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!

Im Dead

  1. Jun 3, 2007 #1
    :cry: Im riting a fisix exam on Toosday and im officially Screwed!!!

    I cant do vectors and incline planes at all

    im going to die:cry:

    Please help:bugeye:

    Here's probly tha simplest problem in the world... and i can't do it...

    a 20 kg box is released on a 30 degree incline with an acceleration of o.25m/s.
    wots tha force of friction impeding its motion?

    Yes, i am stooopid.
  2. jcsd
  3. Jun 3, 2007 #2

    F(gravity)=mg. Component along plane is mg sin 30. (Component normal to plane is mg cos 30). Remember which way around those are by considering if the angle was 0 (sin 0 = 0, cos 0 = 1).

    F(friction)=uN, where the normal force N must equal the normal component of gravity (otherwise it would move into or off from the surface).

    Combining those, total force along the plane is simply the gravity component minus friction. Also the total force is F=ma.
  4. Jun 3, 2007 #3

    Meir Achuz

    User Avatar
    Science Advisor
    Homework Helper
    Gold Member

    Draw a good free body diagram.
    Start with the basics.
  5. Jun 3, 2007 #4
    i reeli, reeli wish dat i cud say..." Thanks, guys, i got it!!" ... but i cant.

    thanks anyway... i'll just have to create sum Awesome crib notes for Toosday. Actually, i got a friend who'd do tha test for me... nd let me rite my name on it.

    Actually... I Got it!!! Yippy!!! Thanks, guys, I got it!!!" lol
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?

Similar Discussions: Im Dead
  1. Im stuck! (Replies: 1)

  2. Dead load (Replies: 1)