Why is it easier to swim in sea water than in the river water ?

Explanation

To understand why it is easier to swim in sea water than in river water, we need to consider the concept of density and buoyancy.

### Step-by-Step Solution:

1. **Understanding Density**:
- Density is defined as mass per unit volume. It is a measure of how much matter is packed into a given space.
- The density of sea water is approximately 1040 kg/m³, while the density of river water is about 1000 kg/m³.

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