It's just in the name! Accurate data is helpful, and correct, but reproducible data is all of that, and is able to be given to other people through different sources! At least, that's what my understanding of them are. Hope it helps!
Answer:
The charge density in the system is 
Explanation:
To solve this problem it is necessary to keep in mind the concepts related to current and voltage through the density of electrons in a given area, considering their respective charge.
Our data given correspond to:

We need to asume here the number of free electrons in a copper conductor, at which is generally of 
The equation to find the current is

Where
I =Current
V=Velocity
A = Cross-Section Area
e= Charge for a electron
n= Number of free electrons
Then replacing,


Now to find the linear charge density, we know that

Where:
I: current intensity
Q: total electric charges
t: time in which electrical charges circulate through the conductor
And also that the velocity is given in proportion with length and time,

The charge density is defined as

Replacing our values


Therefore the charge density in the system is 
Answer:
e) True Yes both are constant
Explanation:
Let us propose the solution of the problem before reviewing the statements, we use Newton's second law
F - fr = m a
N- W = 0
N = mg
The equation for the force of friction is
fr = μ N
F - μ mg = m a
F = m (a- μ g)
Now let's review the claims
.a) False. Normal force and friction are constants.
.b) False. Both are constant.
.c) False. Both are constant.
d.) False
e) True Yes both are constant
You're a little late. But if you want some short, quick rules, then these are
a couple that I would take in with me (stored only in my brain, of course):
-- If something is not accelerating or moving at all, then all the forces on it
must add up to zero. That could even mean a hanging rope.
-- In a vertical rope, the tension in it is the same everywhere in the rope.
The tension is the weight of whatever is hanging from the bottom.
That's really all I'm sure of, based on your hazy, fuzzy description of
what you've been doing in class. I don't want to get into things that
you might not have learned yet, and confuse you.