Question

A cargo elevator on Earth (where g = 10 m/s2) lifts 3000 kg upwards by 20 m. 720 kJ of electrical energy is used up in the process. What is the efficiency of this process?

Answer 1

Answer: 83%

Explanation:

Efficiency of the process = work output/work input × 100%

Work input is the energy used up in the process = 720,000Joules

Work output = Force × distance

= (3000×10)× 20

= 600000 Joules

Efficiency= 600000/720000 × 100

= 0.83×100

= 83%