Practice!

Sample Problem

What is the gravitational attraction between the Earth and the Moon? The Earth has a mass of 5.97 × 1024 kg, while the moon has a mass of 7.36 × 1022kg. The average distance between them is 384,400km. Estimate G as 6.67 × 10-11 N (m/kg) ²

Solution

To solve this problem, we use the equation F = G (m1 m2) /r2 .

We are given that m1 = 5.97 × 1024, m2 = 7.36 × 1022, and that r = 384400000.

We plug these values into the equation and we get that

F = ((6.67 × 10-11) (5.97 × 1024,) (7.36 × 1022)) / (384400000) 2 = 1.98 × 1020 N