The expected time period between the observations of lightning and thunder would be 22.5 s.
How to calculate the time of sound waves?
The time taken by sound to reach a certain position can be calculated by the speed formula,
[tex]S = \dfrac dt[/tex]
Where,
[tex]S[/tex] - speed = 0.343 km/s
[tex]d[/tex] - distance = 7.5 km
[tex]t[/tex] - time = ?
Put the values in the formula,
[tex]0.343 = \dfrac {7.5} t\\\\t = \dfrac {0.343}{7.5}\\\\t = 22.5[/tex]
Therefore, the expected time period between the observations of lightning and thunder would be 22.5 s.
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