4.1 Turning effect of force

• Moment of a force about a point
• Principle of moments
• Moments of anti-parallel forces (couples)
• Applications of the turning effect of force in real life

• determine the moment of a force at a point
• calculate the moments of anti-parallel forces using a formula
• apply the turning effect of force in real life situations
• appreciate the importance of the turning effect of force in everyday life

“How is the turning effect of force important in daily life?”

“Why is a door handle fitted as far as possible from the hinges?”

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1. The turning effect of a force
   40 min · 2 practice tasks · quiz
   Why where you push matters as much as how hard, and the rule that keeps a see-saw level.
2. Anti-parallel forces and everyday applications
   40 min · 2 practice tasks · quiz
   The pair of forces that turns without pushing, and the turning effect at work all around you.
3. Perpendicular distance when the force is at an angle
   40 min · 1 practice tasks · quiz
   The distance in M = F x d is never the length of the handle unless you push at right angles.
4. Clockwise and anticlockwise moments
   40 min · 1 practice tasks · quiz
   Moments in the same sense add. Equilibrium is when the two totals cancel.
5. Verifying the principle of moments
   40 min · 1 practice tasks · quiz
   A fair metre-rule experiment, and why the rule must be balanced empty before any masses go on.
6. Centre of gravity and the weight of the beam
   40 min · 1 practice tasks · quiz
   A uniform beam's weight acts at its midpoint; shift the pivot and that weight suddenly matters.
7. Like and unlike parallel forces
   40 min · 1 practice tasks · quiz
   How parallel forces add or subtract, and where their single equivalent force must sit.
8. Three classes of lever
   40 min · 1 practice tasks · quiz
   Name a lever by what sits in the middle, then read effort and load from the two distances.
9. Stability and overturning
   40 min · 1 practice tasks · quiz
   A body topples when the line of its weight falls outside the base. Wide and low is stable.
10. Solving mixed moment problems
    40 min · 1 practice tasks · quiz
    Choose a pivot that kills an unknown, keep units consistent, then check with forces.
11. The turning effect at work in Kenya
    40 min · 1 practice tasks · quiz
    Tools, vehicles, the port and the workshop: moments as a safety and design habit.