Chapter 14, Problem 46GP

To determine

To find: Amount of coal require.

Answer to Problem 46GP

  $9523$ kg

Explanation of Solution

Given Data:

Energy given by coal $30$ MJ/kg

Efficiency $=70\%$

Formula used:

  $\text{efficiency\%=}\frac{\text{output}}{\text{input}}\text{×100}$

Calculation:

  $\frac{\text{out put}}{\text{input}}\times 1w=\text{efficiency \%}$

  $\Rightarrow \text{out put heat =}\frac{70\times 30}{100}$ MJ/kg

  $\Rightarrow \text{out put heat =}21$ MJ/kg

  $\Rightarrow \text{Amount of coal = }\frac{2\times {10}^5}{21}=0.09523\times {10}^5$

  $\Rightarrow \text{Amount of coal = }9523$ kg

Conclusion:

Hence $9523$ kg amount of coal needed.