Question

The earth revolves around the sun with an angular velocity of 2×10^-7rad/s in a circular orbit of radius 1.5×10^8km. The force exerted by the sun on the earth in newton is?

(a) 30×10^21

(b) 27×10^39

(c) Zero

(d) 18×10^25

This question was addressed to me in an international level competition.

The question is from Gravitational Potential Field in portion Mechanical Properties of Solids of Engineering Physics I

Answer 1

The correct answer is (a) 30×10^21

To elaborate: Force exerted by the sun = Centripetal force

F = Mrω^2

F = 6×10^24×1.5×10^11×(2×10^-7)^2 = 36×10^21 N