Skier down a slope problem

  • Thread starter Mirole
  • Start date
  • #1
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Homework Statement


You, a 75-kg skier, glide straight down a snow-covered slope inclined at 15 degrees to the horizontal over spring break. Let's be realistic, what is your acceleration(magnitude and direction) Assume your skis are wood and the snow is dry. mu_k on snow is 0.060.


Homework Equations


Fnet=ma


The Attempt at a Solution


Fx = -fk+mgsin[tex]\theta[/tex] = ma
Fy = n = mgcos[tex]\theta[/tex]

-mu_k*mgcos[tex]\theta[/tex] = ma - mgsin[tex]\theta[/tex]
a = -mu_k*g*cos[tex]\theta[/tex] + gsin[tex]\theta[/tex]
a = (.060)(9.8)cos15 + 9.8sin15
a = 8.22 m/s2

Did I do the first part right? And, how would I find the direction?
 

Answers and Replies

  • #2
Delphi51
Homework Helper
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a = -mu_k*g*cosθ + gsinθ
a = (.060)(9.8)cos15 + 9.8sin15
Looks like you dropped a minus sign in that step.
The friction force opposes the parallel component of gravity, so there ought to be subtraction rather than addition.
 
  • #3
33
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Wow, I did that by mistake and didn't even catch it. Thanks, so would 1.97m/s2 be correct?
 

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