The question is Multiple-Concept Example 3 illustrates several of the concepts u

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Multiple-Concept Example 3 illustrates several of the concepts usedin this problem. A single electron orbits a lithium nucleus thatcontains three protons (+3e). The radius of the orbit is1.89 x 10-11 m. Determine the kinetic energy of theelectron.

I was given the hint to use three equations. Kinetic entergy,Force (mass X accel) and Accel = V2 / r. Irearranged the equations to solve for velocity squared since itseemed as if that was the only thing missing. I looked up theelectron's mass as 9.11 x 1031 kg.   I triedsolving this and was not able to come up with the correct answer onseveral tries.   Please help. Thanks!

Explanation / Answer

given radius of orbit = r = 1.89*10-11m charge of electron = q1 =1.6*10-19 c charge of proton = q2 =3*1.6*10-19 c = 4.80*10-19 c mass of electron = m = 9.11*10-31 kg k = 9*109 N.M2/c2 an electron of mass m that moves with a constant speed von a circular path of radius r expereiences a net centripetalforce    Fc = mv2/r----(1) and Fc =kq1q2/r2----(2) then speed of the orbiting electron v = Fc*r/m from 1 from2 v= Kq1q2/mr plug values we get v = 6.33*106m/s K.E = 1/2 mv2 = 1/2*9.11*10-31(6.33*106)2                            = 182.58*10-19 J                            = 1.82*10-21J                            = 182.58*10-19 J                            = 1.82*10-21J   

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