38
9L PRESSURE AND MOMENTS
9L PRESSURE AND MOMENTS
PRESSURE
What is the equation for calculating pressure?
Name 2 ways that pressure can be increased.
What are the units of pressure?
CALCULATING PRESSURE
Pressure (N/cm2) = Force (N)
Area (cm2)
AIM: TO INVESTIGATE HOW THE PRESSURE I EXERT ON THE GROUND CHANGES.
Body part/shoe
Area (cm2) Force (N) Pressure (N/cm2)
1 foot
2 feet
1 hand
2 hands
CALCULATING PRESSURE
Pressure (N/cm2) = Force (N) b
Area (cm2)
e.g. Pressure = force ÷ area
= 700 ÷ 20
= 35 N/cm2
ALWAYS1. Formula2. Add numbers3. Answer4. Units
WATER PRESSURE
What is water pressure?
Which direction does it act in?
How does it change with depth?
SCUBA DIVING EXPERIMENTS
http://youtu.be/PavY_JmYyTs
http://youtu.be/HlZXDcSR-Z4
http://youtu.be/t8wFIMbMJvs
Polystyrene cup
http://www.sciencedump.com/content/what-happens-coffee-cup-2300-meters-depth-ocean
Mythbusters
http://youtu.be/YU2PSHeFSlA
AIR PRESSURE
What is air pressure?
How does it change with altitude?
How can you increase air pressure?
DEMOS
http://www.youtube.com/watch?v=_xB7q6bJ8k8
http://www.youtube.com/watch?v=QeAp3CuGjk8
MOMENTS
What is a moment?
Complete this formula:
Moment ( ) =
What unit is a moment measured in?
WHY DID THIS HAPPEN?
BALANCINGLeft Right
Distance from fulcrum (m)
Mass (g) Weight (N)
Moment (Nm)
Distance from fulcrum (m)
Mass (g) Weight (N)
Moment (Nm)
CONVERTING MASS TO WEIGHT
Mass (kg) = mass (g) ÷ 1000
Weight (N) = mass (kg) ÷ 10
CALCULATING THE MOMENT
Moment (Nm) = Force (N) x distance (m)ALWAYS1. Formula2. Add numbers3. Answer4. Units
LEVERS
What is a lever?
Name 5 examples of where we use levers.
LETS LOOK AT A BIKE AND SOME TOOLS
PLENARY
Find the lever and fulcrum
Capsizing
http://youtu.be/S-FlN97Y3ok
World speed sailing record
http://youtu.be/qzkulFGa4Mc
Moth boat
http://youtu.be/1SN1gSkqvy0
L´Hydroptere
http://youtu.be/MdUyLxVa6xQ
Sailrocket 2 2012 record (125km/h)
http://youtu.be/pipGWQmerEQ
Windsurf speed record
http://youtu.be/t15LZ1Er-a8
