A river is flowing from west to east with a speed of $5\, m / \min$. A man can swim in still water with a velocity $10\, m / \min$. In which direction should the man swim so, as to take the shortest possible path to go to the south ?
Let the swimmer swims at an angle $\theta$ with the vertical.
$\therefore \sin \theta =\frac{v_{r}}{v_{s}}=\frac{5}{10}=\frac{1}{2}=\sin 30^{\circ}$ $\theta =30^{\circ}$ The swimmer should swim $30^{\circ}$ east of south to take the shortest possible path to go to the south.
It is a vector quantity. A vector quantity is a quantity having both magnitude and direction. Speed is a scalar quantity and it is a quantity having a magnitude only. Motion in a plane is also known as motion in two dimensions.
Equations of Plane Motion
The equations of motion in a straight line are:
v=u+at
s=ut+½ at2
v2-u2=2as
Where,
v = final velocity of the particle
u = initial velocity of the particle
s = displacement of the particle
a = acceleration of the particle
t = the time interval in which the particle is in consideration
