"A train is travelling on a straight horizontal track. A student on the train attaches a mass on a string to the ceiling of the train. The student observes that the mass remains stationary in the position shown."
http://www.clickpotato.com/movie/blade-runner/MibILI8ZKmL-G_8f
There's many link which you could click on. Hmm but i'm not sure if downloading would be free, but u can stream it!