A swimmer, capable of swimming at a speed of 1.60 m/s in still water (i. e., the swimmer can swim with a speed of 1.60 m/s relative to the water), starts to swim directly across a 1.25-km-wide river. However, the current is 0.549 m/s, and it carries the swimmer downstream. (a) How long does it take the swimmer to cross the river

  t = 781.25 s

Explanation:

This is an exercise in velocity composition, if we set a reference system where the x-axis is perpendicular to the river and the y-axis is parallel to the river.

The swimmer has a velocity on the x axis

           vx = 1.60 m / s

a velocity on the y axis, created by the current of the river

           vy = 0.549 m / s

time is a scalar, therefore the time it takes to cross the river is the same time it creates the displacement in e; Axis y

X axis

            vₓ = x / t

            t = x / vₓ

            t = 1250 / 1.6

            t = 781.25 s

in this time a distance has descended

            y = v_y t

            y = 0.549 781.25

            y = 428.9 m

answer: option c. i.e. electric current flowing “downhill” from the negative electrode to the positive electrode in a battery

explanation:

the water analogy to the circuits define the pipes (water flows) to the electric current. now, we know that the electric current flows from the positive terminal to the circuit (as shown in the diagram attached).

hence, option c is the correct answer.

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