9. the bottle and cup look empty, but they are not. explain why.
physical science
10. what is the original source of energy used to turn a water wheel? !
11. soon after a burning candle is covered with an upside down glass, the flame goes out. why?

Which of the following correctly describes what happens when an atomic bomb explodes? small pieces of fissionable material are joined and form a body with a mass greater than the critical mass, the relative number of neutrons escaping decreases, and a chain reaction and explosion result. large pieces of fissionable matter are brought together quickly and form a body with a mass smaller than the critical mass, the relative number of escaping neutrons increases, and a chain reaction and explosion result.