<span>So we want to know which answer best describes the flow of electric charge. So the flow of electric charge is when the charge is moving from a higher potential energy to a lower potential energy which would be analogous to the rock rolling down hill. So first answer is correct. </span>
Constructive interference means that the waves combine instead of negate. if they are both amplitude x, adding them together would result in 2x, or doubling the amplitude of one of the waves
The van's AVERAGE speed on the way up the hill is
(1/2) (20 + 12) = (1/2) (32) = 16 m/s .
At an average speed of 16 m/s, it travels
(16 m/s) x (8 s) = 128 meters in 8 seconds.