3Turn-1

Outcomes

• Pupils can find the centre of gravity for a lamina using a pin and plumbline.
• Pupils can label the centre of gravity for a range of objects and can appreciate that it may not be located on the object itself.

Specification References

1.16 recall that the weight of a body acts through its centre of gravity

Starter

Demonstrate some of the balaning demos we have (such as the balancing cutlery or the tilting can) Try to get the pupils to think about what's going on. You could also balance a retort stand on the edge of a desk, again try to get the pupils to think what's going on.

Main Body of Lesson

• Introduce the idea of centre of gravity. Centre of Gravity Powerpoint Use several regular shaped objects and discuss where the weight would act if 'all' the weight vectors for every part of the object had to be replaced by one weight vector. Balancing the object on your finger on different sides could easily lead to the correct answer. Lead into irregular object and have the pupils estimate where the c. of g. would be, one object, such as a boom-a-rang with a c. of g. which is not located on the object would also be beneficial.
• Have the pupils cut a lamina out of the card and use the pin and plumbob method to find its centre of gravity.

Plenary

Demonstrate how to find the centre of mass for a clamp stand. Ask pupils to predict where this will be and then show them. Could place a bit of tape on the long part of the stand and have a few pupils note down their answer and then check to see who is the closest.

Homework

Read 56-57, answer qs on pg 57

Additional Information

Resources Required

• Starter - All the awesome balancing demos (match stick on forks, tilting can of doom etc.)
• Centre of gravity- A few regular objects and irregular objects to help discuss centre of gravity including a boom-a-rang.
• Class set of card, scissors, retort stand, cork and pin, sting and plasticine.

Textbook References

pg 56-57

Website References

• None

Notes

• None