12) The amount of electrical energy stored in a system of twocharged particles a distance dd apart is
UE(d)=kq1q2/d
where particle 1 has charge q1, particle 2 has charge q2, andCoulomb's constant has the value k=k= 8.99×109 Nm22/C22.
Suppose that you have two particles of charge q1=7q1=7 nC andq2=−7q2=−7 nC. Let's say that you hold the positively chargedparticle in a fixed position while you steadily move the negativelycharged particle farther and farther away at a constant speed of 3m/s. The distance between the particles therefore changes accordingto the usual distance formula
d(t)=di+vt,
where v is the given speed and di=3 mm is their initialseparation distance.
How much power do you deliver to the system at the time t=1s as yousteadily separate the particles?
