Two points A and B on the surface of the Earth are at the same longitude and 60.0° apart in latitude. Suppose that an earthquake at point A creates a P wave that reaches point B by traveling straight through the body of the Earth at a constant speed of 7.80 km/s. The earthquake also radiates a Rayleigh wave, which travels across the surface of the Earth in an analogous way to a surface wave on water, at 4.50 km/s.
(a) Which of these two seismic waves arrives at B first?
(b) What is the time difference between the arrivals of the two waves at B? Take the radius of the Earth to be 6 370 km.