Question

An electrical motor is used to raise an object. The object transfers 150J of useful energy when the motor is supplied with 250J of electrical energy.
A) what is total energy supplied to the motor?
B)what is the useful energy transfer?
C) what is the efficiency?

Answer 1

Answer:

A) 250 J

B) 150 J

C) The efficiency = 0.6 and the percentage efficiency = 60%

Explanation:

The question relates to definition of terms in energy transfer and the calculation of efficiency

The parameters of the given are;

The energy the object transfers = 150 J

The amount of electrical energy supplied to the motor = 250 J

Therefore, we have;

A) The total energy supplied to the motor = The amount of electrical energy supplied to the motor = 250 J

B) The useful energy transferred = The energy used to do work = 150 J

C) The efficiency = (Useful energy transferred (out))/(Total energy supplied (in)

$The \ efficiency = \dfrac{Useful \ energy \ transferred \ (out)}{Total \ energy supplied \ (in)} = \dfrac{150 \, J}{250 \, J} = 0.6$

The percentage efficiency is given as follows;

$The \ percentage \ efficiency = \dfrac{Useful \ energy \ transferred \ (out)}{Total \ energy supplied \ (in)} \times 100$

$\therefore The \ percentage \ efficiency = \dfrac{150 \, J}{250 \, J} \times 100 = 0.6 \times 100 = 60\%$

Answer 2

Answer:

A) 250 J

B) 150 J

C) efficiency = 0.6, percentage efficiency = 60%

Explanation: