Chapter 16, Problem 11Q

To determine

To compare Coulomb’s law and Newton’s law of gravitation

Answer to Problem 11Q

Solution:

Coulomb force can be attractive, or repulsive but gravitational force is attractive only.

Explanation of Solution

Coulomb’s law: The electrical force between two charges is directly proportional to the product of charges and inversely proportional to the square of the distance between them.

That is, $F=\frac{K{q}_1{q}_2}{r^2}$

Newton’s law of gravitation: The gravitational force between two masses is directly proportional to the product of masses and inversely proportional to the square of the distance between them.

That is, $F=\frac{G{m}_1{m}_2}{r^2}$

Where K and G are constants.

So, both Coulomb’s law and gravitational law are conservative and obey inverse square law. The main difference between them is that Coulomb force can be attractive or repulsive because there are positive and negative charges. But gravitational force is attractive only since there is only one kind of mass.

The value of gravitational constant is very small as compared to the electrical constant.

The charge plays the same role in the Coulomb’s law that the mass plays in the Newton’s law of gravitation.