- #1
drummerjason
- 2
- 0
Homework Statement
A box slides down a 30.0 degree ramp with an acceleration of 1.20 m/s^2. Determine the coefficient of kinetic friction between the box and the ramp.
Homework Equations
The Attempt at a Solution
Ok so what i did was different from what my teacher has, but I can't explain it.
(the answer is supposed to be .436, which is what i got)
1) F=m(9.81)(sin30.0) ...divide by m... a=4.9m/s^2 that would be the ramp with no friction right?
2) so then... F_k=(a_withoutfriction-a_with friction)m --> F_k (4.9-1.2)m= (3.7m/s^2)(m) and that would be the force of kinetic friction (I think).
3) [tex]\mu[/tex]=F_k/F_n --> (3.7)(m)/(9.81)(cos30)(m)= .436
Ok so i got the right answer but I can't explain it. Just for starters, why in step 1, did it have to be sin30? would it be cos30 to find the accleration in the x direction?