Does anybody know the answer to this physics problem?

[darealprince]

Homework Statement

Ive have tried it so many times but can't get the right answer but the problem is: Your roommate is working on his bicycle and has the bike upside down. He spins the 54.0 cm-diameter wheel, and you notice that a pebble stuck in the tread goes by three times every second. What is the particles speed? and then what is the particles acceleration?

Homework Equations

The Attempt at a Solution

 

[danago]

How have you attempted this problem? If it goes by 3 times every second, how much distance is it covering in 1 second?

 

[darealprince]

Yes, but after a couple of different attempts, i finally got the answer, it turns out my rounding was off by a couple of digits. But thanks anyways