Question

4. A person can swim 0.65 m/s in still water. She heads directly south across a river 130 m wide and lands at a point 88 m [W] downstream. K/U T/I A (a) Determine the velocity of the water relative to the ground. (b) Determine the swimmer’s velocity relative to Earth. (c) Determine the direction she should swim to land at a point directly south of the starting point.

Answer 1

velocity 0.65m/s in still water, directly south

time to cross the river = 130/0.65 = 200s = t
during that time, there is a current (c) ,directly west

c*t = 88
c = 88/200
c = 0.44 m/s .........ans
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Answer 2

speed of the person in still water = 0.65 m/s

width of the river = 130 m

distance covered downstream = 88 m

a) let the speed of the water be = s

The time to cover two displacements would be equal.

`(130m)/(0.65m/s)=(88m)/(s)\\ \Rightarrow s = 0.44 m/s`

b) Swimmer's velocity relative to earth would be:

`v = √(0.65^2+0.44^2) = 0.78 m/s`

c) The swimmer should swim south of East to land at a point directly south of the starting point.