Bobo, the clown, can swim at 2.0 m/s. he must make a landing directly across to the north side of the styx river, which is 100.
m wide. the river flows at 6.0 m/s due east at this point. bobo’s biggest problem is that he can only swim while facing due north. how can he possibly make a landing at the desired location?
Bobo's swimming speed = 2.0 m/s Width of the river = 100 m Flowrate of the river = 6.0 m/s due east
First, we need to illustrate the problem. Draw the river with a width of 100 meters. Then, the flow of the river, east at 6 meters per second. Lastly, draw Bobo at one side of the river facing north and an arrow representing swimming speed at 2 meters per second.
Now, we can use the Pythagorean theorem to solve this rate problem.
c^2 = a^2 + b^2
c = speed of Bobo needed a = speed of Bobo facing north b = flow rate of the river going east
c^2 = 2^2 + 6^2
c = 6.32 m / s should be his speed to overcome the current and make a landing at the desired location.
When light passes from a less dense to a more dense substance, (for example passing from air into water), the light is refracted (or bent) towards the normal. In your question the light is moving from rarer to denser medium