# physics as-level summary notes from the mark schemes

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• Created by: nxrx10
• Created on: 28-01-20 15:56

Note that there are not many formulas in my notes, u need to know them.

Uncertainties

• Systematic error: Zero error / wrongly calibrated scale

• Random error: Reading scales from different angles / wrongly interpolating between scale readings

• Systematic error effect: reading larger/smaller than the reading by constant amount

• Accuracy: how close/closeness of the value to the true value

• Precision: range of the values/measurements / size of the smallest division on the measuring instrument

Force & Motion

• Force: rate of change of momentum

• Equilibrium: Resultant Force = 0 / Resultant Torque = 0 / constant velocity

• Displacement: Distance travelled in a specified direction

• Velocity: change of displacement per unit time

• Mass: Property that resists change in motion

• Direction of acceleration: Resultant force acts [direction]

• N’s 2nd law: Resultant Force is proportional to the rate of change of momentum

• Elastic Collision: Energy + KE + Momentum conserved / vapp = vsep (relative v before = (-) relative v after collision)

• Inelastic Collision: Energy + Momentum conserved, KE not conserved / KE converted into sound/heat / particles stick together after collision

• Elastic Collision: total KE before collision = total KE after collision / relative speed of approach = relative speed of separation

• Momentum: Average Force = Rate of change of momentum - Weight

• suvat works in every motion w/ constant acceleration

• Centre of gravity: point where all weight acts on

• Moment: Parallel => no moment about any points

• Moment: Resultant Force at 1 point = Fsinθ + Fcosθ

• Couple: pair of Forces that only produces rotation / equal magnitude / parallel but opposite directions / separated by diameter d

• Torque: 1 of the Forces ⨉ Perpendicular distance between forces

• Projectile: distance = curve path / displacement: horizontal or vertical distance

• Air Resistance: acts in opposite direction of velocity

• N’s 3rd law: reaction force acts from the ground/earth

• N’s 3rd law: Collision: 2 objects have the same time contact

• Graph: +ive to -ive velocity => direction is reversed

Pressure & Density

• Weight = Upthrust + Viscous drag

• Upthrust: Pressure changes with depth => Pressure (Force) acting from the bottom > Pressure (Force) from the top

• Viscous Force: magnitude increases with speed

• Work Done < GPE cos Work Done by Upthrust

• Upthrust = Pressure difference ⨉ Area

Materials

• Deformation of solid: Tensile = stretch / Compressive = squashed

• Obeys Hooke’s law: straight line goes through the origin

• Elastic deformation: Spring returns to its original length as load is removed

• Plastic deformation: Spring undergoes permanent stretch as load is removed

• Elastic region: before elastic/proportionality limit point

• Plastic region: after elastic limit point

• Ultimate strain: Breaking point

Energy

• Conservation of mechanical energy = KE + GPE

• Work done = Magnitude of F × distance moved in the direction of the force

• Work done ≠ KE : loss in Potential energy

• EPE = ½ Fx or  ½ kx²

• GPE: energy of mass due to its position in a gravitational field

• KE: energy of mass due to its motion/velocity