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!

Pushing a lawnmower. picture included

  1. Sep 21, 2008 #1
    http://tinypic.com/view.php?pic=1zyvjut&s=4

    Consider a lawnmower of weight w which can slide across a horizontal surface with a coefficient of friction mu. In this problem the lawnmower is pushed using a massless handle, which makes an angle theta with the horizontal. Assume that Fh, the force exerted by the handle, is parallel to the handle.

    Take the positive x direction to be to the right and the postive y direction to be upward.

    Find the magnitude, Fh, of the force required to slide the lawnmower over the ground at constant speed by pushing the handle.
    Express the required force in terms of given quantities.

    i have foudn the Fh which is Fh = W*µ/(cosΘ - µsinΘ)

    this is the question i need help with

    The solution for Fh has a singularity (that is, becomes infinitely large) at a certain angle Θcritical. For any angle Θ>Θcritical, the expression for Fh will be negative. However, a negative applied force Fh would reverse the direction of friction acting on the lawnmower, and thus this is not a physically acceptable solution. In fact, the increased normal force at these large angles makes the force of friction too large to move the lawnmower at all.

    Find an expression for tan(Θcritical).
     
  2. jcsd
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Can you help with the solution or looking for help too?
Draft saved Draft deleted



Similar Discussions: Pushing a lawnmower. picture included
Loading...