# Circular Motion Application Question

#### Tak Mok

1. Homework Statement
First problem: The speedometer in a car is driven by a cable connected to the shaft that turns the car's wheels. Will speedometer readings be more or less than actual speed when the car's whells are replaced with smaller ones?

Second problem: Keeping in mind the concpet from the previous question, a taxi driver wishes to increase his fares by adjusting the size of his tires. Should he change to larger tires or small tires?

2. Homework Equations
frequency = (number of rotations or revolutions)/(time in seconds)
speed,velocity = (distance in meters)/(time in seconds)

3. The Attempt at a Solution

For the first problem, I know that the smaller the wheel, the less the car travels per one revolution because the circumference is less.

I am not sure how this affects the speed though.

Could someone please explain this to me and how it relates to the second question.

Thank you very mich.

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#### haruspex

Homework Helper
Gold Member
2018 Award
I am not sure how this affects the speed though.
If the speedo is showing the same speed in two different tests, what can you about the shaft speeds in those tests?
If one test is with smaller wheels, what can you say about the road speeds?

"Circular Motion Application Question"

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