A baseball is hit with a bat and, as a result, its direction is completely reversed and its speed is doubled. If the actual contact with the bat lasts 0.45 s, what is the ratio of the magnitude of the average acceleration of the ball to its original speed

6.7 / s.

Step-by-step explanation:

Initial velocity = u m/s

From the question, final velocity, v = - 2u m/s

Note - (the minus sign indicates that the direction was reversed and doubled)

t = 0.45

From equation of motion,

v = u + at

Acceleration, a = (v - u) / t

= (-2u - u) / 0.45

= - 3u/0.45

Acceleration, a/Original speed, u = 3/0.45

= 6.7 / s