Mechanical equivalent of heat

Definition

The mechanical equivalent of heat is the amount of mechanical energy needed to produce an equivalent amount of heat. It establishes a relationship between mechanical work and heat, quantified as 1 calorie being equal to approximately 4.184 joules.

5 Must Know Facts For Your Next Test

1. James Prescott Joule conducted experiments that led to the determination of the mechanical equivalent of heat.
2. The value of the mechanical equivalent of heat is approximately 4.184 joules per calorie.
3. This concept supports the principle of conservation of energy, indicating that energy can be converted from one form to another but cannot be created or destroyed.
4. Joule's experiments often involved stirring water with a paddle wheel driven by falling weights to measure the temperature increase due to mechanical work.
5. The relationship can be expressed mathematically as $Q = W$, where $Q$ is heat and $W$ is work, both measured in joules.

Review Questions

• What is the numerical value of the mechanical equivalent of heat in joules per calorie?
• Who was the scientist responsible for determining the mechanical equivalent of heat?
• How does the concept of mechanical equivalent of heat support the principle of conservation of energy?

Related terms

Calorie: A unit of energy defined as the amount needed to raise the temperature of one gram of water by one degree Celsius.

Joule:

The SI unit of work or energy, equal to one newton-meter.

Conservation of Energy:

\text{A fundamental principle stating that energy cannot be created or destroyed, only transformed from one form to another.}