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!

Homework Help: 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


    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.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook