physics
posted by maria on .
An earthquake generates three kinds of waves: surface waves (L waves), which are the slowest and weakest; shear (S) waves, which are transverse waves and carry most of the energy; and pressure (P) waves, which are longitudinal waves and travel the fastest. The speed of P waves is approximately 7.0 km/s, and that of S waves is about 4.0 km/s. Animals seem to feel the P waves. If a dog senses the arrival of P waves and starts barking 23.3 s before an earthquake is felt by humans, approximately how far is the dog from the earthquake’s epicenter?

217.7 km i found it. thankss

A sinusoidal wave on a string is described by the equation y = (0.169 m) sin (0.713 x  41.9 t), where x and y are in meters and t is in seconds. If the linear mass density of the string is 10.1 g/m ...
a) ... the phase of the wave at x = 2.27 cm and t = 0.175 s. ?
b)... the speed of the wave ?
c)... the wavelength.
d) ... the power transmitted by the wave. ? 
How did you done?