robbie is swinging his favorite yo-yo in circles on a meter- long string. his classmate, lucy measures the instantaneous of the yo-yo as 12m/s what is the centripetal acceleration of the yo-yo ?

The stopwatch used by a student to measure velocity of a pulse in a slinky was of least count 0.1 second. he stops the stopwatch when a pulse has made 3 journeys from one end to the other of the slinky. he finds the seconds hand to be at 52nd division. calculate the correct time noted by him.