A man rows a boat across a river in time t1 and rows an equal distance down the stream in time t2. If Vm is the speed of the man in still water and Vw is the speed of the water, what is the ratio of t1 : t2 ?
thz
note the ans is expressed in terms of Vw and Vm
thanks a lot
relative velocity
2009-09-30 5:48 am
回答 (1)
2009-09-30 6:17 am
✔ 最佳答案
To swim across the river, the river flow is independent to the journey of the man.By d = Vmt1
t1 = d/Vm ... (1)
For the man to swim down the river,
The relative velocity of the man to the bank
= Vm + Vw
So, d = (Vm + Vw)t2
t2 = d/(Vm + Vw)
t1 : t2 = (Vm + Vw)/ Vm
參考: Physics king
收錄日期: 2021-04-19 15:25:26
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