Question

In Joule's experiments, the equivalence of heat and mechanical work was demonstrated, establishing the mechanical:

• A. Advantage of heat engines
• B. Equivalent of heat
• C. Energy conservation principle
• D. Work principle in thermodynamics

Hint:

Joule’s experiments linked mechanical work to heat, establishing the mechanical equivalent of heat — a milestone in the foundation of thermodynamics.

Answer 1

The Correct Option is B

Step 1: James Prescott Joule conducted a series of experiments in the mid-19th century demonstrating that heat and mechanical work are interchangeable forms of energy.
Step 2: He established the concept of the “mechanical equivalent of heat,” which quantifies the amount of mechanical work needed to produce a unit of heat. One of his famous experiments involved stirring water with a paddle wheel and measuring the temperature rise due to mechanical work.
Step 3: This work was fundamental to the development of the first law of thermodynamics (conservation of energy), but the specific term he introduced was the “mechanical equivalent of heat.”
Why the other options are incorrect:

• (A) Heat engine performance was not the focus of Joule’s experiments.
• (C) While his work supported the energy conservation principle, the direct term is "mechanical equivalent of heat."
• (D) “Work principle” is not a standard or established term in this context.