I'm in the middle of a final, and I need the answer to this problem, please help!

An atom that has gained or lost electrons is called an _

Intro: a solid ball of radius rb has a uniform charge density ρ. part a: what is the magnitude of the electric field e(r) at a distance r> rb from the center of the ball? express your answer in terms of ρ, rb, r, and ϵ0. part b: what is the magnitude of the electric field e(r) at a distance r express your answer in terms of ρ, rb, r, and ϵ0. part c: let e(r) represent the electric field due to the charged ball throughout all of space. which of the following statements about the electric field are true? check all that apply. e(0) = 0 e(rb)=0 limr→∞e(r)=0 the maximum electric field occurs when r=0 the maximum electric field occurs when r=rb the maximum electric field occurs as r→∞.

If a car has a speed of 20 m/s, how long will it take to go 155 m? a. 3100 s b. 135 s c. 2.1 s d. 7.8 s