Kinematics Question 317
Question: A river it’s flowing from W to E 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. [BHU 2005]
Options:
A) 30° with downstream
B) 60° with downstream
C) 120° with downstream
D) South
Show Answer
Answer:
Correct Answer: C
Solution:
For shortest possible path man should swim with an angle (90+q) with downstream. From the fig, $ \sin \theta =\frac{v _{r}}{v _{m}}=\frac{5}{10}=\frac{1}{2} $
therefore
$ \therefore $ q = 30° So angle with downstream = $ 90{}^\circ +30{}^\circ =120{}^\circ $
