# Simple question on Ratio of Kinetic to rest energy

#### MillerGenuine

1. The problem statement, all variables and given/known data

A pitcher can throw a baseball at 44 m/s. what is the ratio of kinetic energy to the rest energy E=mc^2. (can you use k=1/2mv^2 ?)

2. Relevant equations

rest energy=mc^2
K=gamma*mc^2 - mc^2
k=1/2mv^2

3. The attempt at a solution
Im just not sure how to go about this problem. It seems i can use k=1/2mv^2 because the velocity is well below c. From there i would take me kinetic energy and divide it by the rest enregy to get the ratio..??

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#### berkeman

Mentor
1. The problem statement, all variables and given/known data

A pitcher can throw a baseball at 44 m/s. what is the ratio of kinetic energy to the rest energy E=mc^2. (can you use k=1/2mv^2 ?)

2. Relevant equations

rest energy=mc^2
K=gamma*mc^2 - mc^2
k=1/2mv^2

3. The attempt at a solution
Im just not sure how to go about this problem. It seems i can use k=1/2mv^2 because the velocity is well below c. From there i would take me kinetic energy and divide it by the rest enregy to get the ratio..??
Yep. They just want to show how huge the rest energy is...

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