soil i think is this from apex?
Answer:
That happens to me a few times.
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<span>The reason that things look wavy in the heat over a hot grill or stove is that the air temperature is not stable. Hot air naturally rises, so as air comes off the hot surface, it rises for a bit before rapidly cooling and sinking to be heated again. This constant mixing of hot and cool air produces vibration. This vibration affects how we see the light moving through the air, making it look wavy.</span>
Answer:
<em>There must be added 500 cm3 of alcohol to bring the concentration to 80%.</em>
Explanation:
<u>Concentration</u>
The concentration of a solution is a measure of the amount of solute that has been dissolved in a given amount of solution.
In the container, there are 2 liters (2000 cubic centimeters) of a solution, 75% of which is alcohol (solute) and 25% of water (solvent).
The original amount of alcohol is:
H = 2000*75% = 1500 cc
The original amount of water is:
W = 2000*25% = 500 cc
When we add x cc of pure alcohol, there are 1500+x cc of alcohol out of 2000+x cc of solution.
The new concentration is calculated as:

And it's known this concentration is 80% (0.8), thus:

Multiplying by 2000+x:

Operating:

Rearranging:



x= 500
There must be added 500 cm3 of alcohol to bring the concentration to 80%
Answer:
<em>2 m/s</em>
<em></em>
Explanation:
The electromagnetic flow-metre work on the principle of electromagnetic induction. The induced voltage is given as

where
is the induced voltage = 2.88 mV = 2.88 x 10^-3 V
is the distance between the electrodes in this field which is equivalent to the diameter of the tube = 1.2 cm = 1.2 x 10^-2 m
is the velocity of the fluid through the field = ?
is the magnetic field = 0.120 T
substituting, we have
2.88 x 10^-3 = 0.120 x 1.2 x 10^-2 x 
2.88 x 10^-3 = 1.44 x 10^-3 x 
= 2.88/1.44 = <em>2 m/s</em>