Answer:
The outside of a neuron has more sodium ions while at resting state. When a electrical signal is going to pass through, the sodium channels open up first and the positive sodium ions rush inward making the inner side more positive. This is called action potential.
There is layer of fatty substances called as Myelin Sheath over the course of axons. It helps the electrical signal to be transmitted with a fast pace and efficiently over the course.
Answer:
The answer is below
Explanation:
Newton's law of gravity states that the force between two bodies is directly proportional to the product of their masses and inversely proportional to the square of the distance between them. The law is expressed by the formula:

The masses and distances for this question is in common units, Therefore the result would be in ratios
a) 4 MEarth / 2 MSolar / 3 AU
The force (F) = (4 * 3) / 3² = 4/3
b) 1 MEarth / 1 MSolar / 1 AU
The force (F) = (1 * 1) / 1² = 1
c) 1 MEarth / 2 MSolar / 2 AU
The force (F) = (1 * 2) / 2² = 1/2
Circular Motion does occur on earth, so yes, true