(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

A ski starts from rest and slides down a 22^{o}incline 75 m long. a) if the coefficient of friction is 0.090, what is the ski's speed at the base of the incline? b) If the snow is level at the foot of the incline and has the same coefficient of friction, how far will the ski travel along the level? Use energy methods.

2. Relevant equations

-W_{nc}= (KE_{f}- KE_{o}) + (PE_{f}- PE_{o})

3. The attempt at a solution

a)Since the hypotenuse of the incline is 75 m, and the angle relative to the horizontal is 22^{o}, the vertical height is 75 sin22^{o}= 28.1 m.

PE_{f}and KE_{o}cancel out, and the equation becomes:

PE_{o}= KE_{f}+ W_{nc}

That simplifies to:

mgh = (1/2)mv^{2}+ umgcos22^{o}-- (u is coefficient of friction)

masses cancel out

(9.8)(28.1) = (1/2)v^{2}+ (0.09)(9.8)cos22^{o}

v = 23.4 m/s -- According to the book, the answer is 21 m/s. What am I doing wrong??

b) KE_{f}= umg * d?

**Physics Forums | Science Articles, Homework Help, Discussion**

Dismiss Notice

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Homework Help: Conservation of energy problem(s)

**Physics Forums | Science Articles, Homework Help, Discussion**