Question

Lightning quickly heats the air causing it to expand, which produces the sound of thunder.
Sound travels approximately $1$ mile in $5$ seconds. Knowing $X=r\cdot t$ (where $D=$ distance, $r=$ rate and $t=$ time), how far away is a thunderstrom when you notice a $3$-second delay between the flash of lightning and the sound of thunder?

• A. $1$ mile away
• B. $3/5$ mile away
• C. $1/2$ mile away
• D. $1/5$ mile away

Answer 1

The correct option is B $3/5$ mile away

Distance covered by sound $=1mile$

Time taken $=5s$

we now, $D=rt$ [Given]

$r=\frac{D}{t}$

Rate of sound $=\frac{1}{5}\frac{mile}{5}$

Time delay between flash of lightning

and sound of thunder $=3s$

Distance of thunderstrom from lighting

$=r\times t$

$=\frac{1}{5}\times 3$

$=\frac{3}{5}mile$