1. River Problems

2. Swimming upstream or downstream
S: Swimmer
W: Water
G: Ground
0.5 m/s
VSG= 2 – 0.5 = 1.5 m/s
VSG= = 2.5 m/s
Swimming upstream or downstream
(assume that the swimmer can swim at 2 m/s in still water)

3. (and “WANTING” to go straight across)
D’ OH!
Crossing the River
(and “WANTING” to go straight across)

4. (assume that the swimmer can swim at 4 m/s in still water)
2.65
m/s
4 m/s
5 m/s
The water slows him down … BUT, he goes straight across 
The water speeds the swimmer up …. BUT, he lands downstream 
Crossing the River
(assume that the swimmer can swim at 4 m/s in still water)

5. (assume that the swimmer can swim at 4 m/s in still water)
USE 60 = 4t to find the time needed to cross the river.  15 sec
USE d = 3(15) to find the distance the man travels downstream.
45 m
3 m/s
4 m/s
5 m/s
60 m
3 m/s
Crossing the River
(assume that the swimmer can swim at 4 m/s in still water)

6. (assume that the swimmer can swim at 4 m/s in still water)
S: Swimmer
W: Water
G: Ground
VSW = 4 m/s [A]
VWG = 3 m/s [DS]
VSG = 5 m/s [DS 53o A]
3 m/s
4 m/s
5 m/s A
US DS
53o
Crossing the River
(assume that the swimmer can swim at 4 m/s in still water)

7. (assume that the swimmer can swim at 4 m/s in still water)
USE 60 = 2.65t to find the time needed to cross the river.
t= sec
(slow, but straight)
2.65
m/s
4 m/s
60 m
Crossing the River
(assume that the swimmer can swim at 4 m/s in still water)

8. (assume that the swimmer can swim at 4 m/s in still water)
S: Swimmer
W: Water
G: Ground
VSW = 4 m/s [US 41.5o A]
VWG = 3 m/s [DS]
VSG = 2.65 m/s [A] A
US DS
2.65
m/s
4 m/s
41.5o
Crossing the River
(assume that the swimmer can swim at 4 m/s in still water)