An electric motor powered by a 240V mains supply requires of 30A to lift a load of mass 3 tonnes at the rate of 5m per minute.

Calculate
(a). The power input
(b). The power output
(c). The overall efficiency of a machine.
Help me please!

1 answer

(a) To calculate the power input, we can use the formula:

Power input = voltage x current

Power input = 240V x 30A
Power input = 7200 W or 7.2 kW

(b) To calculate the power output, we can use the formula:

Power output = (force x distance) / time

First, we need to calculate the force required to lift the load:
Force = mass x acceleration due to gravity
Force = 3000 kg x 9.81 m/s^2
Force = 29430 N

Next, we can calculate the power output:
Power output = (29430 N x 5m) / 60s
Power output = 2452.5 W or 2.4525 kW

(c) To calculate the overall efficiency of the machine, we can use the formula:

Efficiency = (Power output / Power input) x 100%

Efficiency = (2452.5 W / 7200 W) x 100%
Efficiency = 0.34 x 100%
Efficiency = 34%

Therefore, the overall efficiency of the machine is 34%.