Uniform Circular Motion of a tire

[Muneerah]

Homework Statement

A point on the outer rim of a tire on a moving
vehicle exhibits uniform circular motion with
a frequency of 28 Hz. The diameter of the tire
is 40 cm.
How fast is the car moving?
Answer in units of km/hr.

Homework Equations

V=2 pi r f

The Attempt at a Solution

The first thing I did was finding the frequency in terms of hrs, and I got 100800 revelotions per hr. Then I found converted the radius to km so I got .0002 km. Then I found the velocity which is, 2 pi r f = 126.669 km/hr. My answer is wrong, I don't know what it is that I did wrong so if you can please help. Thank you

 

[xcvxcvvc]

Homework Statement

A point on the outer rim of a tire on a moving
vehicle exhibits uniform circular motion with
a frequency of 28 Hz. The diameter of the tire
is 40 cm.
How fast is the car moving?
Answer in units of km/hr.

Homework Equations

V=2 pi r f

The Attempt at a Solution

The first thing I did was finding the frequency in terms of hrs, and I got 100800 revelotions per hr. Then I found converted the radius to km so I got .0002 km. Then I found the velocity which is, 2 pi r f = 126.669 km/hr. My answer is wrong, I don't know what it is that I did wrong so if you can please help. Thank you

I'm getting the same answer. If I had to guess, your book/teacher probably miscalculated or had a typo.