Question

Gravitational force is required for

• A. stirring of liquid
• B. convection
• C. conduction
• D. radiation

Answer 1

The Correct Option is B

To understand which phenomenon among the given options requires gravitational force, let's explore each concept briefly:

1. Stirring of liquid: This process involves a mechanical action to mix two substances. It does not inherently require gravitational force; instead, it relies on external mechanical energy.
2. Convection: Convection is a mode of heat transfer where warm fluid rises and cooler fluid descends due to differences in density mostly caused by temperature variations. Gravitational force is crucial here as it allows for the movement of fluid masses based on density differences. The warm fluid rises because it is less dense, and the cool fluid sinks because it is denser. The gravitational force enables this density-driven flow, hence making convection dependent on gravity.
3. Conduction: This is the process of heat transfer through direct contact between molecules, without any movement of the material as a whole. Gravitational force does not play a role in conduction.
4. Radiation: Radiation is the transfer of energy through electromagnetic waves and does not require a medium or gravitational force to occur. Heat from the sun reaches Earth primarily through radiation.

Based on these explanations, gravitational force is specifically required for convection, making it the correct answer.