9L Pressure and Moments

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Pressure and Moments : 

20/04/2009 Pressure and Moments W Richards Worthing High School

Pressure – some basic ideas : 

20/04/2009 Pressure – some basic ideas Describe and draw experiments for each of the following ideas: Pressure increases with depth Pressure is the same in all directions at a certain depth

Pressure : 

20/04/2009 Pressure Explain how the following work: A sharp knife is easier to use then a blunt knife A drawing pin A woman with stilettos on might damage a floor more than an elephant would

Pressure : 

20/04/2009 Pressure Pressure depends on two things: How much force is applied, and How big (or small) the area on which this force is applied is. Pressure can be calculated using the equation:

Some pressure questions : 

20/04/2009 Some pressure questions Calculate the pressure exerted by a 1000N elephant when standing on the floor if his feet have a total area of 1m2. A brick is rested on a surface. The brick has an area of 20cm2. Its weight is 10N. Calculate the pressure. A woman exerts a pressure of 100N/cm2 when standing on the floor. If her weight is 500N what is the area of the floor she is standing on? (Hard!) The pressure due to the atmosphere is 100,000N/m2. If 10 Newtons are equivalent to 1kg how much mass is pressing down on every square centimetre of our body?

Some examples of pressure : 

20/04/2009 Some examples of pressure

Gas Pressure : 

20/04/2009 Gas Pressure

Hydraulic systems : 

20/04/2009 Hydraulic systems

Hydraulic systems : 

20/04/2009 Hydraulic systems

Levers : 

20/04/2009 Levers

3 types of lever : 

20/04/2009 3 types of lever Load is on other side of pivot (e.g. seesaw) Load is “outside” the effort, (e.g. biceps) Load is “inside” the effort (e.g. wheelbarrow)

Moments : 

20/04/2009 Moments A moment is a “turning force”, e.g. trying to open or close a door or using a spanner. The size of the moment is given by: Moment (in Nm) = force (in N) x distance from pivot (in m) Calculate the following turning moments: 100 Newtons 5 metres 200 Newtons 2 metres

Balancing moments : 

20/04/2009 Balancing moments The anti-clockwise moment is bigger so the seesaw will turn anti-clockwise

Balanced or unbalanced? : 

20/04/2009 Balanced or unbalanced?

Stability : 

20/04/2009 Stability

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