Two loudspeakers are about 10 m apart in the front of a large classroom. if either speaker plays a pure tone at a single frequency of 400 hz, the loudness seems pretty even as you wander around the room, and gradually decreases in volume as you move farther from the speaker. if both speakers then play the same tone together, what do you hear as you wander around the room? a. the sound is louder but maintains the same relative spatial pattern of gradually decreasing volume as you move away from the speakers. b. the pitch of the sound increases to 800 hz, and the sound is louder but not twice as loud. it is louder closer to the speakers and gradually decreases as you move away from the speakers−except near the back wall, where a slight echo makes the sound louder. c. as you move around the room, some areas seem to be dead spots with very little sound, whereas other spots seem to be louder than with only one speaker. d. the sound is twice as loud−so loud that you cannot hear any difference as you move around the room. e. at points equidistant from both speakers, the sound is twice as loud. in the rest of the room, the sound is the same as if a single speaker were playing.

In a steady-flow steam power plant system, two adiabatic high-pressure and low-pressure turbines ane used to generate power. superheated steam enters the high-pressure turbine at 8 mpa and 550°c. the steam expands in the high-pressure turbine to a saturated vapor at 3 mpa. in order to increase the powe generation of the power plant, another steam turbine working in a lower pressure ranges is deployed. the outlet vapor from the first turbine is heated up at a boiler to the temperature of 500 c at the constant pressure of first turbine's outlet (3 mpa). then, the vapor enters the second turbine and produces extra work. the exit conditions of the second turbine are 5o kpa and 90 percent quality. if the total power output of the power plant is 25 mw, determine a) the mass flow rate of the water (kg/s). b) heat transfer rate in the boiler (mw). (30 points) 3 mpa 00 c 8 mpa s0 c high pres turbine low pres boiler turbine 50 kpa 3 mpa 09 saturated vapor t heat engine, shown in the figure, operates between high temperature and low temperature of through a heat 4. a carnot tn and tu respectively. this heat engine receives energy from a heat reservoir at t exchanger where the heat transferred is proportional to the temperature difference as ? = k (z,-7, ). it rejects heat at a given low temperature tl. to design the heat engine for maximum work output, find the high temperature, th, as a function of tes and t. (15 points) qe

An insulated 40 ft^3 rigid tank contains air at 50 psia and 120°f. a valve connected to the tank is now opened, and air is allowed to escape until the pressure inside drops to 25 psia. the air temperature during this process is kept constant by an electric resistance heater placed in the tank. determine the electrical work done during this process.

During a car accident, a 125kg driver is moving at 31m/s and in 1.5s is brought to rest by an inflating air bag. what is the magnitude of the change in momentum to the driver