A box of mass 14.3 kg with an initial velocity of 1.32 m/s slides down a plane, inclined at 20 with respect to the horizontal. The co efficient of kinetic friction is 0.51 The box stops after sliding a distance 017 (part 6 of 6) 10.0 points What is the magnitude of the average power generated by friction from start to stop?
2 answers
A distance of what????
Initial Ke = (1/2) m v^2
Initial Pe relative to finish point = m g * (distance* sin 20)
Sum is Total initial energy
At the finish point both the Ke and the Pe are zero. Their sum is the work done by friction.
You otherwise could calculate that distance knowing the coef of friction
Friction force = mu m g cos 20
weight component down slope = m g sin 20
net force down slope = m g (sin 20 - mu cos 20) = m a
I assume a comes out negative (braking)
so at stop
0 = 1.32 + a t
solve for t
then average speed = 1.32 / 2
distance down slope = average speed * t
Initial Pe relative to finish point = m g * (distance* sin 20)
Sum is Total initial energy
At the finish point both the Ke and the Pe are zero. Their sum is the work done by friction.
You otherwise could calculate that distance knowing the coef of friction
Friction force = mu m g cos 20
weight component down slope = m g sin 20
net force down slope = m g (sin 20 - mu cos 20) = m a
I assume a comes out negative (braking)
so at stop
0 = 1.32 + a t
solve for t
then average speed = 1.32 / 2
distance down slope = average speed * t
2 answers