the magnitude of its centripetal acceleration in mm/s^2

Question

The Earth is 149 million km from the sun. Assume its orbit is a circle. Find:

  (a) the speed of Earth in its orbit;

  (b) the magnitude of its centripetal acceleration.

Answer 1

HINT: If the orbit is circular, the magnitude of the force on the earth is constant throughout the orbit, since it is always at the same distance from the sun.

Use Newton's Second Law F = m x a and the equation for the gravitational force on the earth, and solve for a, the magnitude of the acceleration.

Make sure that you have used MKS units throughout. (Note that the radius of the orbit is given in km.)