Question

An engineer claims to have made an engine delivering 10 kW power with fuel consumption of $1\,gs^{-1}$. The calorific value of fuel is 2 $kcalg^{-1}$. This claim is

• A. valid
• B. invalid
• C. dependent on engine design
• D. dependent on load

Answer 1

Answer: (B)

invalid

Answer 2

$P_{output}=10kW$
$p_{input} =2\times 10^3 cal g^{-1} \times 1 gs^{-1}$
= 2 $\times10^3 cals^{-1}$
= $2\times 10^3 \times 4.2 Js^{-1}$
=8.4 kW
As,$P_{output} > P_{input}$, hence it is never possible