Question

An engine with an input temperature of 755K and an exhaust temperature of 453K has the same efficiency as an engine that is 40% efficient. Is this true or false? I am having trouble

Answer 1

Efficiency is usually defined as a benefit divided by a cost. Or in terms of temperature:

e=1−T cold/T hot

Here, you are given both temperatures, so you just need to plug them in, and then compare to 40%. You will get a decimal for 'e', so you'll have to multiply by 100 to get a percentage.

Answer 2

True

Step-by-step explanation:

The efficiency of a heat engine is defined as the ratio of work done by the energy to the input energy.

It is given by

`\eta = (W)/(Q_(1))`

Where, W is the work done and Q1 is the input heat.

`\eta = 1-(T_(2))/(T_(1))`

Where, T2 is the temperature of cold reservoir and T1 is the temperature of hot reservoir.

Here, T1 = 755 K and T2 = 453 K

So, efficiency =
`\eta =1-(453)/(755)`

efficiency = 40 %

So, it is true.