you slide a 325N trunk up a 20 degree inclined plane w/ constant velocity by exerting a force of 211 N parallel to the inclined plane

a) what is the comp. of the trunk's weight parallel to the plane?
b) what is the sum of the Fa, friction and the parallel comp. of the trunk's weight? Why?
c) What is the size and direct. of the Ff?
d) What is the coeff. of friction?

2 answers

a) 325 sin 20
b) it is not accelerating so the sum of forces in any direction is zero.
c)Call x positive up the plane.
The thing is moving up the plane, in the plus x direction
the friction force resists the motion so it acts down the plane, in the -x direction
Sum all forces to get the friction force
Force down ramp due to friction = Ff
Force down ramp due to gravity = 325 sin 20 N
Force up ramp due to you = 211 N
Sum of forces up ramp = 0
211 -Ff - 325 sin 20 = 0
solve for Ff directed down ramp
Ff = coef *325 cos 20
we just got Ff so solve for coef
A) 325sin(20)=111N
B) 0 -- because it's going in a constant velocity.
C)?
D)?