Optimizing River Crossing Velocity Vectors

In summary, the problem involves a swimmer trying to cross a river from point A to point B, with distances d1=185m and d2=141m, and a current speed of 5.00 km/h. The swimmer's velocity relative to the water makes an angle of 36.0 degrees with the line from A to C. The conversation includes three questions regarding the angle between the swimmer's velocity vector and the riverbank, the angle between the swimmer's velocity vector relative to the water and the velocity vector relative to a stationary observer, and the desired speed (u_s) of the swimmer relative to the water to directly swim from A to B. The law of sines may be used to
  • #1
EthanFBM
2
0

Homework Statement


A swimmer wants to cross a river, swimming directly from point A to point B, as shown in the figure. The distance d_1 (from A to C) is 185 m, the distance d_2 (from C to B) is 141 m, and the speed v_r of the current in the river is 5.00 km/h. Suppose that the swimmer's velocity relative to the water makes an angle of 36.0 degrees with the line from A to C, as indicated in the figure.

1)What is the angle between the velocity vector for the swimmer with respect to a stationary observer (i.e. an observer standing at rest on the shore) and the riverbank?

2)What is the angle between the velocity vector for the swimmer with respect to the water and the velocity vector for the swimmer with respect to a stationary observer?

3)To swim directly from A to B, what speed u_s, relative to the water, should the swimmer have? Hint: use the law of sines with the known values in your velocity vector triangle.

Homework Equations





The Attempt at a Solution


I haven't got a clue other than possibly using related vectors to solve this problem, but i can't seem to get it to work, any help would be greatly appreciated
thanks
 
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  • #2
We need the diagram or at least an explanation of where A, B and C are located.
 
  • #3
Last edited by a moderator:
  • #4
i am working on this same problem. i don't get it :(
 
  • #5
Yeah the wordings are weird.
 
  • #6
yeah mastering physics is stupid.
 

1. How can you determine the best route to swim across a river?

The best route to swim across a river can be determined by assessing the river's current and depth, as well as any obstacles, such as rocks or debris, that may be present. It is important to choose a route that minimizes the amount of time and energy needed to cross.

2. Is it safe to swim across a river?

The safety of swimming across a river depends on various factors, such as the strength of the current, the depth of the water, and the swimmer's abilities. It is important to assess these factors and exercise caution before attempting to swim across a river.

3. Can swimming across a river be used as a form of exercise?

Yes, swimming across a river can be a great form of exercise as it involves using multiple muscle groups and can also improve cardiovascular health. However, it is important to ensure that the river's conditions are safe for swimming and to have proper supervision.

4. What equipment is needed to swim across a river?

The necessary equipment for swimming across a river may vary depending on the specific conditions and distance of the swim. However, some common equipment includes a swimsuit, goggles, and possibly a flotation device or swim fins. It is also important to have a plan for getting out of the river once the swim is completed.

5. Are there any safety precautions that should be taken when swimming across a river?

Yes, there are several safety precautions that should be taken when swimming across a river, including wearing a life jacket, having a designated lookout on shore, and avoiding swimming in swift currents or areas with submerged obstacles. It is also important to have a backup plan in case of emergency and to never swim alone.

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