Posted by Vishnu on .
A skier is gliding along at 1.13 m/s on horizontal, frictionless snow. He suddenly starts down a 13.1° incline. His speed at the bottom is 18.8 m/s. What is the length of the incline?

Use his change in kinetic energy to get his loss of potential energy. The equation
g H = change in (V^2)/2
can be used to het the height change, H.
H and the slope angle can be used to get the length L of the incline.
H/L = sin 13.1

My attempt:
H/L = sin 13.1
L = sin13.1 / H
= sin13.1 / 18.8 m/s
= 0.01 km = 10 m
Why is this answer incorrect?
Responses
physics  drwls, Wednesday, October 8, 2008 at 2:10am
Your equation L = sin13.1 / 18.8 m/s
is totally wrong. You cannot have a length on one side of an equation and 1/Velocity on the other side. It is not even dimensionally correct. You did not follow the method suggested. Where did the L = 0.01 km come from?
The change in V^2/2 is (18.8^2  1.13^2)/2 = 176.1 m^2/s^2
That equals the change in gH
The change in H is therefore
176.1 m^2/s^2 / 9.8 m/s^2 = 18.0 m
physics  Luckna, Wednesday, October 8, 2008 at 9:35am
This answer still shows up as incorrect

physics 
drwls,
I computed H for you. They asked for the length L of the incline. Did you do the final step to get L?
We usually don't do complete answers for students. We try to teach you the method to solve problems yourself. 
physics 
bobpursley,
I agree with DrWLS.

physics 
Vishnu,
Can i have the formula for this step please?

physics 
bobpursley,
You know h is the height, you know the angle, and you are looking for the hypotenuse. Could the formula be the sine function?

physics 
Vishnu,
h =18.0 m
angle = 13.1°
hypotenuse = ?
Sine function formula is:
Opposite / hypotneuse
What is opposite?