It’s also why car speedometers almost always read low. The indicated speed of the car is going to depend on tire circumference, which will vary with the precise tire, inflation, vehicle load, tread wear, temperature.
Car Manufacturers know this, and the don’t want the indicated speed to read lower than actual, so they calibrate them to read a touch high.
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You could fall off a cliff and die.
You could get lost and die.
You could hit a tree and die.
OR YOU COULD STAY HOME AND FALL OFF THE COUCH AND DIE.