Posted by Unknown on Monday, June 16, 2014 at 9:04pm.
a motor lifts a 12 kg mass to a height of 15 meters at a content velocity in 3.5 seconds.
a) find the power
b) if the motor is only 35% efficient find the input energy

Physics  Damon, Monday, June 16, 2014 at 9:15pm
change in potential energy = m g h = 12 * 9.81 * 15 = 1766 Joules
power = joules per second = 1766/3.5 =505 Watts
Input power = 505/.15 = 3363 Watts
Input energy = 3363 Watts * 15 seconds = 50,451 Joules