Ella had a beaker of warm water. Its temperature was 70 celsius. She poured in some cold water and stirred the mixture. When she measured the temperature of the water, it had fallen to 40 celsius. Ella said "a lot of energy in the hot water has disapeared." Explain why Ella's statement is wrong.

Starting with only the balmer series light (visible light), how could we ensure that the solar panels generate a current that mark can use for his power station? a)by gradually increasing the brightness (amount) of light that we shine on it. b)by gradually increasing the frequency of the light we shine on it. c)by gradually increasing the wavelength of the light that we shine on it.

Which graph represents motion with an object with positive velocity that is located at a position of 3 meters at a time of 0 seconds? a) a b) bb eliminate c) c d) d

Why do astronauts in the space shuttle weigh less?