Solution to problems – class 9 – Set 1 Q35

Last updated on June 18th, 2019 at 06:15 am

Problem Statement

What is the force of gravity on a body of mass 150 kg lying on the surface of the earth ?
(Mass of earth = 6 × 10^24 kg; Radius of earth = 6.4 × 10^6 m; G = 6.7 × 10–11 Nm2/kg^2)

Solution

M1 = mass of the body = 150 kg
M2 = mass of the earth = 6 x 10²⁴ kg

Distance between the body and the center of the earth = radius of the earth = r = 6.4 × 10⁶ m

Force of gravity on the body = gravitational force between the body and the earth = F

F = (G M1 M2) / r² = (6.7 x 10 ^-11) (150 x 6 x 10²⁴) / (6.4 × 10⁶) ² = 1472 N

Question Set – Physics Problems for grade 9