Consider two people, each of mass 60 Kg, a distance of 10 m apart.?

Question

Consider two people, each of mass 60 Kg, a distance of 10 m apart.

(a). Assuming that all the mass in each person is made out of water, estimate how many electrons there are in each person.

(b). Hence, estimate the electrostatic force of repulsion between the two people due to the electrons.

(c). What other simplifying assumptions have you made to make your estimate possible?

(d). No such force is observed in practice. Give one reason why this is so.

I need this urgently, who ever answers all of them first gets chosen as best answer!

Thanks for all help in advanced.

Answer 1

Hello Moto-

As requested...first and correct.

a) 60 kg of H2O is 3333.33 moles or 2.01 E27 molecules (18g/mole and then use Avogadro's number...OK?)

Each molecule has 8 electrons...so there are about 1.61 E28 electrons in each "person"

b) F(repulsion) = kQ1Q2/d^2 where Q1=Q2=2.57 E9 Coulombs (each elec. has a charge of 1.60E-19 C), k=9.0 E9 (about) and d=10m

F= 5.94 E26 Newtons (more than enough to send each "person into orbit!)

c) We assumed that a person is solid water.  We assumed that all the electrons of each person act at a point and repell the electrons only of the other person.  (We simplified the geometry).

d) We assumed that there are no protons...which there are...and that balances the electrons so that there is no net charge on either "person" except for static electricity.

-Fred