Ahiker determines the length of a lake by listening for the echo of her shout reflected by a cliff at the far end of the lake. she hears the echo 2.9 s after shouting. the speed of sound in air is 343 m/s. determine the length of the lake.

497.35 m.

Explanation:

Echo: This is the sound heard after the reflection of sound wave on a plane surface.

v = 2x/t Equation 1

Where v = speed of sound in air, x = length of the lake, t = time taken to hear the echo.

Making x the subject of the equation,

x = vt/2 Equation 2

Given: v = 343 m/s, t = 2.9 s.

Substitute into equation 2

x = 343×2.9/2

x = 497.35 m

Thus the length of the lake  = 497.35 m.

f=ma a/f/m a= 480/60 a = 8m/s/s that is quick wow