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: Forces and Graphs

  1. Feb 9, 2012 #1
    So the problem is that i have a physics test coming up and its about forces and graphs.
    The teacher can not explain the different formulas clearly which results in everyone getting bad grades. I wonder if anyone can explain this to me.


    2. Relevant equations
    A RCXD (a little car with explosives controlled by a joystick) drives down a hill with an angle of 30°. Its mass = 5kg. What is its acceleration if the driving force ( force motrice in french) = 300[N] and the friction = 100[N]?


    3. The attempt at a solution

    FM (driving force) -f (friction) = 0 ?
    300-200 = 0 -> 100 = 0 so not possible >.<
     
    Last edited: Feb 9, 2012
  2. jcsd
  3. Feb 9, 2012 #2

    tiny-tim

    User Avatar
    Science Advisor
    Homework Helper

    Welcome to PF!

    Hi Thepotatis! Welcome to PF! :wink:

    Nearly all dynamics questions are solved by applying good ol' Newton's second law (Ftotal = ma), in one or more directions …

    in this case, there are at least three forces making up Ftotal: the driving force, the friction, and the weight :smile:
     
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook