When lifting the load, work A = 720 kJ was performed for a time interval t = 3 min. Determine the engine power of the hoist.

Given:

A = 720 kJ – work done by the hoisting machine during the time interval t;

t = 3 minutes – time span.

It is required to determine W (Watt) – the power of the engine of the lifting machine.

Let’s translate the units of measure of work and time into the SI system:

A = 720 kJ = 720 * 1000 = 720,000 Joules.

t = 3 minutes = 3 * 60 = 180 seconds.

Then, to determine the engine power, you must use the following formula:

W = A / t;

W = 720,000 / 180 = 72,000 / 18 = 4000 watts (4kw).

Answer: The engine power of the hoisting machine is 4000 watts (4 kW).