Question

An elevator uses 100 000J of electrical energy to raise a load of 800 N through a height of 40m in a time of 20s. What is the rate of conversion of the electrical energy to other forms?

Answer 1

`W_(out)=F\cdot d=800\cdot40=32000`
`P_(out)=(W_(out))/(t)=(32000)/(20)=1600W`
`\begin{gathered} P_(in)=(W_(in))/(t)=(100000)/(20)=5000W \\ \end{gathered}`

Therefore:

`P_(out):P_(in)=(P_(out))/(P_(in))=(1600W)/(5000W)=0.32`

Answer:

1600W