If a wave has a frequency of 50 Hz and a wavelength of 3 meters, what is its Velocity? (Use
Formula)

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.

The researcher who studied the ability of cats to learn to escape from puzzle boxes was

He acceleration due to gravity on the surface of mars is about one third the acceleration due to gravity on earth’s surface. the weight of a space probe on the surface of mars is about