# Physics AS Mechanics

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• Physics AS Mechanics
• Motion
• Motion graphs
• average speed=distance/time
• Displacement in a specific direction
• Velocity/time graph
• Area= displacement
• Vectors
• Represented by arrows
• Trig to work out resultant force
• If only have resultant force find compnents
• Scalars
• Vector Quatitys
• Magnitude and direction
• Displacement
• Acceleration
• Force
• Velocity
• Momentum
• Scalar Quatitys
• Magnitude only
• Tempurature
• Density
• Distance
• Pressure
• Speed
• Work and Energy
• Efficiency
• efficiency=useful energy/total input energy
• x 100 to make it percentage efficiency
• Sankey  diagrams
• shows out put of an appliance. Useful and not useful
• Conservation of energy
• Energy cannot be created or destroyed
• Only transformed
• Sankey  diagrams
• shows out put of an appliance. Useful and not useful
• Forms of energy
• Chemical,Electrical, Gravitational potential, Nuclear, Sound, Knetic
• Only transformed
• Gravitational potential energy
• The energy a body has by virtue of its position in a gravitational field
• Ep=mgh
• Knetic energy
• The energy a body has by virtue of its motion
• Ek=1/2 mv^2
• Power
• Watt(w)
• 1 watt is the power when i joule is done in 1 second
• 1W=1Js^-1
• Power=work done/time taken
• Power= transferred / time
• Watt(w)
• 1 watt is the power when i joule is done in 1 second
• 1W=1Js^-1
• W=fx in direction of the force
• Materials
• Elastic
• material stretches and follows hookes
• A material follows hookes law when the extention producedis proportional to the force providing it
• only when the elastic limit has not been exceeded
• When elastic limit has been reached object is permanently deformed
• Young Moduls= stress/ strain
• Stress=force/ cross sectional area
• Strain= Extension/ Length
• Work Done
• W=fxcos0 is the force is at an angle to the direction of the force
• W=fx in direction of the force
• 1 Joule= 1 Newton metre, when a force of 1N moves an object over a distance of 1M
• Forces
• Resultant forces
• F=ma
• Resultant force= massx acceleration
• The newton= force that causes 1KG to accelerate at 1ms^-1
• Does not work for high speeds as mass increases
• Balanced forces
• Terminal velocity
• Drag= weight and acting forces
• Opposes motion
• Weight=mg
• Centre of gravity
• Where all the WEIGHT is considered to act as 1 force
• Find COG hang from 1 point, draw along plumb line, do with 2 more different points
• Turning forces
• Couple
• 2 equal and opposite forces acting the opposite direction producing rotation
• Torque describes the turning effect of the couple
• Torque= force x perpendicular distance
• Pressure
• Pressure= force/ area
• 1Pa= 1N spread evenly over 1m^2
• Force per unit area
• Density
• Mass per unit volume
• Kgm^-3
• Density= mass/ volume
• Makes things float or sink
• Car Safety
• Crumple zones increase time of deceleration
• seat belts and airs bags do the same
• Thinking distance= speedx thinking time
• Breaking distance UVAST
• Stopping distance= Breaking + Thinking