A cage of 1.5 kg carries a bird of 2.5 kg inside it. When the bird starts flying inside the cage, the weight of bird and cage assembly is

Options

A. 4 kg
B. 1.5 kg
C. 2.5 kg
D. 2.0 kg

Explanation

To solve the problem, we need to determine the total weight of the bird and cage assembly when the bird is flying inside the cage.

### Step-by-Step Solution:

1. **Identify the Masses**:
- The mass of the cage (m_cage) = 1.5 kg
- The mass of the bird (m_bird) = 2.5 kg

2. **Calculate the Total Mass**:
- The total mass of the bird and cage assembly is the sum of the mass of the cage and the mass of the bird.
\[ \text{Total Mass} = m_{\text{cage}} + m_{\text{bird}} = 1.5 \, \text{kg} + 2.5 \, \text{kg} = 4.0 \, \text{kg} \]

3. **Understand the Concept of Weight**:
- Weight is the force due to gravity acting on an object. It can be calculated using the formula:
\[ \text{Weight} = \text{Mass} \times g \]
where \( g \) is the acceleration due to gravity (approximately \( 9.81 \, \text{m/s}^2 \)).

4. **Calculate the Weight of the Assembly**:
- Since the total mass of the bird and cage assembly is 4.0 kg, the weight can be calculated as:
\[ \text{Weight} = 4.0 \, \text{kg} \times 9.81 \, \text{m/s}^2 = 39.24 \, \text{N} \]

5. **Conclusion**:
- The weight of the bird and cage assembly remains the same whether the bird is flying inside the cage or not because the system is closed and the forces acting on it are balanced. Thus, the total weight of the assembly is 4.0 kg.

### Final Answer:
The weight of the bird and cage assembly is **4.0 kg**.

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