Why do the passengers on a high-flying airplane not appear weightless, similar to the astronauts on the space station?

Even in space, there is still presence of gravity. The cause of weightlessness is not how far above the earth the space shuttle is but rather how fast it is travelling. The shuttle is in free fall causing weightlessness, but it is travelling fast enough to miss the earth as it falls. Similarly, the airplane could also provide weightlessness if it went free fall as well. However, that ends as the plane hits the ground. 

answer: the answer is a

when heated, the valance electrons increased their speed and transferred the heat from electron to electron.   i just took the test.