•• Your roommate is working on his bicycle and has the bike upside down. He spins the 60-cm-diameter wheel, and you notice that a pebble stuck in the tread goes by three times every second. What are the pebble’s speed and acceleration?

Explanation:

We have an uniform circular motion, therefore, the pebble’s speed is given by the distance traveled in a revolution and the period (T), since this is the time pebble’s takes to complete a revolution:

The period is inversely proportional to the frequency:

So, we have:

Recall that the radius is the half of the diameter and one revolution per is equal to one Hz:

The centripetal acceleration is defined as:

i guess it’s a and b