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: The force of friction moving up a slope

  1. Oct 19, 2008 #1
    A grocery cart is being pushed with a force of 450 N at an angle of 30.0 degrees to the horizontal. If the mass of the groceries is 42 Kg,
    (a) Calaculate the force of friction if the coefficient is 0.60.

    Alright guys I have been doing this problem for around two hours. My physics teacher isn't a good teacher and I have no idea how to get the right answer(located in the back of book).

    Ive tried all I can think of,
    Ff= (0.60)(450n)
    = 270n

    450 COS 30
    = 389.7 N
    and a bunch of othe stuff I erased off my paper

    The answer in the back is 3.8 x 102 or around 380 n
  2. jcsd
  3. Oct 19, 2008 #2


    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    What is the mass of the cart and groceries?
  4. Oct 19, 2008 #3
    it doesn't say just assume 42kg I geuss
  5. Oct 20, 2008 #4


    User Avatar
    Homework Helper

    The 450 N force has 2 components. There is the Cos30 component forward, but there is also the Sin30 component down. Sin30*450 N + 42*(9.8) N = 225 + 411.6 N = 636.6 N in the downward direction.

    Then you use your coefficient of friction based on the total downward force.
  6. Oct 20, 2008 #5
    yah, thanks. I figured it out last night. I drew a diagram
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook