# Physics Paper 2 - Forces - AQA

• Forces - Paper 2 GCSE Physics (AQA)
• Contact and Non-Contact Forces
• Vectors have Magnitude and Direction
• A Vector is something like: Force, Velocity, Displacement, acceleration, momentum etc...
• Scalar have Magnitude but no Direction
• Contact and Non-Contact Forces are pretty self explanatory
• Something physical such as Friction, Air resistance, tension etc are all Contact
• Something non-physical or not touching such as magnetism, gravity, electrostatic forces. Are all Non-Contact
• Weight, Mass and Gravity
• Gravity attracts all masses. This gives everything a weight.Untitled
• Weight =
• Mass x
• Gravitational Field Strength
• Weight is measured in Newtons
• Mass is measured in Kilograms
• GFS is measured in N/Kg
• Mass is the amount of 'stuff' something has
• Resultant Force and Work Done.
• Free Body Diagrams show all the forces acting on an object
• For example, a skydiver will have his weight pulling him down and air resistance acting in the opposite direction
• A resultant force is the Overall Force on a Point or Object
• When a force moves an object through  a distance, ENERGY IS TRANSFERRED and WORK IS DONE
• Elasticity and Springs
• F=KE
• Force(N) = constant(N/m) x extension (m)
• 1/2 KE^2
• 0.5 x Constant x Extension (SQUARED)
• An object is inelastically de-formed if it does not return to its original shape
• Moments and Newton's Laws
• M = FD
• Moment (Nm) = Force (N) x Distance(m)
• Levers make it easier for us to do work
• Levers increase the distance from the pivot at which the force is applied
• Gears however transmit rotational Effects
• The gears have teeth which interlock and turn eachother
• Gears however transmit rotational Effects
• Newton's Laws (MEMORISE)
• NEWTON'S FIRST LAW
• If the force on an object is zero than the object will remain at the same velocity
• NEWTON'S SECOND LAW
• F = ma
• Force(N) = Mass(Kg) x acceleration(m/s^2)
• NEWTON'S THIRD LAW
• Every action has an equal and opposite reaction
• Pressure and Density
• P = F/A
• Pressure(Pascal's) = Force(N) / Area(m^2)
• D = M/V
• Density is the 'compactness' of a substance
• Distance, Speed and Velocity
• a= change in v/t
• Acceleration = Change in Velocity / Time
• v^2 - u^2 = 2as
• You can show a vehicles journey on a distance-time graph where positive gradient is acceleration
• Terminal Velocity is the maximum velocity an object can face when falling from a certain height
• It occurs when an objects weight and air resistance are equal
• P=mv
• Momentum = mass x velocity
• F= m(change)v / (CHANGE) t

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