A pitcher can throw a baseball at about 90 miles/hour (about 39.6 m/s). What is the ratio of the kinetic energy to the rest energy mc2? (Can you use K approximately equals 1/2mv2?)

Explanation:

The rest energy is the energy associated with the base ball at zero velocity which is expressed as

Note: the speed C is the speed of light which is expressed as 3*10^8

while the kinetic energy is the energy associated with the ball during its motion and is expressed as

the ratio can be expressed as

one "light year" is the distance that light travels, through vacuum, in one julian year.   that's 365.25 days, of 24 hours each.