Question

Learning Objectives As part of this activity, you want to be able to: Experimentally verify that the strength of the Coulomb force between two charged bodies varies inversely with the square of the separation distance between them. Experimentally verify that the strength of the Coulomb force between two charged bodies varies with the product of the charges. 1.1 Pre-lab Gravitational force Last semester you may have encountered Newton's universal law of gravitation. This law, which describes the force between two point like masses, is mi m2 R2 where, G is Newton's gravitational constant and has an approximate value of 6.674x 10-11 m3/kg s2. mi, m2 are the masses of particles 1 and 2 respectively, R is the distance between the two particles. Although this equation is valid for point-like particles, for R r (r is the radius of the larger of the two objects) this equation gives a good approximation. For the Earth-moon system R is about 60 times the radius of the Earth, so we can expect a reasonable result

Answer 1

[1.1]

1. Mass of Earth (m₁)=5.972 × 10²⁴ kg

Mass of Moon(m₂)=7.35 x 10²²kg

Distance between Earth and Moon(R)= 382,500,000 mts=3.82 × 10⁸ m

G = 6.67 × 10^-11 m³/kg.s²

F_g = G m₁m₂/R^{2 =} 6.67 × 10^-11 m³/kg.s²  x 5.972 × 10²⁴ kg x 7.35 x 10²²kg / (3.82 × 10⁸ m)²

=2× 10²⁰ N (approx.)

2. The electric force between Earth and moon will be smaller, as electric force takes place between charged body only. As we know that both earth and moon have negligibe charge, so the electric force between them will also be negligible.

3. The fundamental difference between mass and charge of an object is that mass is the measure of inertia of a body where as charge is the measure of electrical property of the body. Also, mass of a body can never be zero, where as the charge can be zero, which can result in such big difference in gravitaional and electric force between two body.