Imagine for a minute that the Moon is held in its orbit about the ...

[waynest]

Imagine for a minute that the Moon is held in its orbit about the Earth by electrical forces rather than by gravitation. What electrical charges -Q on the Earth and +Q on the Moon are necessary to hold the Moon in a circular orbit with a period of 27.3 days? The Earth-Moon distance is 384 000 km and the mass of the Moon is 7.35  1022 kg.

Question 2

An alpha particle (charge = +2e) is sent at high speed toward a gold nucleus (charge +79e). What is the electrical force acting on the alpha particle when it is at a distance of 2  10-14 m away from the gold nucleus? (e = 1.6  10-19 C)

[joanwhite]

Answer to Question 1

Q = 5.73  1013 C

Answer to Question 2

91 N