Washington D.C is roughly 3000 miles from San Francisco. When it is 8:00 a.m. in San Francisco, it is 11:00 a.m. in Washington D.C. Using this information, estimate the following.
(a) the rotational speed of the surface of Earth (mi/h)
(b) the circumference of Earth (mi/h)
(c) the radius of Earth (mi/h)