The given velocity is 465 m/s.
Part a.

Answer: 1674 km/h
Part b.

Answer: 40,176 km/day.
Thank you for your question, what you say is true, the gravitational force exerted by the Earth on the Moon has to be equal to the centripetal force.
An interesting application of this principle is that it allows you to determine a relation between the period of an orbit and its size. Let us assume for simplicity the Moon's orbit as circular (it is not, but this is a good approximation for our purposes).
The gravitational acceleration that the Moon experience due to the gravitational attraction from the Earth is given by:
ag=G(MEarth+MMoon)/r2
Where G is the gravitational constant, M stands for mass, and r is the radius of the orbit. The centripetal acceleration is given by:
acentr=(4 pi2 r)/T2
Where T is the period. Since the two accelerations have to be equal, we obtain:
(4 pi2 r) /T2=G(MEarth+MMoon)/r2
Which implies:
r3/T2=G(MEarth+MMoon)/4 pi2=const.
This is the so-called third Kepler law, that states that the cube of the radius of the orbit is proportional to the square of the period.
This has interesting applications. In the Solar System, for example, if you know the period and the radius of one planet orbit, by knowing another planet's period you can determine its orbit radius. I hope that this answers your question.
Answer:
The voltage will quadruple
Explanation:
The power dissipated in a circuit is given by

where
V is the voltage
R is the resistance
In this problem, the voltage across the circuit is doubled:
V' = 2V
So the new power dissipated is

so, the power dissipated will quadruple.
C. Newtons third law of motion
Because eventually, the frictional forces will slow you to a halt. Newton's Third Law of Motion For every action there is an equal and opposite reaction. When they push off against the ice, or "stroke" with their skates, they are applying a force down and back against the ground.
Hope this helps!