Suppose a car's standard tires are replaced with tires `1.50` times larger in diameter. Will the car's speedometer reading be.

Options

A. 2.25 times too high
B. 1.50 times too high
C. 1.50 times too low
D. 2.25 times too low

Answer

D

Explanation

( c) The speedometer measuresthe number of revolutions per second of the tires. A larger tire will rotate fewer times to cover the same distance. The speedometer reading is assumed proportional to the rotation rate of the tires, `omega = v//R`, for a standard tire radius `R`, but the actual reading is `omega = v//(1.5) R`, or `1.5` times smaller. Example : When the car travels at `15 km//h`, the speedometer reads `10 km//h`.