What Is the Average Acceleration of a Baseball Hit by a Bat?

[Prototype44]

Homework Statement

Need assistance with this problem.

Homer Agin leads the Varsity team in home runs. In a recent game, Homer hit a 96 mi/hr sinking curve ball head on, sending it off his bat in the exact opposite direction at 56 mi/hr. The actually contact between ball and bat lasted for 0.75 milliseconds. Determine the magnitude of the average acceleration of the ball during the contact with the bat. Express your answer in both mi/hr/s and in m/s/s. (Given: 1.00 m/s = 2.24 mi/hr)

Vf=-56mi/hr Vi=96mi/hr
t=7.5×10^4s

Homework Equations

a=v÷t

The Attempt at a Solution

(-56-96)÷7.5×10^4=-2.03×10^-3mi/hr/s

The answer to the problem on the link http://www.physicsclassroom.com/calcpad/1dkin/prob8.cfm says 2.0 x 10^5 mi/hr/s for one of the answers.

 

[Villyer]

I think you simply plugged it in wrong, (-56-96)÷7.5×10^4 = 2.0 x 10^5