The 20 kg case is hoisted up the 20o incline by the pulley system and motor M. The case starts from rest and attains a speed of 4m/s after 10 m travel along the plane at constant acceleration. Determine the power that must be supplied to the motor at the instant the case has moved 10m.The motor works with a efficiency of 0.8.

1) 415.52 W.
2) 213.45 W.
3) 123.76 W.
4) 764.37 W.

Kinematics:
v2 = vo2 + 2as;
42 = 02 + 2a(10);

a = 0.8m/s2.

Equation of motion :


Power:
P =F.v = 83.1(4) = 332.42 W.
Power input to the motor = (power output)/e
= 332.42/0.8 = 415.52 W.