(adsbygoogle = window.adsbygoogle || []).push({}); Mechanical Energy question (Skier going down a slope...confusing!!)

First of all, I apologize ahead of time if my question seems to be really simple, but I have been working on it for at least two hours and still no progress (which is why this post made so late lol). My class has been working on standard/semi easy Mechanical energy questions and there was a day when we were tossed with this question that I feel was never covered. I've tried to solve this with several of my friends, but no luck.

Here is the question:

A skier takes off from the top of a slope 30.0m vertically above the bottom with an initial velocity of 1.90 m/s. The length of the slop along the surface to the bottom is 50.0m. During the ski run, the skis have an average frictional force exerted on them equal to one-third times the gravitational force. Calculate the velocity of the skier at the bottom of the hill.

What I first noticed was that the Slope seemed to be in a 3:4:5 ratio. So the angles of the slope would be 90 degrees, 30 degrees, and 60 degrees.

What I tried to do was...

1.Take gravity and mutiply it by 1/3 resulting of a average frictional force of about 3.27

2.Use the equation for WorkNet: WorkNet=∆KE

=Final Kinetic Energy - Initial Kinetic Energy

=(1/2 * mass * final velocity²) minus (1/2 * mass * inital velocity²)

3.Find WorkNet:

WNet= |Fa||d|cosѲ + |Ff||d|cosѲ

*I ended up with a negative number but I pretended it was in absolute values*

4.Changed "WorkNet=(1/2 * mass * final velocity²) minus (1/2 * mass * inital velocity²)" algebraicly so that Vf= √InitalVelocity + 2*WNet

...and from there I ended up with a final velocity of 16.7m/s

Again I apologize if this question seems simple... it's just that I have no idea what to do. I hope the method I took was correct and ended up with the answer. If not, any advice would be greatly appreciated. I'd like to know the solution by a fellow member.

Thanks in advance!!

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# Homework Help: Mechanical Energy question (Skier going down a slope confusing )

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