Question

A swimmer swimming at 3 m/s with respect to the river wishes to cross the river flowing at speed of 2 m/s in minimum distance. If width of river is 100 m, time taken by swimmer is
$20 \sqrt{n} \: s$
Find n.​

Answer 1

Answer:

n = 5m per sec

Explanation:

if you divide 20 divide 100

0 0 cut

then your ans 5

Answer 2

Given: speed of swimmer = 3m/s

           speed of river = 2m/s

           width of river = 100m

          time taken by the swimmer = 20$\sqrt{n}$

To find: The value of n

Solution: Velocity is the vector quantity. Two or more velocity when come together will be added and subtracted according to the law of addition of vector. The resultant velocity by which the swimmer swims is according to the formula -

V resultant = $\sqrt{v1^2 - v2^2}$

If v₁ is the velocity of a swimmer, v₂ is the velocity of the river

   = $\sqrt{3^2 - 2^2}$

  = $\sqrt{9 - 4$

  = $\sqrt{5}$ m/s

Now, since the distance travelled by the swimmer to cross the river is 100m

Time taken by the swimmer to cross the river will be calculated according to the law of kinetics.

Time taken will be = distance/velocity

                              = 100/$\sqrt{5}$

                               =20 $\sqrt{5$ m/s

Therefore, the value of n is 5.