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Homework Help: Desperatly need help, have no idea where to start

  1. Jan 2, 2008 #1
    1. The problem statement, all variables and given/known data
    A block of 10kg is on a plane elevated 35 degrees. if it starts at rest at the bottom of the 10m ramp, and the coefficient of kinetic friction is .15, what is the force need to push the block up the entire ramp in 8.0s.

    2. Relevant equations

    3. The attempt at a solution

    i know force of friction goes against the motion, but honestly thats it, i need advice at where i should start (my teacher is horrible, makes mistakes on his own problems his 1st year teaching)
  2. jcsd
  3. Jan 2, 2008 #2

    Doc Al

    User Avatar

    Staff: Mentor

    Some hints:
    (1) What acceleration is required? (Use kinematics to figure it out from the distance and time.)
    (2) What net force is required? (Newton's 2nd law.)
    (3) What are all the forces acting on the block parallel to the plane? The unknown applied force is one of them: Write an equation for the sum of the forces and solve for that needed force.
  4. Jan 2, 2008 #3
    use components, seperate the x and the y axis .. let me see if i can try to actually figure it out
  5. Jan 2, 2008 #4
    thanks for the hints and help, i figured out the accleration, but to find the force would i calculate the net force and then subtract the Ff from the net force and find the answer that way or am i approaching it wrong?
  6. Jan 2, 2008 #5
    if you can figure it out can you post the steps, i have problems like this as well and if i see your method i can learn off that.
  7. Jan 2, 2008 #6
    besides the y component in gravity and normal force if i tilit my axis due to the ramp, what other purpose do i use components for
  8. Jan 2, 2008 #7
    What is the relationship between Normal force and Friction?

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