In the analogy for how a wave travels along a line of dominoes standing on end, the way the dominoes fall over one after another in place represents .
A. a wave
B. the initial disturbance
C. the energy of the wave
D. particles in the substance
In the analogy for how a wave travels along a line of dominoes standing on end, knocking over the first domino represents .
A. a wave
B. the initial disturbance
C. the energy of the wave
D. a particle in the substance
*the initial disturbance is incorrect for both of them*

The answer which is not a detail carson used to describe the pool in the cave at low tide is b.  hundreds of periwinkles browse the branches and roots of the trees. 

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.