Modern Physics> kinematics...

A boat which has a speed of 5km/hr in still water crosses a river of width 1km along the shortest possible path in 15 minutes. The velocity of the river water in km/hr is ?

aditya bhardwaj , 15 Years ago

Grade 11

9 Answers

mohit sengar

the velocity of the river is 3 km /h

Last Activity: 15 Years ago

aditya bhardwaj

please explain how idont want the answer but how the answer comes?

Last Activity: 15 Years ago

Fawz Naim

let the velocity of the river be x. the velocity of the river will be in the horizontal direction

velocity of boat in still water is 5km/hr. As the width of the river is 1 km and time taken by the boat to cross the river along the shortest path is 15 min therefore the velocity of the boat is= 1*60/15= 4km/hr

according to the figure the velocity of the river is along AB . By applying triangle law of vector addition the value of AB comes to be 3km/hr

Approved

Last Activity: 15 Years ago

karthik s

how the boat go in the direction CA and river in AB pls explain the direction of river and moving boat

Last Activity: 9 Years ago

Himanshu Kumar

As the boat crosses the river it experiences two forces one horizontal direction (by the river along AX) and another by the one who rows the boat (in the vertical ditection along AB) X A ------ v=3m/s

Last Activity: 8 Years ago

Preethi P Gowda

The width of the river=1.0kmThe boat crosses the river in 15 minutes The resultant velocity of boat =1.0km/0.25h=4km/hVelocity of river=(5²-4²)½ =3km/h

Last Activity: 8 Years ago

Kanishka agrawal

Given - v=5km/hr S=1km t=15/60 hr. From second eq . Of motion 1=1/2×a×(15/60)^2a=8m/s^2From first eq . Of motion5= u+8×15/60 Hence u=3km/hr

Last Activity: 8 Years ago

Rohan takmoge

Velocity= distance /time

= 1km /0.25 hr. ......(15 min=0.25hrs)

= 4 km/hr

The velocity of the river water is 4 km/hr

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Last Activity: 7 Years ago

yash singh

Let V be the speed of boat and V’ be the speed of river. Let d be the width of river. Let T be the time taken. According to question V=5km/hr , d=1 km and T= ¼ hr. Now simply put these values in the formula T= d/√V^2 + V’^2 . From here, V’ = 3km/hr.

Last Activity: 6 Years ago