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:
D. Pauli's exclusion principle
Explanation:
<em>A. Newton's laws</em> are related to the motion, they state that "Every object in a state of uniform motion will remain in that state of motion unless an external force acts on it", " Force equals mass times acceleration." and " For every action there is an equal and opposite reaction"
<em>B. Bohr's law </em>depicts an atom as a small, positively charged nucleus surrounded by electrons. These electrons travel in circular orbits around the nucleus.
<em>C. Aufbau principle</em>, also called the building-up principle or the aufbau rule, states that in the ground state of an atom or ion, electrons fill atomic orbitals of the lowest available energy levels before occupying higher levels
<em>D. Pauli's exclusion principle</em> states that <em>no two fermions (e.g., electrons) in an atom can have the same set of quantum numbers,</em> hence they have to "pile up" or "build up" into higher energy levels.
I hope you find this information useful and interesting! Good luck!
Answer:
<h2>21 N</h2>
Explanation:
The force acting on an object given it's mass and acceleration can be found by using the formula
force = mass × acceleration
From the question we have
force = 3.5 × 6
We have the final answer as
<h3>21 N</h3>
Hope this helps you
Conductivity is the property of matter in which a substance can transfer heat or electricity
