A uniform half metre rule balances horizontally on a knife edge at 29 cm mark when a weight of 20 gf is suspended from one end.
What is the weight of the half metre rule ?

Explanation

To solve the problem, we need to find the weight of the half-meter rule (let's denote it as \( W \)). The rule balances horizontally at the 29 cm mark when a weight of 20 gf is suspended from one end (the 50 cm mark).

### Step-by-Step Solution:

1. **Identify the Setup**:
- The half-meter rule is 50 cm long.
- The knife edge is at the 29 cm mark.
- A weight of 20 gf is suspended at the 50 cm mark.
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