27 terms

# As Physics (edexcel) materials

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Terminal velocity
The greatest steady speed a falling object will reach, when the forces acting are balanced
Upthrust
When a body is partially or totally immersed in a fluid, the upthrust is equal to the weight of fluid it displaces
Density
Mass / volume
Streamlined or laminar flow
The fluid does not make any abrupt changes in direction or speed and the adjacent layers do not mix.
Turbulent flow
The fluid does make abrupt changes to direction and speed and there is mixing between layers. Eddies are formed.
Viscous drag
The drag force exerted on an object as it moves through a fluid or the fluid flows past it. It can be calculated using stokes law.
Elastic
Returns to its original shape when load is removed
Plastic
Remains deformed when load is removed
Brittle
Cracks and brakes without plastic deformation
Tough
Does not readily crack, can with stand dynamic loads such as shock and impact
Ductile
Can be deformed plastically under tension; can be pulled into a long thin shape
Malleable
Can be deformed plastically under compression; can be hammered into a sheet
Hard
Stiff
Requires a large force to produce a small deformation
Durable
Smooth
Low friction surface
Hooke's law
Force is proportional to extension
Young's modulus
Stress / Strain
Stress
Force / cross sectional area
Strain
Extension / original length
Elastic energy
Area under force-extension graph and E = 1/2 F x
Tension
A pulling force
Compression
A squashing force
Tensile Strength
Greatest stress before fracturing
Limit of proportionality
Stress is proportional to strain up to this point. / Hooke's law is obeyed up to this point.
Yield Point
Point at which plastic deformation begins/ point at which material shows a larger increase in stress for a smaller increase in strain.
High Tensile Strength
Under go a large force (under tension) before breaking