River Current Speed: 2m/s or 4m/s?

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SUMMARY

The current speed of the river is definitively 2m/s, as derived from the equations based on Shareen's boat speeds. When traveling upstream, the effective speed is 8m/s, and downstream it is 12m/s. By setting up the equations x + b = 12m/s and b - x = 8m/s, where x is the current speed and b is the boat speed, the solution confirms that the current speed is 2m/s. The debate regarding a potential current speed of 4m/s is resolved through algebraic verification, establishing 2m/s as the accurate answer.

PREREQUISITES
  • Understanding of basic algebraic equations
  • Knowledge of speed, distance, and time relationships
  • Familiarity with upstream and downstream motion concepts
  • Ability to solve linear equations
NEXT STEPS
  • Study the principles of relative motion in fluid dynamics
  • Learn how to set up and solve linear equations in physics problems
  • Explore the effects of current on boat navigation
  • Investigate real-world applications of speed calculations in boating
USEFUL FOR

Students in physics courses, educators teaching motion concepts, and anyone interested in understanding the dynamics of boat navigation in rivers.

Krystan
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Homework Statement



Shareen finds that when she drives her motorboat upstream she can travel with a speed of only 8m/s, while she moves with a speed of 12m/s when she heads downstream. What is the current of the river on which Shareen is traveling?


The Attempt at a Solution



x= current speed
b= boat speed

x+b= 12m/s
b-x= 8m/s
b=x+8
x+x+8= 12
2x= 4
x=2

12m/s-8m/s=4m/s

Our physics class is having a debate on whether the answer is 2m/s or 4m/s and why.
 
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I agree with your first answer, for reasons the algebra suggests. Maybe solve for the boat speed in either case? It will likely be inconsistent at 4m/s.
 

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