Problem 1: A cylindrical storage tank has a cross sectional area A1=1.5 m2. The

Question

Problem 1: A cylindrical storage tank has a cross sectional area A1=1.5 m2. The tank is set up
vertically on the ground and filled with V=7.5 m3 of water. There is a tap at the bottom of the
tank with an internal cross sectional area of 1.5 cm2. How long does it take to fill a 240 mL cup
from the tap?

Problem 2: Two identical loud speakers emit sinusoidal spherical sound waves in phase at a frequency of
85Hz. The speed of sound is 340 m/s. The speakers are mounted at two adjacent corners (sharing a
common wall) of a square 10m x 10m room. A student walks along the wall opposite the speakers,
carefully monitoring the loudness of sound. How many times will the student experience destructive
interference (a sharp drop in loudness) walking over the entire length of that wall?

Explanation / Answer

1.
A1 = 1.5 m^2
V = 7.5 m^3
height of water in tank, h = V/A = 7.5/1.5 = 5 m

Velocity of flow of water,
v = sqrt (2*g*h)
    = sqrt (2*9.81*5)
    = 9.9 m/s
    = 990 cm/s

A2 = 1.5 cm^2

volume to be filled,V2 = 240 mL = 240 cm^3
A2*v =V/t
1.5*990 = 240/t
t = 0.16 s
Answer: 0.16 s

I am allowed to answer only 1 question at a time

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