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Simple Machine, The centre of mass of a regularly shaped body that has the…

- - - - Neutral Equilibrium
        
        A body is in neutral equilibrium if it stays in its new position when displaced
        
        Its centre of mass does not rise or fall because there is no moment to increase or decrease the displacement.
      - Stable Equilbrium
        
        A body is in stable equilibrium if when slightly displaced and then released it returns to its previous position.
        
        Its centre of mass rises when it is displaced. It rolls back because its weight has a moment about the point of contact that acts to reduce the displacement.
      - Unstable Equilibrium
        
        A body is in unstable equilibrium if it moves further away from its previous position when slightly displaced and released.
        
        Its centre of mass falls when it is displaced slightly because there is a moment which increases the displacement.
    - - A recking horse
      - The perched parrot
      - Balancing a needle on its point
      - A self-righting toy has a heavy base and, when tilted, the weight acting through the centre of mass has a moment about the point of contact. This restores it to the upright position.
    - - Characteristic
        
        The stability of a body is therefore increased by :
        (i) lowering its centre of mass, and
        (ii) increasing the area of its base
        
        Toppling can be investigated by placing an empty can on a plank (with a rough surface to prevent slipping) which is slowly tilted. The angle of tilt is noted when the can falls over.
      - Definition
        
        The position of the centre of mass of a body affects whether or not it topples over easily.
      - A body topples when the vertical line throughvits centre of mass falls outside its base
      - Otherwise it remains stable, where the body will not topple.
- - - - When a body is in equilibrium the sum of the clockwise moments about any point equals the sum of the anticlockwise moments about the same point. There is no net moment on a body which is in equilibrium.
    - - How to balance a beam about a pivot
        
        -If the beam tends to swing clockwise, m1 can be moved further from the pivot to increase its turning effect; alternatively m2 can be moved nearer to the pivot to reduce its turning effect
        
        -the weights must be moved so that the clockwise turning effect equals the anticlockwise turning effect and the net moment on the beam becomes zero.
    - - turning effect of a force
        Formula : Moment of a force : Force x perpendicular pf the line of of action of the force from fulcrum
  - - - Spanner
      - Scissors
      - Forearm
      - Wheelbarrow
      - Crowbar