Name: June T.
Status: student
Age: 20s
Location: N/A
Country: N/A
Date: 7/14/2003
Question:
As a helium filled toy balloon ascends into the atmosphere, is the magnitude of its
velocity constant or is the
magnitude of its velocity increasing with altitude? Is the net lift force constant or increasing
with altitude?
Replies:
June -
I would expect that the vertical velocity of the balloon would decrease with altitude. The buoyant
force is a function of the difference between the density inside the balloon and that of the air
outside the balloon. This difference would decrease as the balloon expands until at some altitude
the two densities would be equal. At this altitude the balloon would cease rising.
It could also be the case that the balloon would expand to the point of bursting before the
pressures would become equal. I believe this is the system used with the weather balloons.
In this way, the radiosonde package drops back to earth.
The horizontal velocity of the balloon would generally increase with altitude and become more
easterly. This is due to the prevailing winds at this latitude.
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