Question

a boat has speed 12 m per second in still water. this boat passes through a river moving at 5 m per second at right angle to the motion of the boat. what is the speed of boat in water​

Answer 1

answer

tharo bhai joginder

Answer 2

Given info : a boat has speed 12 m per second in still water. this boat passes through a river moving at 5 m per second at right angle to the motion of the boat.

To find : the speed of boat in water is ...

solution : see diagram,

speed of boat in still water, $v_b$ = 12 m/s along south

speed of stream, $v_s$ = 5 m/s along north

from Pythagorus theorem,

   $v_{b,s}^2=v_b^2+v_s^2$

= 12² + 5² = 144 + 25 = 169 = 13²

so $v_{b,s}$ = 13 m/s

therefore the speed of boat in water is 13 m/s