The bar magnet and the electromagnet act identical. The difference being a electromagnet is a coil of wire that has a power source connect to both ends, this energizes the coil with an electromagnetic field.
Answer:

Explanation:
In this case, since the charged particle moves in circular motion, the centripetal force is equivalent to the magnetic force.

Answer:
A. 1.6 N/cm
Explanation:
spring constant = 21/13 = 1.6 N/cm
Answer:
505929 AU
Explanation:
As you may know, one light-year is equivalent to approximately 63241.1 Astronomical Units. To get your answer, simply multiply 63241.1 * 8 to get ≈505929 AU