Question

In one hour, coal supplies 500 000 J of energy. The energy amounts to 380 000 J. How much useful energy is produced in one hour?

Answer 1

To find the useful energy produced in one hour, we need to find the efficiency of the coal power plant. The efficiency can be calculated by dividing the energy produced by the energy supplied by coal. The useful energy is then found by multiplying the efficiency with the total energy input.

Step-by-step explanation:

To calculate the useful energy produced in one hour, we need to find the efficiency of the coal power plant. Efficiency is defined as the useful energy output divided by the total energy input. In this case, the energy supplied by coal in one hour is 500,000 J. The energy produced by the power plant is 380,000 J. To find the useful energy, we can use the formula:

Useful energy = Efficiency * Total energy input

Given that the energy supplied by coal is the total energy input, we can rearrange the formula to:

Useful energy = Efficiency * 500,000 J

Now, let's find the efficiency using the given information:

Efficiency = (Energy produced / Energy supplied by coal) * 100%

Efficiency = (380,000 J / 500,000 J) * 100%

Efficiency = 76%

Now we can calculate the useful energy:

Useful energy = 76% * 500,000 J

Useful energy = 380,000 J

Answer 2

120,000J

Corrected question;

In one hour, coal supplies 500 000 J of energy. The wasted energy amounts to 380 000 J. How much useful energy is produced in one hour?

Step-by-step explanation:

Given;

Total energy Et = 500,000 J

Wasted Energy Ew = 380,000J

The amount useful energy is the amount of energy that is available for supply.

This can be derived by subtracting the wasted energy from the total energy.

Useful energy = Total Energy - wasted energy

Eu = Et - Ew

Substituting the given values;

Eu = 500,000J - 380,000

Eu = 120,000 J

The amount of useful energy produced in one hour is 120,000 J