# Moments

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• Created by: Sophie
• Created on: 04-05-13 10:50
• Turning Forces and the Centre of Mass
• A moment is the turning effect of a force
• Moment= force x perpendicular distance from line of action to pivot
• E.g spanner
• Force on spanner causes turning effect on the nut (pivot).
• A larger force means a larger moment
• Longer spanner
• Same force can exert a larger moment bacause the perpendicular distance from the pivot is larger
• To get the maximum moment you need to push at right angles (perpendicular) to the spanner
• Centre of mass
• Hangs directly below point of suspension
• Centre of mass= the point at which the whole mass is concentrated
• Suspend a shape and plumb line from the same point and wait until the stop moving
• Draw a line along the plumb line
• Do the same thing again, but suspend the shape from a different pivot point
• The centre of mass is where your two lines cross
• In symmetircal shapes you can guess by looking for lines of symmetry
• The object's weight acts at a distance from the pivot, which creates a moment about the pivot
• This makes is swing until the centre of mass is at its lowest
• It rests in this position because there is no moment- the pivot is in line with the line of action of the force