Question

The mean orbital radius of the earth around the sun 1.5 × 108 km. Calculate the

mass of the sun if G = 6.67 × 10-11 Nm2/kg -2?​

Answer 1

M = 1.994 × 10^(30) kg

Step-by-step explanation:

We are given;

Orbital radius; r = 1.5 × 10^(8) km = 1.5 × 10^(11) m

Gravitational constant; G = 6.67 × 10^(-11) N.m²/kg²

If the orbit is circular, the it means the gravitational force is equal to the centripetal force.

Thus; F_g = F_c

GMm/r² = mv²/r

Simplifying gives;

GM/r = v²

M = v²r/G

Now, v is the speed of the earth around the sun and from online sources it has a value of around 29.78 km/s = 29780 m/s

Thus;

M = (29780^(2) × 1.5 × 10^(11))/6.67 × 10^(-11)

M = 1.994 × 10^(30) kg