3 456
12
A bat chasing a moth emits a sequence of three chirps every 0.010 seconds and
later hears the echos of the chirps as detailed in the diagram below.
Click!
Click!
Click!
Echo!
Echo! Echo!
++
0.09s
Time:
Os 0.01s 0.02s
0.095s 0.10s
Question: How far away is the moth when the bat hears the third echo?
Make sure to explain how you arrived at your answer.

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.

Electric field of the earth. the earth has a net electric charge that causes a field at points near its surface equal to 150 n> c and directed in toward the center of the earth. (a) what magnitude and sign of charge would a 60-kg human have to acquire to overcome his or her weight by the force exerted by the earth’s electric field? (b) what would be the force of repulsion between two people each with the charge calculated in part (a) and separated by a distance of 100 m? is use of the earth’s electric field a feasible means of flight? why or why not?

Why do astronauts in the space shuttle weigh less?