The Principle of Moments states that, when a body is in equilibrium, the sum of the clockwise moments about a pivot is equal to the sum of the anti-clockwise moments about the same pivot.
Category: Moments of a Force
Define centre of gravity
The centre of gravity is the point which the whole weight of an object appears to act on, for any orientation of the object.
Define moment of a force
The moment of a force is the turning effect of a force, and is obtained by the product of the force and the perpendicular distance from the line of action of the force to the pivot.
Describe an experiment to determine the centre of gravity of an irregularly shaped thin plastic sheet.
a) Drill 3 small holes on the sheet, as near to the edge as possible, as far away from one another as possible.
b) Hang a plumb line from one of the holes.
c) When the sheet is stationary, trace the vertical line made by the plumb line using a marker.
d) Hang the plumb line from each of the other two holes and repeat the tracing of the lines.
e) The intersection point of the 3 traced lines is the centre of gravity of the plastic sheet.
Double-Pivot Push-up
