Measuring Speed of Objects as They Approach You

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It is possible to determine the speed of an approaching object, such as a car, from a stationary position. One method involves timing how long it takes the vehicle to travel between two known points, like lamp posts, and calculating speed based on that distance and time. The accuracy of this measurement depends on the precision of the time measurement, with shadows cast by the vehicle potentially aiding in accuracy. Additionally, concepts like the Doppler effect and police radar technology are relevant in measuring speed. Overall, accurate speed measurement is feasible with the right techniques and tools.
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As a stationary object, is it possible to determine the speed of an object as it approaches you? If so, how? ...and with accuracy?

For instance, if I'm standing on the sidewalk, can I determine the speed of a car on the road as it approaches me?
 
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Physics Novice said:
As a stationary object, is it possible to determine the speed of an object as it approaches you? If so, how? ...and with accuracy?

For instance, if I'm standing on the sidewalk, can I determine the speed of a car on the road as it approaches me?

Sure. Around here the traffic police use hand-held radar guns to catch speeders.
 
Time how long it takes the car to cover the distance between two objects (eg two lamp posts). Later measure the distance between the two lamp posts. Calculate the speed. The accuracy will be limited to how accurately you can measure the time. If the car casts a shadow on the lamp posts as it passes I'd suggest you can get quite an accurate measurement.
 
Physics Novice said:
As a stationary object, is it possible to determine the speed of an object as it approaches you? If so, how? ...and with accuracy?

Some pictures and info to go along with Nugatory's reply: Doppler effect, Police RADAR.
 

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