Johnny jumps off a swing, lands sitting down on a grassy 20 degree slope, and slides 3.5m down the slope before stopping. The coefficient of kinetic friction between grass and the seat of Johnny's pants is 0.5
Frictional force = [tex]\mu[/tex]N
V final is the first V and V intial is the second V
Sorry about the equations, I'm still inexperienced with Latex.
Also, you may use any kinematic equation or Newtons equations. I listed these because this is how I approached the problem.
3. The Attempt at a Solution
Ok, I thought/think this was/is a very easy problem. However, masteringphysics.com does not agree with my answer. Hopefully someone can point out my errors.
I'm not sure exactly where to start. Breaking the forces into vectors gives me:
Force Johnny (mgcos(20),0)
Is this the correct breakdown?
I know that the net force is 0 because Johnny eventually stops. I know that Frictional force is heading up parallel to the slope of the grass. I'm pretty sure the Frictional force is .5m9.8cos(20) where m is the mass of Johnny. I evaluated that to get that the force of friction is 4.6m. Here is where I run into all of my problems. I know that I want to find the acceleration in order to solve for the initial velocity. I think there is something wrong with my vectors. Could someone give me a push in the right direction in order to solve for acceleration?