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Work Problem: Up a ramp

  1. Oct 14, 2009 #1
    1. The problem statement, all variables and given/known data

    Moving a 150kg fridge a 12m ramp with a rise of 2.4m. the mover pulls the ridge up with a constant force of 710 N. the acceleration due to gravity is 9.8 m/s^2

    2. Relevant equations

    W=Fs
    F=ma

    3. The attempt at a solution

    I found out the angle of the ramp was by doing arcsin(2.4/12)= 11.536959 degrees
    So im trying to figure out which forces to split into two components using this angle.

    which then i will plug into w=Fs

    i set the x and y direction as the direction of the ramp so I split the force of gravity into two components.

    i took 710N- Fg)x= Fnet
    so i did 710-mgsin(11.536959)=416 N
    then i multiplied that number by 12
    and got 4992

    is this correct if not can you lead me in the right direction
     
  2. jcsd
  3. Oct 14, 2009 #2
    If you are trying to find the work done, I think it's right if I understand the question correctly.
     
  4. Oct 14, 2009 #3
    I got that answer wrong is there a component im forgetting?
     
  5. Oct 14, 2009 #4
    There is also a potential energy. which is work (potential)=mgh=150*9.8*2.4=3528
    I think work=Kinetic Energy+Potential Energy=3528+4992=8520
     
  6. Oct 14, 2009 #5
    hmmm but the question asks... how much work does HE perform.
     
  7. Oct 14, 2009 #6
    What is HE? Sorry, not a native speaker
     
  8. Oct 14, 2009 #7
    by He i mean..... how much work does the person who pulls the fridge up the ramp do?
     
  9. Oct 14, 2009 #8
    Yeah, he does work by performing kinetic energy to the fridge as well as pulling the fridge up 2.4 meters (vertically).
     
  10. Oct 14, 2009 #9
    so does mean i should add the PE to 4992N?
     
  11. Oct 14, 2009 #10
    I think so. If I am wrong, then I am sorry... I am interested in finding out the answer.
     
  12. Oct 14, 2009 #11
    i only have two more tries left for this problem, thankyou for your help though. i think im going to my study TA tomorrow.
     
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