A motorboat can maintain a constant speed of 13 miles per hour relative to the water. The boat makes a trip upstream to a certain point in 63 minutes; the return trip takes 15 minutes. What is the speed of the current?

  8 mph

Step-by-step explanation:

The speed in each direction is the speed of the boat with the speed of the current appropriately added. If x is the speed of the current, the upstream speed is 13-x; the downstream speed is 13+x.

The ratio of times is inversely proportional to the ratio of speeds, so we ahve ...

  15/63 = 5/21 = (13-x)/(13+x)

  5(13 +x) = 21(13 -x) . . . . . . . cross multiply

  26x = 13(21 -5) = 13·16

  x = 13·16/26 = 16/2 = 8

The speed of the current is 8 miles per hour.

step-by-step explanation:

we can use this expression to calculate the energy gain as a particle moves with a field or the energy loss as it moves against it. (note that it is also used to define the electron-volt, a unit of energy equal to that gained by an electron as it falls through a pd of 1 v, i.e. w = 1 ev = 1.6 10-19 c 1 v = 1.6 10-19j).in fact this expression is really nothing more than the statement that potential is the potential energy per unit charge. in this case, v= w/qis simply stating that the change in potential energy(or work done) per unit charge is equal to the change in potential (or potential difference), v.student questions: uniform electric fields2electron beamcathode+5 kvanode0 v

step-by-step explanation: