The weight of an object lies at the ............

Options

A. Centre of mass
B. Centre of buoyancy
C. Centre of gravity
D. Geometric centre always

Explanation

To solve the question regarding where the weight of an object lies, we will analyze the options provided and clarify the concepts involved.

### Step-by-Step Solution:

1. **Understanding Weight and Mass**:
- Weight is the force exerted by gravity on an object and is dependent on the object's mass and the acceleration due to gravity. It is calculated using the formula:
\[ \text{Weight} (W) = \text{Mass} (m) \times \text{Acceleration due to gravity} (g) \]

2. **Identifying Key Terms**:
- **Center of Mass**: This is the point where the mass of an object is considered to be concentrated. It is the average position of all the mass in the object.
- **Center of Gravity**: This is the point where the total weight of the object can be considered to act. For uniform gravitational fields, the center of gravity coincides with the center of mass.
- **Center of Buoyancy**: This is the center of mass of the displaced fluid when an object is submerged in a fluid.
- **Geometric Center**: This is the average position of all points in a shape, which may not correspond to the center of mass or center of gravity.

3. **Analyzing the Options**:
- **Option 1: Center of Mass**: This is relevant for mass, not weight.
- **Option 2: Center of Buoyancy**: This pertains to fluid mechanics and is not relevant to weight.
- **Option 3: Center of Gravity**: This is where the weight of the object acts, especially in a uniform gravitational field.
- **Option 4: Geometric Center**: This does not necessarily relate to weight or mass.

4. **Conclusion**:
- Since the question specifically asks about the weight of an object, the correct answer is **Option 3: Center of Gravity**. The weight of an object lies at its center of gravity.

### Final Answer:
The weight of an object lies at the **center of gravity**.

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