**Contents**show

## What do you mean by efficiency of a heat engine write its formula?

The Efficiency of a Heat Engine Formula**η = Thermal efficiency.** **W = Useful work obtained**. QH = Given amount of heat energy. This is known as the heat engine formula. According to the second law of thermodynamics, it is impossible to get 100 percent of the thermal efficiency.

## What is heat engine formula?

The useful work done by a heat engine is **W = Q _{1} – Q_{2} (energy conservation)**. An ideal reversible engine does the maximum amount of work. … You can convert a fraction of the heat into work if you have a place at a lower temperature T

_{2}where you can dump some of the heat.

## What is the formula for efficiency?

Efficiency is often measured as the ratio of useful output to total input, which can be expressed with the mathematical formula **r=P/C**, where P is the amount of useful output (“product”) produced per the amount C (“cost”) of resources consumed.

## What is Carnot efficiency formula?

**efficiency =WQH=1−TCTH**. These temperatures are of course in degrees Kelvin, so for example the efficiency of a Carnot engine having a hot reservoir of boiling water and a cold reservoir ice cold water will be 1−(273/373)=0.27, just over a quarter of the heat energy is transformed into useful work.

## How will you define heat?

Heat is **the form of energy that is transferred between systems or objects with different temperatures** (flowing from the high-temperature system to the low-temperature system). Also referred to as heat energy or thermal energy. Heat is typically measured in Btu, calories or joules.

## Why are heat engines inefficient in general?

Why are heat engines inefficient, in general? … **Heat engines attempt to convert the worst source of energy into the best.**

## Why is efficiency less than 100?

Efficiency is the percent of work put into a machine by the user (input work) that becomes work done by the machine (output work). **The output work is always less than the input work because some of the input work is used to overcome friction**. Therefore, efficiency is always less than 100 percent.

## What is SI unit of entropy?

The SI unit of entropy is **joules per kelvin**.

## What is the difference between work and heat?

This distinction between the microscopic motion (heat) and **macroscopic motion** (work) is crucial to how thermodynamic processes work.

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Main Differences.

Work (W) | Heat (Q) | |
---|---|---|

Requires | Force and Displacement | Temperature difference |

Process | Macroscopic pushes and pulls | Microscopic collisions |