Answer:
To write a number in scientific notation. First write a decimal point in the numbers so that there's only one digit to the left of the decimal point.
Answer:

Explanation:
Assuming the pith balls as point charges, we can calculate the repulsive force between them, using Coulomb's law:

We observe that the magnitude of the electric force is directly proportional to the product of the magnitude of both signed charges(
) and inversely proportional to the square of the distance(d) that separates them.
Replacing the given values, where k is the Coulomb constant:

F=m*a
F=65 kg *9.8 m/s^2
F=637 N (Newtons) — this is the weight