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: Help with newtons laws and friction

  1. Jan 28, 2009 #1
    1. The problem statement, all variables and given/known data
    a girl is skiing down a 35 degree inclined hill that is 120 meters long. She starts from rest and the snow has a coefficient of friction of .12.
    A. Draw an FBD
    B what is her acceleration
    c. How much time dows it take her to travel the 120 meters

    2. Relevant equations
    I am unsure on how to set up the question solution. I think it's CAE's that are used as well, but i am completely unsure.

    3. The attempt at a solution
    ΣF= MA
    vi= 0m/s
    ΛD=120 m
    vf = ?
    120cos35= 98.29????
    120sin35= 68.82????

    If anyone could please help i would really appreciate it. If i can figure out how to set this problem up and solve it, i will be able to figure the other problems out. Thank you so much!!
    I don't think there's enough to solve it using cae's can i use the sin and cosine functions with the 35 degrees??
  2. jcsd
  3. Jan 28, 2009 #2
    You have to take her direction of motion into consideration. If you've drawn a FBD you see that there's a difference in the direction of the forces that have an effect on her acceleration. If you can take this into consideration?
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook