Newton's Law of Gravitation states: F=GMm/r^2, where G is the gravitational constant (6.67×10−11m^3kg^−1s^−2). Kepler's Third Law, states t^2=kR^3. The mass of the sun is 1.99x10^30kg. Find the value of k and its units

F=GMm/r2=mv2/r, v=2pir/t

equating the two values for F and remembering to include the equation for v, GMm/r^2 = m(2pir/t^2)^2/r. Rearranging to find t^2, t^2 = 4pi^2r^3/GM where 4pi^2/GM equals the constant k. Therefore for the purpose of the question, k = 2.97x10^-19s^-2m^-3.

SB

Related Physics A Level answers

All answers ▸

A child is standing on a walkway that is moving at 2 metres per second and decides to turn around and walk back to the start at 2 metres per second. Explain why the child cannot reach the start of the walkway at this speed.


Outline the principal features of a geostationary orbit and use them to explain one use of satellites in this type of orbit.


A rocket travels with constant velocity in a straight line in deep space. A ball is thrown from the back to the front (ie from the thrusters to the nose). Describe the path of the ball. Describe the path if the rocket were accelerating along this line.


Given a graph of the displacement of a particle, how can you tell if it is in Simple Harmonic Motion?