The gas would also decrease in size since the container lost gas to decrease the size of the container.
C. unbalanced is the correct answer for newton's first law.
There's not enough information to find an answer.
I think the idea here is that in descending (416 - 278) = 138 meters,
the glider gives up some gravitational potential energy, which
becomes kinetic energy at the lower altitude. This is all well and
good, but we can't calculate the difference in potential energy
without knowing the mass of the glider.
Light is a form of energy.
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