When one swims across a flowing river, maximum energy is spent in

Options

A. firsst 1/3 of the distance
B. second 1/3 of the distance
C. last 1/3 of the distance
D. equal energy is spent throughout

Answer

To solve the question of when maximum energy is spent while swimming across a flowing river, we can analyze the situation step by step.

### Step-by-Step Solution:

1. **Understanding the Scenario**:
- When a swimmer attempts to swim across a river, they are not only swimming against the current of the river but also trying to reach the opposite bank. The river's current exerts a force that the swimmer must overcome.

2. **Energy Expenditure**:
- Energy is required to overcome the resistance posed by the river's current. The swimmer needs to exert force to maintain their velocity and direction across the flow of the river.

3. **Dividing the Journey**:
- We can divide the swimmer's journey into three equal parts (one-third of the distance each). The question asks where the maximum energy is spent.

4. **First One-Third of the Distance**:
- In the first one-third of the distance, the swimmer is likely to be accelerating to reach a certain speed. This acceleration requires a considerable amount of energy as the swimmer is working against the current to establish their velocity.

5. **Second and Last One-Third of the Distance**:
- In the second one-third and the last one-third of the distance, the swimmer is likely maintaining a constant speed after having reached it in the first segment. The energy expenditure in these segments will be less compared to the first segment because they are not accelerating anymore.

6. **Conclusion**:
- Therefore, the maximum energy is spent during the first one-third of the distance as the swimmer is working to overcome inertia and the current to establish their swimming speed.

### Final Answer:
- Maximum energy is spent in the **first one-third of the distance**.

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