I don’t know how air would be an insulator so I’m guessing that one isn’t
Answer:
Therefore the speed of q₂ is 1961.19 m/s when it is 0.200 m from from q₁.
Explanation:
Energy conservation law: In isolated system the amount of total energy remains constant.
The types of energy are
- Kinetic energy.
- Potential energy.
Kinetic energy 
Potential energy =
Here, q₁= +5.00×10⁻⁴C
q₂=-3.00×10⁻⁴C
d= distance = 4.00 m
V = velocity = 800 m/s
Total energy(E) =Kinetic energy+Potential energy
+ 

=(1280-337.5)J
=942.5 J
Total energy of a system remains constant.
Therefore,
E
+ 




m/s
Therefore the speed of q₂ is 1961.19 m/s when it is 0.200 m from from q₁.
Answer:

Explanation:
The resistance of a wire is given by:

where
is the resistivity of the material
L is the length of the wire
A is the cross-sectional area of the wire
1) The first wire has length L and cross-sectional area A. So, its resistance is:

2) The second wire has length twice the first one: 2L, and same thickness, A. So its resistance is

3) The third wire has length L (as the first one), but twice cross sectional area, 2A. So, its resistance is

By comparing the three expressions, we find

So, this is the ranking of the wire from most current (least resistance) to least current (most resistance).
You have to know what the temperature of your suroundings first and then you can melt it with the tools you need. yeah that's another thing know what tools you need and then be safe!:D