While a roofer is working on a roof that slants 36 degrees above the horizontal, he accidentally nudges his 85.0 N toolbox, causing it to start sliding downward, starting from rest. If it starts 4.25m from the lower edge of the roof, how fast will the toolbox be moving just as it reaches the edge of the roof if the kinetic friction force on it is 22.0 N?

2 answers

Well, first find the net accelerating force

Net accelerationforce= weight down the plane - friction
mgSinTheta - 22

Set that equal to mass*acceleration and solve for acceleration.

then:
Vfinal^2=Vinitial^2+2*a*d
(Vinitial is zero
solve for Vfinal
23