Q2. Suppose instead the coin was tossed in the air with an initial velocity of 4.5 m/s (up). What is the coin's velocity right before it hits
the ground

When seismic waves hit a fault, the waves are reflected off the fault. seismograph can detect these reflected seismic waves. geologists then use these data to map the fault's length and depth

It is either a  proton or a neutron im almost positive. hope this .

Lexy is correct because angle r is between the incident wave,  n  = 0, and a diffracted wave.