Copyright © Michael Richmond.
This work is licensed under a Creative Commons License.
The bed of a river of width D is dry, so that you can walk across it. Two islands stick up out of the river bed -- one is directly downstream from the other, separated from the first by the same distance D.
Suppose that you walk at a speed of v. How long will it take to walk from A on the left bank to B on the right bank?
____________________How long will it take to walk back, from B to A?
____________________How long will it take to make the round trip?
____________________
Now, suppose you start on island X and walk to the other island, Y. How long will that take?
____________________How long will it take to walk back, from Y to X?
____________________How long will it take to make the round trip?
____________________
Plug in some numbers: suppose that D = 2 km, v = 1 m/s, and u = 0.1 m/s. What are the times required for the two round trips?
____________________ vs. _________________
Copyright © Michael Richmond.
This work is licensed under a Creative Commons License.