3Turn-2

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

Give pupils whiteboards and have them write down the method for the practical they did the previous lesson - finding the centre of mass using a plumb line. Give them a few minutes and then ask for some of their answers to be fed back to the class.

Main Body of Lesson

Pupils need to be able to talk about this method and it is often worth 4 marks. The best way for them to answer this question is with a bullet pointed list. This helps cut down the amount of waffle they are likely to give.

Next move on to looking at stability. Although it is not explicitly in the spec it is a natural progression from the CoG work and gives it some context. Set up the tipping ramp at the front and ask them to predict which will tip over first: A full glass of wine or an empty glass of wine? Move on and return to it later. Next ask them to think of things which fall over easily and things which are hard to push over. Ask pupils to write down (on whiteboards) features which make objects hard to push over. Link this to stability. You can give some ideas to help them here such as different 3D shapes, F1 car, clamp stand etc. Try to get pupils to identify wide base and low CoG. Come back to the two wine glasses. Tip the board and see which goes first. Ask pupils

After this you can talk about the 3 types of equilibrium (stable, unstable and neutral)again linking all of these to CoG

Plenary

Ask pupils to come up with the most stable position they can think of. Most will try to get low and have a wide base but stay on their feet. Some may lay down flat as this gives them the widest base and the lowest CoG

Homework

Read 56-57, answer qs on pg 57

Additional Information

Resources Required

~Stability demos (now includes the tipping wine glass demo)

Textbook References

pg 56-57

Website References

• None

Safety/Hazards

Try to avoid letting the wine glasses crash into the desk.

Notes

• None