The epicentre of an earthquake is the point on the Earth's s

The epicentre of an earthquake is the point on the Earth's surface nearest to the site of the earthquake.An earthquake produces waves.These waves spread out from the epicentre of the earthquake and travel along the Earth's surface.
(a) One wave is emitted very second.What is the frequency of thes waves?
(b) These surface-waves travel at a constant speed of 6000m/s through materials commonly found on land.Calculate the wavelength of these waves.
(c) The diagram below shows the surface-waves from the epicentre A travelling along the Earth to a point B exactly opposite the epicentre.The radius of the Earth,r,is 6400km.Calculate the distance travelled by the waves from A to B and the time taken.(Circumference of a circle=2∏r,take ∏=3.14)
(d) Give one reason why these waves might not reach B.