Simple machines, such as pulleys, levers, and gears, are never 100 percent efficient. This means that the energy you put into them is always greater than the useful energy you get out of them. Why is this

If a balloon is taken outside on a very cold day, what will occur?

What distance does a car travel as its speed changes from 0 to 20 m/s in 17 s at constant acceleration?

Aprisoner is forced to go into one of three rooms, but he can choose which room. the first room is ablaze with fire. the second one is rigged with explosives that will go off as soon as he enters. the third contains a pair of lions who haven't eaten in years. which room should he choose to survive?