Solve the problem.Show that a planet in a circular orbit moves with constant speed.

Question

What will be an ideal response?

Answer 1

Kepler's first law says that the eccentricity of a planet's elliptical orbit e =  -1. The eccentricity of a circle is 0, and solving for the speed v₀ with e = 0 gives v₀ = . Since r₀ is a fixed radius for a circular orbit, all three terms for computing v₀ are constant, so v₀ is also constant.