Two point charges are 3.00 cm apart. They are moved to a new separation of 2.00 cm. By what factor does the resulting mutual force between them change?

By a factor of 9/4

Explanation:

Applying Coulomb's law,

F = kqq'/r² Equation 1

Assuming q and q' are the two point charges respectively.

Where k = coulomb's constant, r = distance between the charges.

When the point charges are 3.0 m apart,

F = kqq'/3²

F = kqq'/9 Equation 1

When they are moved to a new distance, 2.00 m

F' = kqq'/2²

F' = kqq'/4 Equation 2.

Comparing equation 1 and equation 2.

F' = 9F/4

Hence the resulting mutual force change by a factor of 9/4

the right answer is 0.3 meters per second