Assuming no change in temperature,as a freely expanding helium-filled balloon rises in the atmosphere,the buoyant force that acts on it
A)increases.
B)decreases.
C)remains nearly the same for a long way.

Question

Quizplus · Accepted Answer

As the balloon rises, the air density decreases, so the buoyant force decreases. However, the balloon also expands, which increases the volume of air displaced, so the buoyant force increases. These two effects cancel each other out, so the buoyant force remains nearly the same for a long way.

Assuming No Change in Temperature,as a Freely Expanding Helium-Filled Balloon