- 13

- 0

**[SOLVED] Non conservative forces: work + coefficient of static friction**

hey guys, I've been having a little trouble with some parts of this problem, hope someone can point me in the right direction

A 20[kg] sled starts up a 30 degrees incline with a speed of 2.4[m/s] the coefficient of kinetic friction is 0.25.

A) How far up the incline does the sled travel?

B) What condition must you put on the static coefficient if the sled is not to get suck at the point determined in part a?

C) If the sled slides back down what is its speed when it returns to its starting point?

Know: m = 20 [kg]

theta = 30 degrees

v (initial) = 2.4 [m/s]

Mu(k) = 0.25

Ok, so I did part A): I found the net work and how far the sled went up the incline.

Part B) threw me off a little bit. By condition I assume I have to find an angle? Or maybe a range for the coefficient?

What I did was carry out tan(theta) = Mu(s) plugged in 30 degrees for theta and got

Mu(s) = .577 and then said that the condition was that M(s) < .577 is that right?

Part C) Here I wasnt sure if I should use kinematics or conservation of energy equations. There's a friction force which is nonconservative, but I'm not sure how to incorporate this. Any help would be appreciated