the centre of gravity of a body on the earth coincides with its centre of mass for a small object whereas for an extended object it may not ,what is the qualitaitve meaning of small and extended in this regard ?
for which of the following two coincides ? A building , a pond , a lake ,a mountain ?

Explanation

To solve the question, we need to understand the concepts of the center of mass (COM) and the center of gravity (COG) and how they relate to small and extended objects.

### Step-by-Step Solution:

1. **Define Center of Mass (COM) and Center of Gravity (COG)**:
- The **Center of Mass** is an imaginary point in a body where the total mass can be considered to be concentrated. It is determined by the distribution of mass in the object.
- The **Center of Gravity** is the point in a body where the total weight of the body acts. It depends on the gravitational field acting on the body.

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