Apositively-charged object with a mass of 0.129 kg oscillates at the end of a spring, generating elf (extremely low frequency) radio waves that have a wavelength of 3.86 × 10^7 m. the frequency of these radio waves is the same as the frequency at which the object oscillates. what is the spring constant of the spring?

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.