Question

An electric motor has a power rating of 1.50kW. If it operates at 65% efficiency, how much work can it do in one hour?

Answer 1

Answer on Question #41987 - Physics - Mechanics | Kinematics | Dynamics

Question.

An electric motor has a power rating of 1.50kW. If it operates at 65% efficiency, how much work can it do in one hour?

Given:

$N = 1.5\ kW = 1500\ W$ is a power of motor

$\eta = 0.65$ is an efficiency

$t = 1\ h = 3600\ s$ is a time of work

Find:

$A = ?$ is a work

Solution.

Power is the rate of doing work. It is equivalent to an amount of energy consumed per unit time.

$$N = \frac {A}{t}$$

But in our case useful power is:

$$N _ {e f f} = N \cdot \eta$$

So, for our problem:

$$N _ {e f f} = N \cdot \eta = \frac {A}{t} \rightarrow A = N \cdot \eta \cdot t$$

Calculate:

$$A = N \cdot \eta \cdot t = 1500 \cdot 0.65 \cdot 3600 = 3510 \cdot 10^{3} = 3.51 \cdot 10^{6} J = 3.51\ MJ$$

Answer.

$$A = N \cdot \eta \cdot t = 3.51 \cdot 10^{6} J = 3.51\ MJ$$

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