1. Not finding help here? Sign up for a free 30min 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!

Overcoming friction and then some.

  1. Nov 23, 2007 #1
    [SOLVED] Overcoming friction and then some.

    Can anybody help me figure if I have this right?

    You push a loaded wheelbarrow of mass 130 kg, exerting a horizontal force of 120 N as you do so. As the wheelbarrow moves, the frictional force acting on it is 85 N.
    (a) If you begin from rest, how far do you push the wheelbarrow before reaching a moderate walking speed of 1.3 m/s?
    (b) Over this distance, how much work do you do on the wheelbarrow?
    (c) How much work does the frictional force do on the wheelbarrow?
    (d) What is the final kinetic energy of the wheelbarrow?


    a) a = 120/130 = .9m/s^2
    1.3^2 = 2(.9)(x)
    1.69/1.8 = .94 m

    b) W = 120(.94) = 112.8J

    c) W = 85(.94)(-1) = -79.9J

    d) K = 1/2(130)(1.3^2) = 109.85J
     
  2. jcsd
  3. Nov 23, 2007 #2

    PhanthomJay

    User Avatar
    Science Advisor
    Homework Helper
    Gold Member

    In calculating the acceleration, you must use the NET force acting on the wheelbarrow, not just the applied force.
     
  4. Nov 23, 2007 #3
    But isn't the NET force equal to the force (120) since that is the only force without a nonzero x-component?

    or am I wrong?
     
  5. Nov 23, 2007 #4

    PhanthomJay

    User Avatar
    Science Advisor
    Homework Helper
    Gold Member

    What about the given friction force which opposes the motion in the horizontal direction?
     
  6. Nov 24, 2007 #5
    You are right, thank you.

    Will this cover it? (NET force = applied force - friction force)
     
  7. Nov 24, 2007 #6

    PhanthomJay

    User Avatar
    Science Advisor
    Homework Helper
    Gold Member

    yes, that is correct, in the x direction.
     
  8. Nov 24, 2007 #7
    Thank you for your help
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?



Similar Discussions: Overcoming friction and then some.
  1. Overcoming Friction (Replies: 28)

  2. Overcoming Friction (Replies: 1)

  3. Overcoming friction (Replies: 1)

Loading...