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A physicist talks his way out of a traffic ticket.
He wrote a short physics paper to prove that the traffic cop couldn't really tell if he stopped at the stop sign. An excerpt from the article:
...
Here's the abstract. If you were a busy judge, who'd studied law more intently than mathematics in school, how would you react to it?
"We show that if a car stops at a stop sign, an observer, e.g., a police officer, located at a certain distance perpendicular to the car trajectory, must have an illusion that the car does not stop, if the following three conditions are satisfied: (1) the observer measures not the linear but angular speed of the car; (2) the car decelerates and subsequently accelerates relatively fast; and (3) there is a short-time obstruction of the observer's view of the car by an external object, e.g., another car, at the moment when both cars are near the stop sign."
The paper is four pages of dense reading, filled with equations and graphs, but here's the simple version:
Krioukov argues the officer, watching at an angle about 100 feet away, confused the car's actual (or linear) speed with its angular speed -- the rate at which it seemed to go by. If you'd like an analogy, think of yourself on a railroad platform as the express roars past. As the train approaches in the distance, it doesn't seem to move much, but as it passes you -- going no faster -- it certainly seems to race by.
...
Here's the abstract. If you were a busy judge, who'd studied law more intently than mathematics in school, how would you react to it?
"We show that if a car stops at a stop sign, an observer, e.g., a police officer, located at a certain distance perpendicular to the car trajectory, must have an illusion that the car does not stop, if the following three conditions are satisfied: (1) the observer measures not the linear but angular speed of the car; (2) the car decelerates and subsequently accelerates relatively fast; and (3) there is a short-time obstruction of the observer's view of the car by an external object, e.g., another car, at the moment when both cars are near the stop sign."
The paper is four pages of dense reading, filled with equations and graphs, but here's the simple version:
Krioukov argues the officer, watching at an angle about 100 feet away, confused the car's actual (or linear) speed with its angular speed -- the rate at which it seemed to go by. If you'd like an analogy, think of yourself on a railroad platform as the express roars past. As the train approaches in the distance, it doesn't seem to move much, but as it passes you -- going no faster -- it certainly seems to race by.
...
8 replies
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