Using a PASCO Aluminium Metre Rule to Achieve Perfect Balance

 

Using a PASCO Aluminium Metre Rule to Achieve Perfect Balance

(Moments, Torque & a very satisfying ‘just right’ experiment)

Balancing a metre rule never fails to hook students. It looks simple, feels intuitive… and then quietly introduces one of the most important ideas in physics: moments.

Using a PASCO Scientific aluminium metre rule, a knife-edge pivot, and a selection of masses, students can see torque in action rather than just calculate it on paper.

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🔧 The Setup

• Aluminium metre rule (uniform mass)

• Knife-edge or pivot clamp

• Slotted masses

• Ruler scale clearly visible on both sides

Start by finding the centre of mass of the metre rule itself. Even with a uniform rule, students quickly learn that measured balance beats assumption.

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⚖️ The Physics Behind the Balance

The rule balances when:

Clockwise moments = Anticlockwise moments

Or, more formally:

$$\text{Force} \times \text{distance from pivot}$$

A smaller mass placed further from the pivot can balance a larger mass placed closer in — a lovely “aha” moment that sticks.

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🧪 What Students Can Explore

• Moving a fixed mass further from the pivot to regain balance

• Swapping mass and distance combinations to keep total moment constant

• Adding the mass of the metre rule itself into calculations

• Predicting positions before testing them experimentally

It’s ideal for:

• GCSE Physics (Moments, turning effects)

• A-Level Physics (Centre of mass, torque, equilibrium)

• Practical skills: planning, measuring, evaluating uncertainty

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🎥 Why This Works So Well on Camera

This is a visually perfect experiment:

• Clear cause-and-effect

• Immediate feedback

• Easy to film from above

• Brilliant for slow-motion “almost balanced” moments

In the lab or in an online lesson, students can suggest adjustments live and watch the system respond in real time.