Answer:
When one of charge is doubled, the magnitude of the force between them gets doubled.
Explanation:
The electric force between two electric charges is given by :
Here,
k is the electrostatic force
d is the separation between charges
are charges
If one of the charges is doubled in magnitude while maintaining the same separation between the charges, 
New force becomes,
When one of charge is doubled, the magnitude of the force between them gets doubled. Hence, this is the required solution.
You skipped over a number in the question, and you didn't tell me what my average speed is. Lucky for you, my average speed has NO EFFECT on the answer to the question.
When you calculate velocity, you only use the straight-line distance between the start-point and the end-point. It doesn't matter what route the thing took to get there, or how much ground it actually covered.
If I travel in a circle and stop at the same point I started from, then the size of the circle doesn't matter, and neither does my speed. The distance between my start-point and my end-point is zero, and my average velocity is zero.
Answer:
Firstly they are, by design, easy to use in most scientific and engineering calculations; you only ever have to consider multiples of 10. If I’m given a measurement of 3.4 kilometres, I can instantly see that it’s 3′400 metres, or 0.0034 Megametres, or 3′400′000 millimetres. It’s not even necessary to use arithmetic, I just have to remember the definitions of the prefixes (“kilo” is a thousand, “megametre” is a million, “milli” is a thousandth) and shift the decimal point across to the left or the right. This is especially useful when we’re considering areas, speeds, energies, or other things that have multiple units; for instance,
1 metre^2 = (1000millimetre)^2 = 1000000 mm^2.
If we were to do an equivalent conversion in Imperial, we would have
1 mile^2 = (1760 yards)^2
and we immediately have to figure out what the square of 1760 is! However, the fact that SI is based on multiples of 10 has the downside that we can’t consider division by 3, 4, 8, or 12 very easily.
Secondly they are (mostly) defined in terms of things that are (or, that we believe to be) fundamental constants. The second is defined by a certain kind of radiation that comes from a caesium atom. The metre is defined in terms of the second and the speed of light. The kelvin is defined in terms of the triple point of water. The mole is the number of atoms in 12 grams of carbon-12. The candela is defined in terms of the light intensity you get from a very specific light source. The ampere is defined using the Lorentz force between two wires. The only exception is the kilogram, which is still defined by the mass of a very specific lump of metal in a vault in France (we’re still working on a good definition for that one).
Thirdly, most of the Imperial and US customary units are defined in terms of SI. Even if you’re not personally using SI, you are probably using equipment that was designed using SI.
Explanation:
(a) From E=
r
2
k
e
Q
Q=
k
e
Er
2
=
(8.99×10
9
N⋅m
2
/C
2
)
(8.90×10
2
N/C)(0.750m)
2
=5.57×10
−8
C
But Q is negative since
E
→
points inward, so
Q=−5.57×10
−8
C=−55.7nC
(b) The negatve charge has a spherically symmetric charge distribution, concentric with the spherical shell
