How to Calculate Rowing Speed and Direction to Reach a Boathouse?

Click For Summary
SUMMARY

The discussion focuses on calculating the rowing speed and direction needed to reach a boathouse located 14 m downstream while crossing an 82 m wide river with a current of 0.50 m/s. To reach the destination in 2 minutes, the required upstream rowing speed is 0.38333 m/s, and the speed across the river is 0.68333 m/s. The resultant speed calculated using the Pythagorean theorem is approximately 0.7835 m/s, with a rowing angle of 60.7 degrees upstream. The relative velocity equation VBE = VBW + VWE is crucial for understanding the relationship between the boat's velocity, the water's velocity, and the resultant velocity.

PREREQUISITES
  • Understanding of relative velocity concepts
  • Knowledge of vector addition and the Pythagorean theorem
  • Familiarity with basic trigonometry, specifically arctangent
  • Ability to perform unit conversions and time calculations
NEXT STEPS
  • Study the principles of relative velocity in fluid dynamics
  • Learn how to apply the Pythagorean theorem in vector calculations
  • Explore trigonometric functions and their applications in navigation
  • Investigate real-world applications of rowing and water navigation techniques
USEFUL FOR

Students studying physics, particularly in mechanics and fluid dynamics, as well as outdoor enthusiasts and navigators interested in optimizing rowing techniques across currents.

ECard
Messages
1
Reaction score
0

Homework Statement



You wish to paddle a boat across an 82 m wide river and land at a boathouse that is 14 m downstream of your starting point. If the current in the river is uniform at 0.50 m/s, how fast and in what direction do you need to row to reach the boathouse in 2.0 minutes?

Homework Equations


Relative Velocity equation
VBE = VBW + VWE

The Attempt at a Solution


[/B]
I know that in 2 minutes I would end up 60 m downstream.
(120 s)(0.50 m/s) = 60 m

This is 60 - 14 = 46 m away from the boathouse

Which means that I would need to row upstream at
46 m / 120 s = .38333 m/s
And row across the water at a speed of
82 m / 120 s = .68333 m/s
to be able to reach my destination in 2 min.

From this I'm assuming that I can use Pythagorean equation to solve for the resultant vector.
sqrt[(46m/120s)2 + (82m/120s)2] = .78351061 m/s

And then the angle of direction through trig
theta = arctan( (82m/120s) / (46m/120s) ) = 60.7 degrees upstream and across

I'm not sure if this is right because from the equation I get that
VWE = 0.50 m/s
 
Physics news on Phys.org
I think your answer is correct. But I don't understand your last line :
"I'm not sure if this is right because from the equation I get that
VWE = 0.50 m/s"

And in your relative velocity equation , I don't get what does that "W" represent.
 

Similar threads

  • · Replies 9 ·
Replies
9
Views
2K
  • · Replies 9 ·
Replies
9
Views
7K
  • · Replies 4 ·
Replies
4
Views
2K
Replies
6
Views
2K
  • · Replies 29 ·
Replies
29
Views
4K
Replies
2
Views
1K
Replies
1
Views
2K
  • · Replies 6 ·
Replies
6
Views
4K
  • · Replies 1 ·
Replies
1
Views
3K
  • · Replies 3 ·
Replies
3
Views
3K