Which of the following causes a hot air balloon to rise?
Resistance
Conduction
Convection
Radiation
Convection
To determine which of the following causes a hot air balloon to rise, let's first understand the principles behind each term.
1. Resistance: Resistance refers to the opposition that a material or object encounters when moving through a medium. In the context of a hot air balloon, resistance is not directly involved in causing it to rise.
2. Conduction: Conduction is the transfer of heat between objects that are in direct contact with each other. Although conduction is involved in heating the air inside the balloon, it does not directly cause the balloon to rise.
3. Convection: Convection is the transfer of heat through the movement of a fluid (liquid or gas). In the case of a hot air balloon, convection plays a crucial role in causing it to rise. When the air inside the balloon is heated, it becomes less dense than the surrounding cool air. This creates a buoyant force that lifts the balloon upwards.
4. Radiation: Radiation is the transfer of heat through electromagnetic waves without the need for a medium. While radiation is involved in the transfer of heat to the balloon, it is not the direct cause of the balloon's ascent.
Therefore, the correct answer is convection. Convection is the process by which the heated air inside the balloon becomes less dense and rises, causing the balloon to ascend.