# College Physics Problem 1.30

## Solution:

We are looking for generations passed in history. The general assumptions are:

• There are 1011 seconds in 1 history
• In 1 generation, there is 1/3 of a lifetime.
• In half a lifetime, there are 109 seconds

Therefore, the number of generations passed is

$\displaystyle 1history=1\:history\times \frac{10^{11}\:sec}{1\:history}\times \frac{1\:generation}{\frac{1}{3}\:lifetime}\times \frac{0.5\:lifetime}{10^9\:sec}$

$\displaystyle 1history=150\:generations$          ☚