Law enforcement officers use radar guns based on the Doppler effect to measure the speed of automobiles. Explain why the details of the Doppler effect make it desirable for the officers to park near the road in a place without curves
What will be an ideal response?
The Doppler effect uses a measured change in the wavelength of photons to determine the speed of an object. The effect is only able to detect motion toward or away from the receiver, not motion directed side to side.
If the officer positioned himself far from the roadway, he would be viewing an oncoming car from an angle. In this situation, part of the velocity of the automobile would be side-to-side across the officer's line of sight. The Doppler effect would measure only the velocity of the car along the line of sight, and underestimate the true speed of the car. If the road was curved, the same situation would apply.
The officer can only get a true measure of the car's velocity if the velocity of the car is directly along the line of sight.
You might also like to view...
Consider a system consisting of two Einstein solids P and Q in thermal contact. Assume that we know the number of atoms in each solid and ?. What do we know about the system if we also know the quantum state of each atom in each solid?
A. Its macrostate B. Its microstate C. Its macropartition D. Its microstate and macropartition E. Its macrostate and macropartition F. Its macrostate and microstate T. Its macrostate, microstate, and macropartition
A solid wooden door, 90 cm wide by 2.0 m tall, has a mass of 35 kg. It is open and at rest. A small 500-g ball is thrown perpendicular to the door with a speed of 20 m/s and hits the door 60 cm from the hinged side, causing it to begin turning
The ball rebounds along the same line with a speed of 16.0 m/s relative to the ground. How much mechanical energy is converted to internal energy during this collision? A) 30 J B) 16 J C) 15 J D) 13 J E) 4.8 J
The Sun is a spherically shaped star that is
composed primarily of a)iron. b)hydrogen. c)water. d)helium.
As a given thundercloud's base elevation gets lower and lower, the possibility of lightning strike
A. is less, since the electric field gets weaker. B. is greater, because the electric field strength increases. C. is unchanged, because the thundercloud has not polarized.