Hamish is studying what happens when he sends a sound wave through different mediums, and he records his data in a table.
which statement could made about the data collected in hamish’s table?
a. wave 1 will move the fastest.
b. wave 2 will move the slowest.
c. wave 3 will move the slowest.
d. wave 4 will move the fastest

Air is to be preheated by hot exhaust gases in a cross-flow heat exchanger before it enters the furnace. air enters the heat exchanger at 95 kpa and 20°c at a rate of 0.6 m^3/s. the combustion gases (cp = 1.10 kj/kg°c) enter at 160°c at a rate of 0.95 kg/s and leave at 95°c. determine the rate of heat transfer to the air and its outlet temperature.

Carbon is allowed to diffuse through a steel plate 15 mm thick. the concentrations of carbon at the two faces are 0.65 and 0.30 kg c/m^3 fe, which are maintained constant. if the preexponential and activation energy are 6.2 x 10-7 m2 /s and 80,000 j/mol, respectively, compute the temperature at which the diffusion flux is 1.43 x 10^-9 kg/m^2 -s.

If the chemical properties of a substance remain unchanged and appearance or shape of a substance changes it is called a ?