A father fashions a swing for his children out of a long rope that he fastens to the limb of a tall tree. As one of the children swings from this rope that is 6.00 m long, his tangential speed at the bottom of the swing is 7.50 m/s. What is the centripetal acceleration, in m/s2, of the child at the bottom of the swing?

An ultracentrifuge accelerates uniformly from rest to 100,000 rpm in 2.0 min. If this ultracentrifuge accelerates 4.0 seconds starting from rest, what is the magnitude of the centripetal acceleration in unit of gravitational acceleration g for your sample sitting at 4.0 cm from the center axis? Use g = 9.8 m/s2. Hint: compute the centripetal acceleration in unit of m/s2 first, then divided by g will be your answer. For example, if your centripetal acceleration is 19.6 m/s2, your answer measured in unit of g is 2.0.

QUESTION 5 A windmill-style softball pitcher executes a pitch in 0.5s. If her pitching arm is 1m long, what is the magnitude of the radial acceleration on the ball just before the ball release, when tangential ball speed is 20 m/s?
 100 m/s2 200 m/s2 300 m/s2 400 m/2 


 QUESTION 6 A windmill-style softball pitcher executes a pitch in 0.5s. If her pitching arm is 1m long, what is the magnitude of the total acceleration on the ball just before the ball release, when tangential ball speed is 20 m/s?
 401.9 m/s2 378.9 m/s2 289 m/s2 479 m/s2

A maintenance man is twirling a set of keys on the end of a lanyard. If the keys have a centripetal acceleration of 145 m/s² and the lanyard is .15 meters long, what is the tangential speed of the keys? 12.