How much work is required to bring three protons, initially infinitely far apart, to a configuration where each proton is 1.5×10−15m from the other two? (this is a typical separation for protons in a nucleus.) express your answer using two significant figures.

Explanation:

The work done(W) in bringing 2 protons to a separation 'r' is given as:

where,

k= coulomb's constant = 9 × 10⁹ N

q = charge of protons = 1.6 × 10⁻¹⁹ C

Now, the third charge (or proton) is brought near the other two  protons

Thus, work done against both these is

Now,

The total work done (W) =

or

or

conservation of mass

mass before something happens = mass afterwards