Two fire trucks are moving toward each other at a rate of 25m/s. If the first fire truck emits a frequency of 10000Hz and the ambient temperature is 40 degree celsius, what will be the observed frequency of the second fire truck.

A train on a straight track sounds a 400 Hz horn when passing a parked car on the road. The train is moving at 20 m/s and the temperature is 10°C. Find the apparent frequency of the horn for a person sitting inside the car when the train is approaching and when the train is moving away.

In general, X-rays have wavelengths between 10 nm and 0.01 nm. For an X-ray with a wavelength of 1 nm, what is the corresponding frequency? The speed of light is 3 × 108 m/s.  The frequency of the X-ray is _____ × 1016 Hz

Police radar determines the speed of motor vehicles using the same Doppler-shift technique employed for ultrasound in medical diagnostics. Beats are produced by mixing the double Doppler-shifted echo with the original frequency. If 1.25 × 109 Hz microwaves are used and a beat frequency of 163 Hz is produced, what is the speed of the vehicle in m/s? (Assume the same Doppler-shift formulas are valid with the speed of sound replaced by the speed of light.)

You place your ear onto a steel railroad track and hear the sound of a distant train through the rails Δt = 2.7 seconds before you do through the air. The speed of sound in steel is vs = 6100 m/s, and and the air temperature is 36° C. Find the distance, D, to the train in meters.

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The wavelength of light visible to the human eye is on the order of 6 × 10 −7 m. If the speed of light in air is 3 × 10 8 m/s, find the frequency of the lightwave.

In a student lab exercise, the wavelength of a 44,418Hz ultrasound wave is measured to be 0.812cm. Find the air temperature. Answer in K   Calculate to one decimal.

1. (a) What is the intensity in w/m of a laser beam used to burn away cancerous tissue that, when 90.0% absorbed, puts 540 J of energy into a circular spot 2.2 mm in diameter in 1.5 s? Hint: The laser is a collimated beam of light and does not produce a spherical wave. w/m? (b) Reflect on how this intensity compares to the average intensity of sunlight (about 1W/m) and the implications that would have if the laser beam entered your eye. Note how your answer depends on the time duration of the exposure. The intensity of a laser is about damaging if they enter your eye. times that of the sun, so clearly lasers can be very

2. A hiker shouts and hears the echo reflected from a cliff wall 3.80 s later. If the air temperature is 20°C, how far is the hiker from the cliff? (Assume no wind.) m 2 W S X H 2 113 mand 3 E D . с $ 4 R F % 5 V T G 6 MacBook Pro B Y H 9 N U 00. 8 J I M ( 0. 9 K C O - V I дв H .C O L P command ill > **** x { E option