Where does the energy come from?

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A helium balloon rises due to the buoyant force acting on it, as helium is less dense than air. This buoyancy allows the balloon to float in the atmosphere, gaining kinetic energy as it ascends. As the balloon moves upward in the gravitational field, it also gains gravitational potential energy. The relationship between mass, velocity, and kinetic energy is defined by the equation KE = 1/2 mv². The discussion highlights the interplay between buoyancy and gravitational forces in the balloon's ascent.
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When a helium balloon soars into the sky, it gains KE and gravitational PE. where does that energy come from?
 
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Best answer I can think of is that the balloon is being acted on by a buoyant force. Helium is less dense than air, and so the average density of the balloon is less than that of air. The balloon therefore "floats" in this sea of air called the atmosphere, and the buoyant force causes it to rise. Any corrections/clarifications?
 
The lighter helium is bouyant in the denser air - the bouyant forces cause the helium balloon to rise with some velocity. Kinetic energy is simply 1/2 mv2.

The balloon is rising in the gravitational field, hence the mass of the balloon is gaining potential energy.
 
Thank you very much.
 
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