Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: I Need Helppp!

  1. Sep 14, 2004 #1
    A swimmer wants to cross a river, from point A to point B. The distance (from A to C) is 200 m, the distance (from C to B) is 150 m, and the speed of the current in the river is 5 km/h. Suppose that the swimmer makes an angle of (0.785 radians) with respect to the line from A to C, as indicated in the figure.
  2. jcsd
  3. Sep 14, 2004 #2
    how the heck do I start???
  4. Sep 14, 2004 #3


    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    Represent the velocity of the rivers current and the velocity of the swimmer as vectors, use vector addition to find the sum. Drawing a picture helps.

    In the future post homework questions in the homework forum.
  5. Sep 14, 2004 #4


    User Avatar
    Science Advisor
    Gold Member

    Insufficient information. What are you solving for, distance from A to B? It sounds like a triangulation problem. The relevance of the river current speed is also unclear since no swim speed is given. If it is assumed the swimmer will arrive at point B given the swim speed, current speed, and initial angle of approach, the problem can be solved by finding the vector angle of the swimmer's path - since you will then have 2 sides and an angle of a triangle.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook