matter expands when heated and contracts when cooled

I'll make it even easier for you . . . i only want one answer from you. Explain why the people here should do your homework for you.

You can say that its a steam train that goes through a coal powerplant =)

Always twist anoying homework questions to your favor as much as possible.

Imagine you live in Boston , where nothing is unusual. For instance, the other day, a young female with pink hair was on the Red Line subway, when all of a sudden she noticed that her pet snake had suddenly vanished.

She and the other passengers searched high and low. But could not find the snake. By the way, allowing a snake to accompany you on the subway is within your rights as a train passenger, here in Boston.

The 2nd interesting example is that of the female, who was standing on the subway train as it traversed along it's route in the Boston area. The female , so they say, wasn't aware of her pregnancy ( close to 9 months) and was standing up, looking through the door of the moving train, when all of sudden, she felt something gushing from her lower body.

She had sudenly given birth, much to her own surprise as well as the shock of her fellow passengers.

So much expansion and contraction, when one rides the Red Line in Boston.