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Stability of an object

Stability of an object

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Stability of an object

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  1. Stability of an object Science Form 2 FIS CIE Year 8A & YF 3rd Term, 2011/2012

  2. Centre of Gravity • This is the point at which the whole weight of the body can be taken as acting through

  3. Regular and uniform objects • The geometrical centre of some common shapes • This is also where the centre of gravity and the object’s weight, W, can be considered to act W W W

  4. For non-uniform shapes • When more than one material makes up an object the centre of gravity will be affected. W W

  5. For non-uniform shapes • When more than one material makes up an object the centre of gravity will be affected. W

  6. External CG • For some objects the CG is not located on the actual object Stool Ring 2 uniform perpendicular planks W W W This happens when the planks are of unequal masses. Which do you think is more massive, kids?

  7. When an object is suspended • When an object is suspended, so that it can swing freely, it will come to rest with its CG vertically below the point of suspension

  8. CG of an irregular shape • Find the CG of an irregular shaped lamina Pin held by clamp b c a a b c c b a hole plumb line

  9. Balancing Act! • Now, try to balance the object at that point… c a b

  10. Stability • An object is stable if it can return to its original position when tilted and released • An object is unstable if it cannot return to its original position when tilted and released

  11. The Traffic Cone • A great example of a VERY stable object. • What features of the cone make it so stable? • Low Centre of Gravity • Wide base

  12. Factors that affect stability • The position of the Centre of Gravity • The Base Area

  13. Factors that affect stability • The position of the Centre of Gravity • The Base Area

  14. Factors that affect stability • The position of the Centre of Gravity • The Base Area

  15. Improving STABILITY • Lowering the Centre of Gravity • Increasing the Base Area

  16. The Double Decker Bus • Each of the diagrams on the right represent a Double Decker bus with passengers inside. • Draw out and label the one which shows all passengers on • the lower level • the upper level • both levels

  17. Delete a word to complete the sentences • If more people sit upstairs on the bus, the CG will rise/fall.This will make the bus more stable/unstableand itcan be tilted by a greater/lesser angle • The bus will fall over when the CG acts inside/outside of the bus’ base • A stable object has a low/highCG and a narrow/wide base

  18. Activity Time • Pair • Do Activity 9.3 in your textbook • Complete the worksheets [will be given to each pair]