Question

HELP MEDALS TO WHOEVER HELPS!!!

Answer 1

On July 10, 1996, a granite block broke away from a wall in Yosemite Valley and, as it began to slide down the wall, was launched into projectile motion. Seismic waves produced by its impact with the ground triggered seismographs as far away as 200 km. Later measurements indicated that the block had a mass between 73000000 kg and 170000000 kg and that it landed 500m vertically below the launch point and 30m horizontally from it. What is the block's kinetic energy just before it landed?

Consider two types of seismic waves that spread from the impact point - a hemispherical body wave traveled through the ground in an expanding hemisphere and a cylindrical surface wave traveled along the ground in an expanding shallow vertical cylinder. Assume that the impact lasted 0.50 s, the vertical cylinder had a depth D of 5.0 m and each wave type received 20% of the mechanical energy the block had just before impact. Neglecting any mechanical energy loss the waves experienced as they traveled, determine the intensities of the body wave and the surface wave when they reached a seismograph 200 km away. On the basis of these results, which wave is more easily detected on a distant seismograph?