Answer:
1. A <em>series circuit </em>is a closed circuit which has all loads connected in a row and there is only one path for the current to flow.
2. The <em>Ohm's Law </em>state that a current flow through a resistor is directly proportional to the voltage across it 
3. A <em>parallel circuit </em>is a closed circuit divided into branches that it has two o more paths for the current to flow and the loads are parallel to each other which mean the voltage across them is the same for all loads.
Acceleration = force / mass = 20 / 2 = 10 m/s^2
Protons are positive, and neutrons are negative, electrons are neutral. I’m not sure about the rest but I hope that helps for now
Correct order, from lowest potential energy to highest potential energy:
E - C - D - B - A
Explanation:
The gravitational potential energy of the car is given by:

where
m is the car's mass
g is the gravitational acceleration
h is the height of the car relative to the ground
In the formula, we see that m and g are constant, so the potential energy of the car depends only on its height above the ground, h. The higher the car from the ground, the larger its potential energy. Therefore, the position with least potential energy will be E, since the height is the minimum. Then, C will have more potential energy, because the car is at higher position, and so on: the position with greatest potential energy is A, because the height of the car is maximum.