River Flow Rate: Find Answer b in 1.5m/s at 28°

[ChloeYip]

Homework Statement

You want to swim straight across a river that is 76 m wide. You find that you can do this if you swim at an angle of θ = 28° from the upstream direction at a constant rate of 1.5 m/s relative to the water. At what rate does the river flow? The angle θ is measured from the river bank (directly upstream is θ = 0° while directly across the river is θ = 90°).
(a) 1.8 m/s (b) 1.3 m/s (c) 1.6 m/s (d) 0.70 m/s (e) 2.1 m/s

Answer:b

Homework Equations

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The Attempt at a Solution

1.5 sin28° = 0.70m/s

How can obtain answer b?

Thanks

 

[gneill]

How did you formulate your solution attempt? Did you make a sketch? If so, can you share it?

 

[ChloeYip]

Oh thanks...
I just discover my drawing is wrong...
The answer is by v cos theta

 

[gneill]

Oh thanks...
I just discover my drawing is wrong...
The answer is by v cos theta

Okay! It's great that you worked it out yourself!