Homework Help: Incline Skier

1. Oct 8, 2007

HT3

1. The problem statement, all variables and given/known data
A skier is gliding along at 3m/s on horizontal frictionless snow. He suddenly starts down a 10 degree incline. His speed at the bottom is 15 m/s.
a) what is the length of the incline?
b) how long does it take for him to reach the bottom?
we know:
Vo=3m/s
Vf=15m/s
t=?
x=?
a=?

2. Relevant equations
V^2=Vo^2 +2ax

3. The attempt at a solution
i need help to find what the a is...and why it is that.

2. Oct 8, 2007

bob1182006

the only force acting on the skier is gravity but since the skier is going down a 10 degree incline gravity is giving him some acceleration but not 100% of it's full foce.

draw the Free Body Diagram and split up gravity into it's components where the acceleration will be parallel to the incline.

3. Oct 8, 2007

HT3

okay from my freebody diagram i get sin(10)=9.8/a
a=56.4
and that is wrong....if anyone could explain to me how to do it properly please...id greatly appreciate it because i have my exam very soon.

4. Oct 8, 2007

bob1182006

it should be 9.8*sin(10). the force acting parallel to the inclined plane is mgsin(theta).