A ray of light strikes a flat mirror at an angle of 40° from the perpendicular. The light is reflected at what opposite angle to the same perpendicular line?
a) 40°
b) 50°
c) 30°
d) 60°

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.

Determine the moment of the force f about an axis extending between a and c. express the result as a cartesian vector. a is at the origin, c is at (4,3,0) and f = (4i + 12j -3k) lb coming out of b (4,3,-2).

When you hold a rectangular object, how does the area of the side that is resting on your hand affect the pressure and the force that the object exerts?