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!

Calculating work done on a truck by friction when a truck is pushing a car

  1. Sep 14, 2008 #1
    1. The problem statement, all variables and given/known data

    A truck pushes a car by exerting a horizontal force of 500 N on it. A frictional force of 300N opposes the cars motion as it moves 4m. Calculate the work done on the truck.


    2. Relevant equations

    work = force x distance


    3. The attempt at a solution

    work done = 300N x 4 m = 1200J work right?
     
  2. jcsd
  3. Sep 15, 2008 #2

    alphysicist

    User Avatar
    Homework Helper

    For constant forces, the work would be:

    [tex]
    W=F d\cos\theta
    [/tex]

    where [itex]\theta[/itex] is the angle between the force diretion and the displacement direction.


    No, I believe that would be the magnitude of the work done by friction. Remember that if we want to calculate the work done on the truck, you have to use the forces that act on the truck.
     
  4. Nov 20, 2008 #3
    My contribution: since the work done by resulting force on the body is the path integral along the path and this is a scalar (inner product from two vectors), is straightforward that the work of resulting force shall be the algebraic sum of work from each force acting on the considered body; in this way:

    W = 500N x4 m - 300N x 4m = 800J

    Danpos.
     
  5. Nov 20, 2008 #4
    Not correct: the 300N force is NOT the force acting on the truck.
     
  6. Nov 20, 2008 #5
    The title of your post asks a different question that your post itself: which one is the actual question? And, don't you have more info?
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?



Similar Discussions: Calculating work done on a truck by friction when a truck is pushing a car
  1. A car and a truck (Replies: 4)

  2. Car pushing on truck (Replies: 1)

Loading...