Concept: A moment is the turning force around a fixed pivot.
Examples:
A spanner loosening a fixed nut.
A child on a seesaw.
A door opening around a hinge.
Key Concepts
Pivot: The fixed point around which turning occurs, such as:
Nut (for a spanner)
Middle of the seesaw
Hinge (for a door)
Equilibrium: When moments are equal and opposite, the system is balanced.
Calculating Moments
Formula: Moment = Force x Distance
Units: Moments are measured in newton-meters (N*m).
Force is in newtons (N).
Distance is in meters, specifically the perpendicular distance from the pivot to the force.*
Example Problem: Seesaw
Scenario: Balancing a seesaw with two children of different weights.
Calculation:
Lighter Child: 500 N x 2 m = 1000 N*m
Heavier Child: 1000 N x 1 m = 1000 N*m
Outcome: Perfect balance achieved with equal moments.
Additional Examples
Woman Tightening a Wheel Nut:
Calculate moment: 3 Nm (note conversion from 30 cm to meters).
Formula Triangle for Moments
Formulas:
Force = Moment / Distance
Distance = Moment / Force
Moment = Force x Distance
Considerations for Calculations
Clockwise and Anti-Clockwise Moments:
For balance: Clockwise moments = Anti-clockwise moments
Summary
Moments are crucial in understanding the mechanics of turning forces.
Proper balance is achieved through equal and opposite moments, calculated as force times the perpendicular distance from the pivot. Moments are expressed in newton-meters.