Answer to the Question 02/96
The question was:Surface of a river has a slope. Can a body freely float in the water with velocity exceeding the velocity of the river.
No correct answers have been submitted. The answer is NO for the following reasons:
Body floating in the water expels amount of water equal to its weight. Thus, we can simply replace the body by water which will fill its place. This replacement water will not flow faster than the rest of the water. In slightly different terms: If the body moves downstream faster than the water, it actually moves the same amount of water upstream; therefore, there is no energetic advantage (no gain of potential energy) in moving the body downstream.
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