# Electrostatics, finding velocity

by physics604
Tags: electrostatics
 P: 85 1. An electron orbits the nucleus of an atom with velocity v. If this electron were to orbit the same nucleus with twice the previous orbital radius, its orbital velocity would now be a) $\frac{v}{2}$ b) v c) 2v d) $\frac{v}{√2}$ 2. Relevant equations $\Delta$Ek + $\Delta$Ep = 0 ? 3. The attempt at a solution I'm not really sure how I should start this question. None of the equations I have include both the v and the r variable.
 Mentor P: 38,900 What is the equation for electrostatic attraction?
 P: 85 F = kQ1Q2 / r2 But I don't see how that helps.
Mentor
P: 38,900

## Electrostatics, finding velocity

 Quote by physics604 F = kQ1Q2 / r2 But I don't see how that helps.
And the equation that we use for centripital force for uniform circular motion? There is a reason that we ask you to list the Relevant Equations...

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