A forklift raises a 90.5 kg crate 1.80 m. (a) Showing all your work and using unity conversion ratios, calculate the work done by the forklift on the crane, in units of kJ. (b) If it takes 12.3 seconds to lift the crate, calculate the useful power supplied to the crate in kilowatts.

Part (a)

Step 1:

To calculate the work done by the forklift on the crane using unity conversion ratios

Mass of the crate m = 90.5 kg

Height h = 1.80 m

Acceleration due to gravity g = 9.81 m/s2

Step 2:

Work done = force x distance

The work is done against the gravity and the acceleration is equal to g. Hence the force is nothing but the weight. Therefore the Work done W

W = mgh

W = (90.5 kg) (9.81 m/s2 ) (1.80 m)

Step 3:

Our aim is to calculate the work done in KJ. unit of work done is J (joule) and also equals Nm. therefore (N = kgms-2)

W = (90.5 kg) (9.81 m/s2 ) (1.80 m)

W = KJ

W = 1.598 KJ

The work done by the forklift on the crane is 1.598 KJ

Part (b)

Step 1:

To calculate the useful power supplied to the crate in kilowatts

Time taken to lift the crane t = 12.3 s