suppose you had two small boxes, each containing 1.0 g of protons. (a) If one were placed on the moon by an astronaut and the other were left on the earth, and if they were connected by a very light (and very long!) string, what would be the tension in the string?

Answer: 4.5 x 10^-36 N

Explanation: The interaction between the charges is not electrical because the distance (between the protons) is too large.

The interaction is gravitational because one is placed on earth and the other on the moon.

The force of repulsion between these two protons can be gotten using newton's law of gravitational force which is mathematically given below as

F = (G*m1*m2) / r²

F = Gravitational force

G = gravitational constant = 6.674 x 10^-11

m1 = mass of the first proton = 1g=0.001kg

m2 = mass of second proton = 1g=0.001kg

r = distance between the earth and the moon = 3.844 x 10^9m

Slotting the parameters into the formula, we have that

F = 6.674x10^-11 x 0.001 x 0.001 / (3.844 x 10^9) ²

F = 6.694 x 10^-17 / 14.77 x 10^18

Finally

F = 4.5 x 10^-36N