If earth suddenly contracts by 1/2 of its present radius by how much would the day be decreased ?

Explanation

To solve the problem of how much the day would be decreased if the Earth suddenly contracts to half of its present radius, we can follow these steps:

### Step 1: Understand the conservation of angular momentum
When the Earth contracts, its mass remains the same, but its radius changes. Because no external torque is acting on the Earth, we can apply the principle of conservation of angular momentum. This means that the initial angular momentum (Li) must equal the final angular momentum (Lf).

### Step 2: Write the expressions for angular momentum
The angular momentum (L) of a rotating body can be expressed as:
\[ L = I \cdot \omega \]
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