Question

A baseball player can swing his bat at 120 mph. A baseball pitcher can throw a fastball at 80mph. When the baseball meets the bat in an elastic head-on collision, at what speed will the ball leave the bat? Assume that the mass of the ball is negligible compared to that of the bat. (Multiple Choice but show work)

a. 160 mph

b. 240 mph

c. 300 mph

d 320 mph

Answer 1

OPTION A) 160 mph is the right answer.

On applying conservation of momentum as well as conservation of energy we get the following equations,

where,

is the final velocity of the ball,

is the initial velocity of the ball,

is the final velocity of the bat,

is the initial velocity of the bat,

is the mass of the bat,

is the mass of the ball,

It is given therefore we can neglect

Therefore the first equation becomes,