Wednesday, 4 June 2014

Centre of mass & stability

Equipment

2 litre straight sided plastic drinks bottle with lid
Ruler
Protractor
Water
Wooden board with wooden lolly stick glued on

Method

Place the empty bottle on the wooden board so that the edge of the base buts up against the lolly stick so it does not slide.
Align the centre of the protractor with the edge of the board and slowly raise the opposite side so that the bottle starts to lean.
When the bottle falls read off the angle on the protractor. Repeat this at least twice more.
Add 5cm depth of water to the bottle using the ruler to measure.
Screw the lid on again tightly and repeat the tipping and recording of the topple angle.
Continue to add 5cm dept of water and repeat the tipping until the bottle is full.

Plot a graph of water height vs toppling angle. Why does it have this shape?

Risk assessment

Ensure lid is screwed on tightly when carrying out this experiment. Any spills should be mopped up straight away. As the bottle fills it will become heavier and could hurt feet if it rolls off the table, to reduce the chance of this happening carry out the experiment in the middle of the table and have a second person ready to catch the bottle as it falls.