1. Tardigrade
  2. Question
  3. Physics
  4. The speed of boat is 5 km/hr in still water. It crosses a river of width of 1 km along a shortest possible path in 15 minutes. Then velocity of the river is:

Question Error Report

Thank you for reporting, we will resolve it shortly

Back to Question

Q. The speed of boat is 5 km/hr in still water. It crosses a river of width of 1 km along a shortest possible path in 15 minutes. Then velocity of the river is:

JIPMERJIPMER 1998

Solution:

Here: speed of boat in still water $ {{\upsilon }_{b}}\,=5\,\,km/hr $ width of river = 1 km Time taken to cross the river along shortest possible path = 15 min = $ \frac{1}{4} $ hour Hence resultant velocity of the boat $ =4\,km\text{/}hr $ Then the velocity of river $ =\sqrt{{{(5)}^{2}}-{{(4)}^{2}}}=3\,km\text{/}hr $