Answer: Ok, first lest see out problem.
It says it's a Long cylindrical charge distribution, So you can ignore the border effects on the ends of the cylinder.
Also by the gauss law we know that E¨*2*pi*r*L = Q/ε0
where Q is the total charge inside our gaussian surface, that will be a cylinder of radius r and heaight L.
So Q= rho*volume= pi*r*r*L*rho
so replacing : E = (1/2)*r*rho/ε0
you may ask, ¿why dont use R on the solution?
since you are calculating the field inside the cylinder, and the charge density is uniform inside of it, you don't see the charge that is outside, and in your calculation actuali doesn't matter how much charge is outside your gaussian surface, so R does not have an effect on the calculation.
R would matter if in the problem they give you the total charge of the cylinder, so when you only have the charge of a smaller r radius cylinder, you will have a relation between r and R that describes how much charge density you are enclosing.
One is bigger than the other and they are the same shape
The correct answer is A. Charged particles from the sun exite the atmosphere near the poles to create auroras.
Answer:
Centripetal acceleration,

Explanation:
Centripetal acceleration:
Centripetal acceleration is the idea that any object moving in a circle, in something called circular motion, will have an acceleration vector pointed towards the center of that circle.
Centripetal means towards the center.
Examples of centripetal acceleration (acceleration pointing towards the center of rotation) include such situations as cars moving on the cicular part of the road.
An acceleration is a change in velocity.
Formula for Centripetal acceleration:

Given here,
Velocity = 4.5 m/s
radius = 7.7 m
To Find :

Solution:
We have,

Substituting given value in it we get

Centripetal acceleration,
