The longitudinal vibrations of a semi-infinite flexible rod satisfy the wave equation utt = c2uxx for x > 0. Assume that the end x = 0 is free (ux = 0); it is initially at rest but has a constant initial velocity V for a < x < 2a and has zero initial velocity elsewhere. Plot u versus x at the times t = 0, a/c, 3a/2c, 2a/c, and 3a/c

Which principle states: "geologic processes taking place on earth today operated similarly in the past and can be used to explain past geologic events"? a. lateral continuity

Answer(a)   the matererials that are in contact, the two materials and the nature of their surfaces/// (b)/// the force pushing the two surfaces together, pushing the surfaces together causes the more of the asperities to come together and increases the surface area in contact with each other

Distance covered = speed x timethe distance traveled going against the stream = distance traveled with the stream.therefore it is the speed and the time that are the variables.as he travels the same distance both ways, speed x time is the same for each way.going upstream his speed is 4 kph; going downstream his speed is 6 kph.therefore we have two simultaneous equations: time upstream x 4 = time downstream x 6time upstream + time downstream = 60 minutestherefore we have the equation: time upstream = 6/10 hour, time downstream therefore = 4/10 hour.distance traveled at 4km/hr in 6/10 hour = 24/10 = 2.4km.check: distance traveled at 6km/hr in 4/10 hour = 24/10 = 2.4km.