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: I can't solve this at all. please help

  1. Nov 11, 2009 #1
    while moving in, a new homeowner is pushing a box across the floor at constant velocity. the coefficient of kinetic friction between the box and the floor is 0.41. the pushing force is directed downward at an angle (theta) below the horizontal. when theta is greater than a certain value, it is not possible to move the box, no matter how large the pushing force is.

    find that value of theta.

    I tried this.

    P= pushing force
    x = theta
    m = mass of box
    g= 9.8 or accel of gravity

    Pcosx = (Psinx +mg).41

    no luck :(
  2. jcsd
  3. Nov 12, 2009 #2
    Well you're nearly there. If the pushing force is very large then Psinx >> mg and you can ignore
    the weight of the box.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook