Water is flowing in a stream
with velocity 5 km/hr in an easterly direction
relative to the shore. Speed of a boat is relative
to still water is 20 km/hr. If the boat enters the
stream heading North, with what velocity will
the boat actually travel?
Answers
Answer:
15 km/hr
Explanation:
LET VELOCITY OF STREAM THAT IS
5 km/hr =u
LET VELOCITY OF BOAT IN STILL WATER THAT IS 20 km/hr =v
AS STREAM IS MOVING EASTERLY AND BOAT IS MOVING IN NORTH DIRECTION
THAT'S WHY IT IS DOWNSTREAM VELOCITY.
DOWNSTREAM VELOCITY = ( v - u )
= 20 - 5
= 15 Km /hr
I hope this will help you out
Final Answer : n= 3
Solution:
Steps:
1) Let the relative velocity of boat be 'v' m/s making an angle with vertical .Then,the velocity of river is '2v' in horizontal direction .
Then,we will try to break velocity of boat in two components .
2) We observe that resultant velocity of boat :
3) Let the width of river be 'd' .
Time required to cross the river,t :
Since, we observed that ,so drift can't be 0.
4) That is,
Drift ,x =
=
For Drift to be minimum,
5) Hence, angle made with the vertical is 30 degree.
Therefore,angle made with the direction of river flow is 90+30=120 degree.
Hence , value of n is 3.