Math Problem Statement

Flying to Kampala with a tailwind, a plane averaged 158 km/h. On the return trip, the plane only averaged 112 km/h while flying back into the same wind. Find the speed of the wind.

Solution

We can solve this problem by setting up a system of equations based on the relationship between speed, time, and distance.

Step 1: Define variables

  • Let the speed of the plane in still air be pp km/h.
  • Let the speed of the wind be ww km/h.

Step 2: Use the information given

On the flight to Kampala (with a tailwind):

  • The plane’s speed relative to the ground is the sum of the speed of the plane in still air and the speed of the wind: Speed to Kampala=p+w=158 km/h.\text{Speed to Kampala} = p + w = 158 \text{ km/h}.

On the return trip (with a headwind):

  • The plane’s speed relative to the ground is the difference between the speed of the plane in still air and the speed of the wind: Speed back=pw=112 km/h.\text{Speed back} = p - w = 112 \text{ km/h}.

Step 3: Set up the system of equations

We now have the following system of two equations: p+w=158(1)p + w = 158 \quad \text{(1)} pw=112(2).p - w = 112 \quad \text{(2)}.

Step 4: Solve the system of equations

Add equations (1) and (2) to eliminate ww: (p+w)+(pw)=158+112,(p + w) + (p - w) = 158 + 112, 2p=270,2p = 270, p=2702=135 km/h.p = \frac{270}{2} = 135 \text{ km/h}.

Now, substitute p=135p = 135 into equation (1) to find ww: 135+w=158,135 + w = 158, w=158135=23 km/h.w = 158 - 135 = 23 \text{ km/h}.

Final Answer:

The speed of the wind is 23 km/h.

Would you like further clarification on any of the steps? Here are some additional questions related to this problem:

  1. How would the result change if the plane had an even higher speed in still air?
  2. What would happen if the wind speed were to increase significantly?
  3. How can we apply this method to solve similar problems with different distances or speeds?
  4. How would the time for each trip change if the wind speed were different?
  5. What are some real-world scenarios where these types of calculations are applied?

Tip: To solve problems involving relative motion (like this one), always break down the motion in terms of the speed relative to the ground and the object’s speed in still air.

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Math Problem Analysis

Mathematical Concepts

Algebra
Systems of Equations
Relative Motion

Formulas

Speed with tailwind: p + w
Speed with headwind: p - w
Solving systems of equations: Substitution or elimination method

Theorems

Basic System of Equations Theorem

Suitable Grade Level

Grades 8-10