The mean life of an elementary particle pion is `2xx10^(-7)` ns. The age of the univers is about `4xx10^9` years. Identify a physically meaning time that is approximately half way between these two on a logarithmic scale.

Explanation

Here, `t_1 =2xx10^(-7) ns = 2xx10^(16)s`
`t_2 =4xx10^9 years = 4xx10^9xx3xx10^7s`
`1.2xx10^(17)s`
Let the time interval t be half way between `t_1`
and `t_2` on logarithmic scale.
`:. Log t= (1)/(2) [ log t_1 + log t_2]`
`(1)/(2) [ log 10^(16) +log 10^(17)]`
` =(1)/(2)(-16 + 17) = 0.5 ~= 1`
`:. t =10s`
This is the time taken by an athlete to run a
100 metre track.