Arock, which weighs 1400 n in air, has an apparent weight of 900 n when submerged in fresh water (998 kg/m3). the volume of the rock is:

What is the frequency of a light wave with a wavelength of 620nm

Acoal-fired plant generates 600 mw of electric power. the plant uses 4.8 x 10^6 kg of coal each day, and the heat of combustion of coal is 3.3x 10^7 j/kg. the steam that drives the turbines is at a temperature of 300° c, and the exhaust water is at 37° c. (a) what is the overall efficiency of the plant for generating electric power? (b) how much thermal energy is exhausted each day? (c) what is the change in entropy of the universe for this heat engine? (d) using the same heat reservoirs, what is the maximum possible (carnot) efficiency for a heat engine?

The material that keeps its new shape after it is stretched is called?