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A police car's radar gun emits microwaves with a frequency of f1= 7.50 GHz. The beam reflects from a speeding car, which is moving toward the police car at 48.0m/s with respect to the police car. The speeder's radar detector detects the microwave at a frequency f2. a) Which is larger f1 or f2? b) Find the frequency difference f2- f1.

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Hubert Koch
Hubert KochLv2
6 Feb 2019
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Related textbook solutions

Physics: Principles with Applications
7th Edition, 2013
Giancoli
ISBN: 9780321625922

Related questions

Suppose that a police car on the highway is moving to the right at28 m/s, while a speeder is coming up from almost directly behind ata speed of 38 m/s, both speeds being with respect to the ground.The police officer aims a radar gun at the speeder. Assume that theelectromagnetic wave emitted by the radar gun has a frequency of7.00 109 Hz. Find the the difference between the frequency of thewave that returns to the police car after reflecting from thespeeder's car, and the original frequency emitted by the policecar.


This is what I have so far: (sqrt(3E8-10 - 10)/(3E8+10 + 10)) x 7E9

When a car with its horn blowing drives by an observer, the pitch of the horn seems higher as it approaches and lower as it recedes (see the figure). This phenomenon is called the Doppler effect. If the sound source is moving at speed relative to the observer and if the speed of sound is , then the perceived frequency f is related to the actual frequency   as follows:

 

We choose the minus sign if the source is moving toward the observer and the plus sign if it is moving away.
Suppose that a car drives at 110 ft/s past a woman standing on the shoulder of a highway, blowing its horn, which has a frequency of 500 Hz. Assume that the speed of sound is 1130 ft/s. 

(a) What are the frequencies of the sounds that the woman hears as the car approaches her and as it moves away from her?
(b) Let A be the amplitude of the sound. Find functions of the form

 

that model the perceived sound as the car approaches the woman and as it recedes.

 

 

A zoom lens system is a combination of lenses that produces a variable magnification of a fixed object as it maintains a fixed image position. The magnification is varied by moving one or more lenses along the axis. Multiple lenses are used in practice, but the effect of zooming in on an object can be demonstrated with a simple two-lens system. An object, two converging lenses, and a screen are mounted on an optical bench. Lens 1, which is to the right of the object, has a focal length of f1 of 5.00 cm, and lens 2, which is to the right of the first lens, has a focal length of f2 of 10.0 cm. The screen is to the right of lens 2. Initially, an object is situated at a distance of 7.50 cm to the left of lens 1, and the image formed on the screen has a magnification of +1.00.

(a) Find the distance between the object and the screen.

(b) Both lenses are now moved along their common axis while the object and the screen maintain fixed positions until the image formed on the screen has a magnification of +3.00. Find the displacement of each lens from its initial position in part (a).

(c) Can the lenses be displaced in more than one way?

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