C) alternating current .
<span>
B)direct current </span>
Answer:
613373.65233 m/s
Explanation:
M = Mass of Sun = 
m = Mass of Earth
v = Velocity of Earth
r = Distance between Earth and Sun = 
= Radius of Earth = 
= Radius of Sun = 
In this system it is assumed that the potential and kinetic energies are conserved
The velocity of Earth would be 613373.65233 m/s
Answer:
Because of the presence of air resistance
Explanation:
When an object is in free fall, ideally there is only one force acting on it:
- The force of gravity, W = mg, that pushes the object downward (m= mass of the object, g = acceleration of gravity)
However, this is true only in absence of air (so, in a vacuum). When air is present, it exerts a frictional force on the object (called air resistance) with upward direction (opposite to the motion of free fall) and whose magnitude is proportional to the speed of the object.
Therefore, it turns out that as the object falls, its speed increases, and therefore the air resistance acting against it increases too; as a result, the at some point the air resistance becomes equal (in magnitude) to the force of gravity: when this happens, the net acceleration of the object becomes zero, and so the speed of the object does not increase anymore. This speed reached by the object is called terminal velocity.
