consider a boat can travel with V speed in still water which trips elapsed time will

W

WadeH

New member
be least ? a)a boats travle a distance 2d in still water
b)boat travles a distance d upstream and then returns to its starting point
c)boat travles distance d downstream and then returns to its starting point
d)the time is the same in all the above cases
 
A

AlgebratNinja

New member
The answer is a.

Try a numeric example to prove this to yourself. The velocity vectors of the boat and the water add together.

Say for example the boat travels 10m/s and the water flows at 5m/s.
Use t=d/v to figure out the time it takes for a 1000m trip each way. Upstream v = 5m/s, so t=1000m/5m/s= 200s
Still water v = 10 m/s so t= 1000m/10m/s = 100s
Downstream v = 15 m/s so t = 1000m/15m/s = 66.66s

Now for the round trip:
Still water = 100s + 100s = 200s
Up/Down = 200s + 66.66 = 266.66s
Dn/Up = 66.66s + 200s = 266.66s
 
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