www.xtremepapers.com/CIE/International A And AS Level/9702 - Physics/9702_w10_qp_12.pdf

    question 14



    2. Relevant equations
    mgh=gpE
    fxd=workdone



    3. The attempt at a solution

    I HAVE NO IDEA WHY MY ANSWER IS WRONG!! AND THIS IS GETTING ME so WORRIED ABOUT MY CONCEPTUAL UNDERSTANDING!
    I found the component down the surface which was 100N, I added 150N to this(as he has to overcome the friction) so now i just use Fxd=250x1.5=375j. But the actual answer is 750j HOW COME??
     
  2. jcsd
  3. Apr 6, 2012 #2

    ehild

    User Avatar
    Homework Helper
    Gold Member

    Re: 1 mark question on application of components and workdone(gravitanal potential en

    The 250 N force acts along the length of the slope. 1.5 m is the height.

    ehild
     
  4. Apr 6, 2012 #3
    Re: 1 mark question on application of components and workdone(gravitanal potential en

    2 works done here.
    1. Overheating the surface, friction.
    2. Increases the PE,

    Workout separately and added them.
     
  5. Apr 6, 2012 #4
    Re: 1 mark question on application of components and workdone(gravitanal potential en

    ISn't the energy we are evaluating mgh?(which is the same as Fxd). SO whenever we use gravitational potential energy, shouldnt we use the height and not the slope!
     
  6. Apr 6, 2012 #5
    Re: 1 mark question on application of components and workdone(gravitanal potential en

    Since you have found the component down the surface then use the component of length of the surface.

    Actually work done= FxdxCosθ
     
  7. Apr 6, 2012 #6

    ehild

    User Avatar
    Homework Helper
    Gold Member

    Re: 1 mark question on application of components and workdone(gravitanal potential en

    The question reads: "What is the work done by the person?".It is not equal to the gravitational potential energy.

    ehild
     
  8. Apr 6, 2012 #7
    Re: 1 mark question on application of components and workdone(gravitanal potential en

    the persion pushes along the slope. If you know the height you can calculate the sloping distance.
    I also got the total pushing force to be 250N
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: 1 mark question on application of components and workdone(gravitanal potential energy
Loading...