## anonymous 4 years ago A river flows with a steady speed v. A student swims upstream a distance d and then back to the starting point.The student can swim at speed c in still water. a) In terms of d,v, and c what time interval is required for the round tip? [I put L/(d-v) + L/(d+v) + L/c dont know if that's correct] b) What time interval would be required if the water were still? Use any variable or symbol stated above necessary. c) Which time interval is larger: swimmng in still water, it will vary, simming with and against the current

1. Mertsj

|dw:1327237660925:dw|

2. Mertsj

$t=\frac{d}{c-v}+\frac{d}{c+v}$

3. Mertsj

In still water: |dw:1327237971468:dw|

4. Mertsj

$t=\frac{2d}{c}$

5. anonymous

Swimming with and against the current is ALWAYS longer because of the extra time required to swim against it, the total average speed of the swimmer (swiming with+against) is slower then the swimmer just swimming in still water