- #1
Carrie
- 27
- 0
Homework Statement
A 4.00-kg block rests on a 30.0 degree incline. If the coefficient of static friction between the block and the incline is 0.700, with what magnitude force must a horizontal force act on the block to start it moving up the incline?
Homework Equations
F=ma
Ffriction=μs*Fnormal
The Attempt at a Solution
I attached the force body diagram I did.
Fy
Fn - mgsin(30) = 0
Fn = mgsin(30)[/B]
Fx
Ffr - FA = 0
Ffr = FA
μ*N = FA
mgsin(30) + .7*mgcos(30)) = FA
(4)(9.8)sin(30)+.7*(4)(9.8)cos(30) = FA
FA = 43.36 N
However, the answer is 84.1 N. I'm pretty rusty with this stuff. Thank you!