Part A Your roommate is working on his bicycle and has the bike upside down. He spins the 56.0 cm - diameter wheel, and you notice that a pebble stuck in the tread goes by three times every second. What is the pebble's speed? Express your answer with the appropriate units. HA ? Value Units Submit Request Answer Part B What is the pebble's acceleration? Express your answer with the appropriate units. ? Value Units Submit Request