Sound level at distance of 15 m is given as 20 dB
so intensity at this distance is given as



now if we move closer to some some distance the sound level is now 50 dB
now the intensity is given as



now we know that



so now the distance from friend must be 47 cm
Answer:
the glucose in air will solidify and it will stop the process.
it will cause hot air
Answer:6.298,4.1,1.9015
Explanation:
Wavelength=
=
=4.397 m
Distance of 3rd speaker from speaker A is x
From B 78-x
Difference between the distances must be a whole number of wavelengths
First
for 1 st wavelength
2x=8.2+4.397=12.597
x=6.298m
second
For zero wavelength

2x=8.2
x=4.1m
Third

x=1.9015 m
29.213 cm3
First, calculate the mass of the water used. You do this by subtracting the original mass of the flask from the combined mass of the water and flask, giving:60.735 g - 31.601 g = 29.134 g
So we now know we have 29.134 g of water. To calculate the volume of the flask, simply divide by the density of the water, giving:29.134 g / (0.9973 g/cm3) = 29.213 cm3