Successfully reported this slideshow.
We use your LinkedIn profile and activity data to personalize ads and to show you more relevant ads. You can change your ad preferences anytime.
Centre of Gravity and Stability of an object GCSE Physics
Learning Intentions <ul><li>By the end of the lesson we will be able to… </li></ul><ul><li>Understand the term  Centre of ...
Centre of Gravity <ul><li>This is the point at which the  whole weight of the body  can be taken as acting through  </li><...
Regular and uniform objects <ul><li>The geometrical centre of some common shapes- </li></ul><ul><li>This is also where the...
For a triangle <ul><li>The centre of gravity (and geometrical centre) is found by drawing a line from  the corner  to the ...
For non-uniform shapes <ul><li>When more than one material makes up an object the centre of gravity will be affected. </li...
External CoG <ul><li>For some objects the CoG is not located on the actual object - </li></ul>Ring Stool 2 uniform perpend...
Why does the object balance? <ul><li>Linked to Principle of Moments </li></ul><ul><li>When the object is suspended from a ...
Icebergs!
As these guys melt their CoG changes and they roll over!
 
Learning Intentions <ul><li>By the end of the lesson we will be able to… </li></ul><ul><li>Understand the term  Centre of ...
When an object is suspended <ul><li>When an object is suspended, so that it can swing freely, it will come to rest  with i...
CoG of an irregular shape <ul><li>Find the CoG of an irregular shaped lamina </li></ul>a b c a b c b a c plumb line hole P...
Balancing Act! <ul><li>Now, try to balance the object at that point… </li></ul><ul><li>Question- explain in terms of momen...
Example <ul><li>1 m long spade balances in a string loop when the loop is 30 cm from the end of the blade.  </li></ul><ul>...
Learning Intentions <ul><li>By the end of the lesson we will be able to… </li></ul><ul><li>Recall how the  stability  of a...
Position of Centre of Gravity Put these in order of STABILITY 1 2 3 4
Stability <ul><li>An object will be in  STABLE EQUILIBRIUM  when it returns to its  original position  after given a  smal...
Page 53 <ul><ul><li>Neutral Equilibrium </li></ul></ul><ul><ul><li>Unstable Equilibrium </li></ul></ul>
Stability <ul><li>For an object to start rotating it needs to have an  unbalanced moment  acting on it- </li></ul>W W W St...
<ul><li>An object becomes  unstable  when its Centre of Gravity falls  outside  of the object’s base. </li></ul><ul><li>Wh...
The Traffic Cone <ul><li>A great example of a VERY stable object. </li></ul><ul><li>What features of the cone make it so s...
Balance and Sport
Balance and Sport
Balance and Sport
The Double Decker Bus <ul><li>Each of the diagrams on the right represent a Double Decker bus with passengers inside. </li...
Delete a word to complete the sentences <ul><li>If more people sit upstairs on the bus the CoG will  rise/fall.  This will...
Question Time <ul><li>Page 56 </li></ul><ul><li>Questions 37-39 </li></ul>
Upcoming SlideShare
Loading in …5
×

Centre of Gravity and Stability

159,764 views

Published on

GCSE Physics double award notes

Published in: Education

Centre of Gravity and Stability

  1. 1. Centre of Gravity and Stability of an object GCSE Physics
  2. 2. Learning Intentions <ul><li>By the end of the lesson we will be able to… </li></ul><ul><li>Understand the term Centre of Mass/Gravity (CoG) </li></ul><ul><li>Recognise the factors that affect an object’s CoG </li></ul><ul><li>Investigate how to find the CoG of an irregular object. </li></ul>
  3. 3. Centre of Gravity <ul><li>This is the point at which the whole weight of the body can be taken as acting through </li></ul><ul><li>or </li></ul><ul><li>the point from which the object will balance </li></ul>
  4. 4. Regular and uniform objects <ul><li>The geometrical centre of some common shapes- </li></ul><ul><li>This is also where the centre of gravity and the object’s weight, W , can be considered to act </li></ul>W W W
  5. 5. For a triangle <ul><li>The centre of gravity (and geometrical centre) is found by drawing a line from the corner to the opposite line’s midpoint </li></ul>W W W
  6. 6. For non-uniform shapes <ul><li>When more than one material makes up an object the centre of gravity will be affected. </li></ul>
  7. 7. External CoG <ul><li>For some objects the CoG is not located on the actual object - </li></ul>Ring Stool 2 uniform perpendicular planks W W W
  8. 8. Why does the object balance? <ul><li>Linked to Principle of Moments </li></ul><ul><li>When the object is suspended from a point it will come to rest when the clockwise moment is equal to the anti clockwise moment </li></ul>The Humble metre rule Anti- Clockwise Moment = Clockwise Moment
  9. 9. Icebergs!
  10. 10. As these guys melt their CoG changes and they roll over!
  11. 12. Learning Intentions <ul><li>By the end of the lesson we will be able to… </li></ul><ul><li>Understand the term Centre of Mass/Gravity (CoG) </li></ul><ul><li>Recognise the factors that affect an object’s CoG </li></ul><ul><li>Investigate how to find the CoG of an irregular object. </li></ul>
  12. 13. When an object is suspended <ul><li>When an object is suspended, so that it can swing freely, it will come to rest with its CoG vertically below the point of suspension </li></ul>See Page 52 and 53 for extra notes in the book
  13. 14. CoG of an irregular shape <ul><li>Find the CoG of an irregular shaped lamina </li></ul>a b c a b c b a c plumb line hole Pin held by clamp
  14. 15. Balancing Act! <ul><li>Now, try to balance the object at that point… </li></ul><ul><li>Question- explain in terms of moments why the object can be balanced at this point? </li></ul>a b c Answer- on one side of the point of CoG, the object’s weight is causing a turning effect. This is counter balanced on the other side where the weight is causing a turning effect in the opposite direction.
  15. 16. Example <ul><li>1 m long spade balances in a string loop when the loop is 30 cm from the end of the blade. </li></ul><ul><li>A 2 kg mass is placed at the handle and the balance point is at the centre of the spade. </li></ul><ul><li>What is the mass of the spade? </li></ul>2 kg
  16. 17. Learning Intentions <ul><li>By the end of the lesson we will be able to… </li></ul><ul><li>Recall how the stability of an object depends on the… </li></ul><ul><ul><li>position of the centre of gravity </li></ul></ul><ul><ul><li>size of the object’s base </li></ul></ul>
  17. 18. Position of Centre of Gravity Put these in order of STABILITY 1 2 3 4
  18. 19. Stability <ul><li>An object will be in STABLE EQUILIBRIUM when it returns to its original position after given a small displacement </li></ul>
  19. 20. Page 53 <ul><ul><li>Neutral Equilibrium </li></ul></ul><ul><ul><li>Unstable Equilibrium </li></ul></ul>
  20. 21. Stability <ul><li>For an object to start rotating it needs to have an unbalanced moment acting on it- </li></ul>W W W Stable Pivot Pivot Rotates Clockwise Rotates Anti-Clockwise Stable Unstable
  21. 22. <ul><li>An object becomes unstable when its Centre of Gravity falls outside of the object’s base. </li></ul><ul><li>Why? </li></ul><ul><li>All of the object’s weight can be considered as acting through the CoG. If this acts outside the base then it will cause a turning effect or a moment </li></ul>
  22. 23. The Traffic Cone <ul><li>A great example of a VERY stable object. </li></ul><ul><li>What features of the cone make it so stable? </li></ul><ul><li>Low Centre of Gravity </li></ul><ul><li>Wide base </li></ul>
  23. 24. Balance and Sport
  24. 25. Balance and Sport
  25. 26. Balance and Sport
  26. 27. The Double Decker Bus <ul><li>Each of the diagrams on the right represent a Double Decker bus with passengers inside. </li></ul><ul><li>Draw out and label the one which shows all passengers on </li></ul><ul><li>the lower level </li></ul><ul><li>the upper level </li></ul><ul><li>both levels </li></ul>
  27. 28. Delete a word to complete the sentences <ul><li>If more people sit upstairs on the bus the CoG will rise/fall. This will make the bus more stable/unstable and it can be tilted by a greater/lesser angle </li></ul><ul><li>The bus will fall over when the CoG acts inside/outside of the bus’ base </li></ul><ul><li>A stable object has a low/high CoG and a narrow/wide base </li></ul>
  28. 29. Question Time <ul><li>Page 56 </li></ul><ul><li>Questions 37-39 </li></ul>

×