- #1
JessicaHelena
- 188
- 3
Homework Statement
A block of mass M is at rest on an incline that makes angle theta with the horizontal. Given that the static coefficient of friction is mu_s1 and the kinetic coefficient friction mu_k, what is the magnitude of the force of static friction exerted on the block by the incline?
a) mu_s1 M g cos theta
b) mu_s1 M g tan theta
c) Mg sin theta
d) Mg / than theta
Homework Equations
F_f = mu * F_N
F_net x = 0
F_net y = 0
The Attempt at a Solution
Using that F_f = mu * F_N, since the block will have F_n = Mg cos theta due to F_net y = 0,I thought that F_f = mu_s1 * Mg cos theta, which is a). However, it is apparently choice c), and while I can see that using F_net x = 0, I don't get why a) would be wrong.