Math Problem Statement

Ayana and Ashton are in canoes along a stretch of the DesPlaines River. They typically paddle at the same pace and can travel at the same speed as one another (relative to the water). But Ayana heads upstream while Ashton heads downstream. We will define the positive direction as downstream. An observer on the shore observes that Ayana has a velocity of -1.03 m/s and Ashton has a velocity of +2.81 m/s. What is the river velocity? That is, what is the velocity of the water relative to the shore?

Solution

To determine the velocity of the river (i.e., the water velocity relative to the shore), we can utilize the given velocities of Ayana and Ashton, as well as the fact that their paddling speed relative to the water is the same.

Problem Breakdown:

  • Ayana's velocity relative to the shore is given as 1.03m/s-1.03 \, \text{m/s} (since she is paddling upstream).
  • Ashton's velocity relative to the shore is given as +2.81m/s+2.81 \, \text{m/s} (since he is paddling downstream).
  • Their speed relative to the water (paddling speed) is the same, which means:
    • Ayana's velocity relative to the shore is the result of her paddling speed relative to the water subtracted by the river's velocity.
    • Ashton's velocity relative to the shore is the result of his paddling speed relative to the water added to the river's velocity.

Let’s define:

  • vriverv_{\text{river}} = the velocity of the river relative to the shore.
  • vpaddlev_{\text{paddle}} = their paddling speed relative to the water (the same for both Ayana and Ashton).

We can write two equations based on the observations:

  1. vAyana=vpaddlevriverv_{\text{Ayana}} = v_{\text{paddle}} - v_{\text{river}}, where vAyana=1.03m/sv_{\text{Ayana}} = -1.03 \, \text{m/s}
  2. vAshton=vpaddle+vriverv_{\text{Ashton}} = v_{\text{paddle}} + v_{\text{river}}, where vAshton=2.81m/sv_{\text{Ashton}} = 2.81 \, \text{m/s}

Step-by-Step Solution:

  1. Add the two equations to eliminate vpaddlev_{\text{paddle}}: (1.03)+2.81=(vpaddlevriver)+(vpaddle+vriver)(-1.03) + 2.81 = (v_{\text{paddle}} - v_{\text{river}}) + (v_{\text{paddle}} + v_{\text{river}}) Simplifying: 1.78=2vpaddle1.78 = 2v_{\text{paddle}} vpaddle=1.782=0.89m/sv_{\text{paddle}} = \frac{1.78}{2} = 0.89 \, \text{m/s}

  2. Now, substitute vpaddlev_{\text{paddle}} into one of the original equations to solve for vriverv_{\text{river}}. Using the equation for Ayana: 1.03=0.89vriver-1.03 = 0.89 - v_{\text{river}} Solving for vriverv_{\text{river}}: vriver=0.89+1.03=1.92m/sv_{\text{river}} = 0.89 + 1.03 = 1.92 \, \text{m/s}

Final Answer:

The velocity of the river relative to the shore is 1.92m/s1.92 \, \text{m/s} downstream.

Would you like further details, or do you have any questions about the solution?

Here are 5 related questions:

  1. How would the velocities change if both Ayana and Ashton were paddling at different speeds?
  2. What if Ayana paddled faster than Ashton; how would that affect the equations?
  3. How do upstream and downstream velocities typically affect the travel times of boats?
  4. Can we determine the time it takes for either paddler to cover a certain distance if we know their paddling speed relative to the water?
  5. How would the problem change if the river's current varied along its path?

Tip: When analyzing relative velocities, always clearly define the reference frame (such as "relative to the shore" or "relative to the water"). This helps in setting up the correct equations.

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Math Problem Analysis

Mathematical Concepts

Relative Velocity
Linear Equations

Formulas

v_Ayana = v_paddle - v_river
v_Ashton = v_paddle + v_river
v_paddle = (v_Ashton - v_Ayana) / 2

Theorems

Equation of Motion in One Dimension
Relative Motion Theorem

Suitable Grade Level

Grades 9-12