Question

A motorboat going downstream overcame a raft at a point A: T= 60 mins later it turned back and after some time passed the raft at a distance l= 6 km for point A. Find The Velocity assuming the duty of the engine to be constant.???

Answer 1

from the given data, velocity of raft can be calculated as:
v=6km/hour

Answer 2

sorry dude but the answer is wrong........ the velocity of the flow or raft is 3 km/hr

Answer 3

pls explain how.

Answer 4

am sorry, but the ques is not correctly asked . the language and the data is improper.......

Answer 5

U cant say dat....becaz dis is a question from the buk " General Problems In Physics By I.E.Irodov".... which is one of The Best Physics Buks in The World....and According to my question u hv to find the velocity of the flow of the river...

Answer 6

then u haven't typed it correctly. because nowhere in the ques you have asked velocity of the flow or raft.............

Answer 7

sry sir ......

Answer 8

it is using speed=distance/time
for going and coming back,time=120minutes=2hrs(constant speed of motor)
in that time raft moves 6km
so speed=?

Answer 9

the question only specifies the going time for the motorboat, not the coming back time. it's a little bit more complicated.

Answer 10

same speed same distance same time......wat is the missing one here?
everything given

Answer 11

@salini : then pls solve it.....

Answer 12

speed=distance/time

velocity/speed=6km/2hrs=3km/hr

Answer 13

velocity or speed it doesnt matter here

Answer 14

but he forgot to mention in the ques : whose velocity is he asking............ the motorboat or the raft..............

it should be the raft's speed......

then its ok...........

Answer 15

i am asking the speed of the raft/flow of river

Answer 16

if the river is flowing, then the raft wouldn't be stationary. it's velocity=velocity of river. Hence the distance travelled by motorboat downstream will not be equal to the distance travelled upstream to the raft as the raft has moved downstream itself. It clearly says in the question that motorboat crosses the raft at point A and when coming back they meet at a distance of 6km from point A. Plus since the river has a velocity, the velocity of the motorboat downstream will not be equal to the velocity of the motorboat upstream.

Hence it's not the same speed or same distance. In my opinion, the question specifies that the velocity of motorboat in STILL water would be constant, which is meant by the duty of the engine.

Answer 17

yes the motorboat also gets displaced if it were moving along with water speed,but here we know that the motor bota comes back to the same point from where it started(i am not considered about the work the motorboat has to do against the flowing current in order to stay in a straight line)
it caomes back to the same position when after how much time?
in that time our raft wud have drifted away from A