E) Protons, neutrons, and electrons
True ..............................
Answer: rp/re= me/mp= 544 * 10^-6.
Explanation: To calculate this problem we have to consider the circular movement by the electron and proton inside a magnetic field.
Then the dynamic equation for the circular movement is given by:
Fcentripetal= m*ω^2.r
q*v*B=m*ω^2.r
we write this for each particle then we have the following:
q*v*B=me* ω^2*re
q*v*B=mp* ω^2*rp
rp/re=me/mp=9.1*10^-31/1.67*10^-27=544*10^-6
Technically you can go forever on and on, but maybe your question was like how many rotations in a certain distance?
D is the answer
To get the density you divide mass by volume
So the equation is 400/60=d