During baseball practice, a batter hits a high flyball, and then runs in a straight line and catches it. which has the greater average velocity over the time interval between hit and catch?

The batter and the fly ball have the same average velocity, i.e. no individual velocity is greater than the other.

Explanation:

First of all, it is worthy of note that in a baseball game, when the batter hits the ball, he is expected to immediately make a run in an attempt to catch the ball, by so doing, the batter has a greater chance of catching the ball before it hits the ground  and this is exactly what the batter has done in this practice.

1. The fly ball is hit and the batter runs immediately , this means the batter and the fly ball have the same start time t.

2. The batter catches the fly ball after certain time i.e. the same end time.

3. The batter runs in a straight line to catch the ball i.e. the displacement of both batter and fly ball from hit point to catch point is the same.

MATHEMATICALLY

Where D = Displacement and t = time

Average velocity  

Where

and

This means

absorption lines are where light has been absorbed by the atom thus you see a dip in the spectrum whereas.

emission spectra have spikes in the spectra due to atoms releasing photons at those wavelengths.

explanation: