- #1
flatline4520
- 2
- 0
Homework Statement
A sled moves on the flat surface of a hill. The hill makes an angle θ with the horizontal, and is left orientated.
The hill: θ = 60°; left oriented; μk = 0.1.
The sled: mass = 20 kg; starting location = 20 m from the bottom of the hill;
initial speed = 0 m/s .
http://img26.imageshack.us/img26/1756/blockoninclineleft.jpg
Solve:
- (Fnet)x immediately after motion begins, (N)
- (Fnet)x, sliding down the hill, (N)
Homework Equations
[tex]
\vec{F}_{net} = \Sigma \vec{F} = m \vec{a}
[/tex]Fn = mg cos θ
Fn = 98
The Attempt at a Solution
I draw an FBD and every time I solve for (Fnet)x I get:
(Fnet)x = -mg sin θ - μk*Fn
(Fnet)x = 59.742 - 9.8
(Fnet)x = 49.9 N
Every time I input that as my answer it says it's wrong. Also why is it that the kinetic friction force is a positive 9.8. Doesn't the friction go in the opposite direction of the motion?
Thanks for help
Last edited by a moderator: