If a person drives 4 miles east, then 3 miles west, here are the facts:
They are 1 mile away from where they started.
They have driven a total of 7 miles.
Answer:

Explanation:
According to coulombs law force between two charges is given by
here R is the distance between both the charges which is given as 25 cm
We have given force F =0.036 N
So
As
is constant which value is 


The average electric current in the lightning will be 8 ×
A
<h3>
Why Lightning Conductors on top of a tower ?</h3>
The lightning conductors are long metal strips running from the spike end of a conductor on the top of a building to the earth. They are used to prevent buildings from destruction when struck by thunder or lightning.
Given that a lightning strike can transfer as much as electrons from the cloud to the ground. if the strike lasts 2ms, to calculate the average electric current in the lightning, we will first consider the charge released.
one charge = 1.6 ×
C
Average current I = Q/t
Where
- Q = charge = 1.6 ×
C
- t = time = 2ms = 2 ×
s
Substitute all the parameters into the formula
I = 1.6 ×
C ÷ 2 × 
I = 8 ×
A
Therefore, the average electric current in the lightning will be 8 ×
A
Learn more about Lightning here: brainly.com/question/3183045
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For a cylinder that has both ends open resonant frequency is given by the following formula:

Where n is the resonance node, v is the speed of sound in air and L is the length of a cylinder.
The fundamental frequency is simply the lowest resonant frequency.
We find it by plugging in n=1:

To find what harmonic has to be excited so that it resonates at f>20Hz we simply plug in f=20 Hz and find our n:

We can see that any resonant frequency is simply a multiple of a base frequency.
Let us find which harmonic resonates with the frequency 20 Hz:

Since n has to be an integer, final answer would be 323.