1. **Problem statement:** A girl uses a spanner of length 20 cm and pulls at right angles with a force of 50 N. We need to calculate the moment of her pull. 2. **Understanding the moment:** Moment (torque) is calculated using the formula $$\text{Moment} = \text{Force} \times \text{Perpendicular distance}$$ from the point of rotation. 3. **Convert length to meters:** Length of the spanner $$= 20\text{ cm} = \frac{20}{100} = 0.2\text{ m}$$. 4. **Calculation:** $$\text{Moment} = 50 \text{ N} \times 0.2 \text{ m} = 10 \text{ Nm}$$. 5. **Answer:** The moment of her pull is $$10 \text{ Nm}$$.