Q:A hiker 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 2.0 after shouting. Estimate the length of the lake in meters. The speed of sound in air is 343 m/s.
Answer:
343 m.
Explanation:
Echo: This is the sound heard after the reflection of sound wave in a plane surface.
v = 2x/t.......................... Equation 1
Where v = speed of sound in air, x = length of the lake, t = time the echo was heard.
making x the subject of the equation,
x = vt/2....................... Equation 2
Given: v = 343 m/s, t = 2 s
Substitute into equation 2,
x = 343(2)/2
x = 343 m.
Hence the length of the lake in meters = 343 m.
Answer:
Generally, the lowest overtone for a pipe open at one end and closed would be at y / 4 where y represents lambda, the wavelength.
Since F (frequency) = c / y Speed/wavelength
F2 / F1 = y1 / y2 because c is the same in both cases
F2 = y1/y2 * F1
F2 = 3 F1 = 750 /sec
Note that L = y1 / 4 = 3 y2 / 4 for these wavelengths to fit in the pipe
and y1 = 3 y2
A spring that obeys Hooke's law has a spring force constant of 272 N/m. This spring is then stretched by 28.6 cm
The gravitational field strength on the moon is of the gravitational field strength on the earth
<u>On the earth:</u>
the gravitational field strength (g) is determined as:
where:
- G: the gravitational constant
- m: the mass of the earth
- r: the radius of the earth
<u>Then on the moon:</u>
*9.8=1.6 N/kg[/tex]
<u>The answer will be</u> : A.1.6 N/kg
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