Friction of a piano?

Question

A piano with a mass of 250 kg is pulled up a ramp lying on the stairway of a house. The ramp is 6 meters long and the coefficient of sliding friction is .180. If the plank makes an angle of 42 degrees with the horizontal, find:

a. the force of friction (N)
b. the force required to pull the piano (N)
c. the work done in pulling it up to the top (J)
d. the potential energy acquired

Answer 1

a) The normal force is
m*g*cos(th)
and friction is
f= 250*9.81*cos(42)*0.18
f=328 N
b) The force to move the piano at a constant speed
F=250*9.81*sin(42)+f
F=1969 N
c) The work is
F*6
11814 J

d) PE gained is
250*9.81*6*sin(42)
9846 J
j