A parrot sitting on the floor of a wire cage which is being carried by a boy, starts flying. The boy will feel that the box is now

Options

A. heavier
B. lighter
C. same in weight
D. lighter in the beginning and heavier later

Answer

To solve the problem, we need to analyze the situation of the parrot flying inside the cage and how it affects the weight that the boy feels while carrying the cage.

### Step-by-Step Solution:

1. **Identify the Weights:**
- Let \( P \) be the weight of the parrot.
- Let \( C \) be the weight of the cage.

2. **Weight When the Parrot is at Rest:**
- When the parrot is sitting on the floor of the cage, the total weight that the boy feels is the sum of the weights of the parrot and the cage:
\[ \text{Total Weight} = P + C \]

3. **Weight When the Parrot Starts Flying:**
- When the parrot starts flying, it exerts a force downwards on the air inside the cage, which creates an upward lift. However, since the parrot is no longer in contact with the floor of the cage, the normal force that the cage exerts on the parrot is removed.
- The boy will now only feel the weight of the cage, as the parrot's weight is not being transmitted to the cage anymore. Thus, the total weight that the boy feels now becomes:
\[ \text{Total Weight} = C \]

4. **Comparison of Weights:**
- Initially, when the parrot was sitting, the boy felt \( P + C \).
- After the parrot starts flying, the boy feels \( C \).
- Since \( P > 0 \), it follows that:
\[ P + C > C \]
- Therefore, the boy will feel that the cage is lighter when the parrot starts flying.

5. **Conclusion:**
- The boy will feel that the cage is now **lighter**.

### Final Answer:
The boy will feel that the box is now **lighter**.

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