Suppose 300 g of water at 50°C must be cooled to 40°C by adding cold water. The temperature of the cold water is 10°C. How much of the cold water must be added to the hot water to bring the temperature down to 40°C?

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.