a. A moon is in the new phase between its planet and the star around which they orbit. The moon orbits its planet at an average distance of 1.9110⁸ m and has a 1.2510²¹ kg. The planet orbits its star at an average distance of 3.0110¹² m and has a 8.6810²⁵ kg. The star has a mass of 1.9910³⁰ kg. What is the ratio of the planet's force of gravity on the moon to the star's force of gravity on the moon when the moon is in new phase to two significant digits?

[hint: the planet should pull with a larger force than the star]

b. A neodymium magnet creates a force of 39.2 N on a piece of steel at a separation of 5.50 mm between the center of tthe magnet and the piece of steel. With what force in newtons would the magnet pull on the steel at a separation 14.2 mm to two significant digits?

c. A charged plastic hair comb is shown to have a charge of 108 nC. If it polarizes a piece of paper to an equal charge and is separated from it by 15 mm, what electrical force in newtons does the comb exert on the piece of paper to two significant digits?