A river has a width of 23m. A row boat has a velocity of 4m/s on still water. The river flows with a velocity of 6m/s.
Calculate the time taken for the boat to cross the river.

t = 5.75 sec.

Explanation:

A river has a width of 23m. A row boat has a velocity of  4m/s on still water.

The river flows with a velocity of 6m/s.

find:

Calculate the time taken for the boat to cross the river.

                        a             b

                        |            /              

                        |         /               Vr = 6m/s

                        |      /                       23m

                        |   /

                     boat    v = 4m/s

vertical motion:

X = V.t

where X is the width of the river = 23m

V is the speed of the boat with respect to river = 4m/s

t is the time trip it takes.

plug in values into the formula:

23m = 4 m/s * t

t = 5.75 sec.

therefore, the time it takes for the boat to cross the river is 5.75 seconds