What is the frequency of a wave with an energy of (5.42x10^-19) J? Answer to 3 significant figures in scientific notation. Note: Your answer is assumed to be reduced to the highest power possible. Your Answer:

An astronomer measures the speed of recession of a remote galaxy to be 365 km/s using the Doppler principle According to the Hubble relation, about how far away is the galaxy?

An entrepreneur decides to invent and market a device that will fool the Doppler radar units used to detect cars that are speeding. The device would be placed at the very front of the car and would detect the radar signal, determine its frequency, and transmit back its own radar signal that would make the radar unit register a legal speed. What would the frequency of the "fake'' signal have 10 be in comparison to the original? If a second unit were designed to be placed at the back end of the car, what would be different about the frequency it would have to use compared to that used by the unit at the from?

You are working at an open-air amphitheater, where rock concerts occur regularly. The venue has powerful loudspeakers mounted on 10.6-m-tall columns at various locations surrounding the audience. The loudspeakers emit sound uniformly in all directions. There are ladder steps sticking out from the columns, to help workers service the loudspeakers. Many times, audience members break through the protective fencing around the columns and climb upward on the columns to get a better view of the performers. The upcoming concert is by a group that states that several very-high-volume pulses of sound occur in their concerts, and these sounds are part of their artistic expression. The amphitheater owners are worried about people climbing the columns and being too close to the loudspeakers when these peak sounds are emitted. They do not want to be held responsible for injuries to audience members ears. Based on past performances of the group, you determine that the peak sound level is 150 dB measured 20.0 cm from the speakers on the columns. The owners ask you to determine the heights on the columns at which to mount impassable barricades to keep people from getting too close to the speakers and hearing sound above the threshold of pain.

An ultrasonic tape measure uses frequencies above 20 MHz to determine dimensions of structures such as buildings. It does so by emitting a pulse of ultrasound into air and then measuring the time interval for an echo to return from a reflecting surface whose distance away is to be measured. The distance is displayed as a digital readout. For a tape measure that emits a pulse of ultrasound with a frequency of 22.0 MHz., (a) what is the distance to an object from which the echo pulse returns after 24.0 ms when the air temperature is 26C? (b) What should be the duration of the emitted pulse if it is to include ten cycles of the ultrasonic wave? (c) What is the spatial length of such a pulse?

A train sounds its horn as it approaches an intersection. The horn can just be heard at a level of 50 dB by an observer 10 km away, (a) What is the average power generated by the horn? (b) What intensity level of the horn's sound is observed by someone waiting at an intersection 50 in from (lie train? Treat the horn as a point source and neglect any absorption of sound by the air.

A student holds an inexpensive sonic range finder and uses the range finder to find the distance to the wall. The sonic range finder emits a sound wave. The sound wave reflects off the wall and returns to the range finder. The round trip takes 0.012 s. The range finder was calibrated for use at room temperature T=20C , but the temperature in the room is actually T=23C . Assuming that the timing mechanism is perfect, what percentage of error can the student expect due to the calibration?

A cowboy stands on horizontal ground between two parallel, vertical clifTs. He is not midway between the cliffs. Me fires a shot and hears its echoes. The second echo arrives 1.92 s after the first and 1.47 s before the third. Consider only the sound traveling parallel to the ground and reflecting from the cliffs, (a) What is the distance between the cliffs? (b) What If? If he can hear a fourth echo, how long after the third echo does it arrive?

A tuning fork generates sound waves with a frequency of 246 Hz. The waves travel in opposite directions along a hallway, are reflected by end walls, and return. The hallway is 47.0 m long and the tuning fork is located 14.0 m from one end. What is the phase difference between the reflected waves when they meet at the tuning fork? The speed of sound in air is 343 m/s.

Consider the following wave function in SI units: P(r,t)=(25.0r)sin(1.36r2030t) Explain how this wave function can apply to a wave radiating from a small source, with r being the radial distance from the center of the source to any point outside the source. Give the most detailed description of the wave that you can. Include answers to such questions as the following and give representative values for any quantities that can be evaluated. (a) Does the wave move more toward the right or the left? (b) As it moves away from the source, what happens to its amplitude? (c) Its speed? (d) Its frequency? (e) Its wavelength? (f) Its power? (g) Its intensity?