I reposted this because Ayana posted it on another student's thread.
When the air under the envelope is heated, the balloon lifts. Which of the following statements is true?
A. Hot air balloons use radiation to rise.
B. Hot air balloons use conduction to rise.
C. Hot air balloons use convection to rise.
D.Hot air balloons use air resistance to rise.
(thank you ^^)
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posted by Ayana
today at 4:04pm
To determine which statement is true about how hot air balloons rise, we need to understand the different methods of heat transfer. The options given are radiation, conduction, convection, and air resistance.
A. Radiation is the transfer of heat through electromagnetic waves. Hot air balloons do not rely on radiation to rise, so option A is incorrect.
B. Conduction is the transfer of heat through direct contact. In the case of hot air balloons, they do not rely on direct contact with the ground or any other surface to rise, so option B is incorrect.
C. Convection is the transfer of heat through the movement of a fluid or gas. In the case of hot air balloons, they rely on convection to rise. The air inside the envelope of the balloon is heated, which makes it less dense and causes it to rise. As it rises, the cooler air outside the balloon displaces the heated air and keeps the balloon buoyant. So, option C is correct.
D. Air resistance refers to the force that opposes the motion of an object through the air. While air resistance can affect the overall flight of a hot air balloon, it is not the primary factor responsible for its initial rise. Therefore, option D is incorrect.
Therefore, the correct answer is C. Hot air balloons use convection to rise.