The correct choice is
D. 22 Hz and 42 Hz.
In fact, the beat frequency is given by the difference between the frequencies of the two waves:

In this problem, the beat frequency is
, therefore the only pair of frequencies that gives a difference equal to 20 Hz is
D. 22 Hz and 42 Hz.
Answer:

Explanation:
The change in potential energy can be expressed as:

where K is a constant with a value of
, q1 and q2 are the charges of the proton and the electron and r is the distance between them.
The charge for the proton is
and the charge for the electron is
.
Converting r=1.0nm to m:

Replacing values:


Decibel - the decibel is a relative unit of measurement equal to one 10th of a bel
Let t = Theta and p = Phi
Tan t = y/x Then x =y/Tant.
Tant = y/(x-d) x-d = y/Tanp
y/Tant - d = y/Tanp
y -d*Tanr = y*Tant/Tanp
y-y*Tant/Tanp = d*Tanr
y(1 - Tanr/Tanp = d*Tant
y = d*Tant/(1-Tant/Tanp)
Answer:
power requirement is 23.52 ×
W
Explanation:
given data
flow rate q = 2 m³/s
elevation h = 1200 m
density of the water ρ = 1000 kg/m³
to find out
power requirement
solution
we will get power by the power equation that is
power = ρ× Q× g× h ...................1
put here all value we get power
power = ρ× Q× g× h
power = 1000 × 2 × 9.8 × 1200
power = 23.52 ×
so power requirement is 23.52 ×
W