The distance between earth and the moon is about 384,400 kilometers. the distance can be written in scientific notation as a × 10b kilometers, where a = and b = .

, where a = 3.844 and b=5.

Explanation:

A number can be written in scientific notation as follows:

where it means that the number 'a' is multiplied by 10 to the power b.

Practically speaking, it means that in order to write a number in scientific notation, we must move the dot to the left by 'b' positions. In this problem, we have the following number:

384400 km

Therefore, we have to move the dot to the left by 5 position, so we get:

and we can get rid of the '00' since they are meaningless:

there are no contact forces mentioned on the list of choices that you've provided.