Definitions !Definitions !

Forces and MotionForces and Motion

Acceleration !Acceleration !Acceleration is the rate of change Acceleration is the rate of change

of velocity, with respect to time.of velocity, with respect to time.

Velocity !Velocity !Velocity is the rate of change of Velocity is the rate of change of

displacement, with respect to time.displacement, with respect to time.

Vectors !Vectors !Vectors, unlike scalars, have both Vectors, unlike scalars, have both

a magnitude and a direction.a magnitude and a direction.

Scalars !Scalars !Scalar quantities have only a Scalar quantities have only a

magnitude.magnitude.

Power !Power !Power is the work done per unit of time.Power is the work done per unit of time.

Power (W) = Power (W) = work donework done timetime

Power (W) = Force x SpeedPower (W) = Force x Speed

Weight !Weight !The weight of a body is the force The weight of a body is the force

of gravity acting on a body, it is of gravity acting on a body, it is measured in Newton’s (N).measured in Newton’s (N).

Density !Density !Density can be defined simply as Density can be defined simply as

“mass per unit volume”.“mass per unit volume”.Density (Kg/mDensity (Kg/m33) = ) = MassMass

VolumeVolume

Pressure !Pressure !The force being applied per unit area.The force being applied per unit area.

Pressure (Pa) = Pressure (Pa) = ForceForce

AreaArea

Strain !Strain !The strain on an object is the The strain on an object is the extention against the original extention against the original

length. length.

Stress !Stress !The force being applied per unit area.The force being applied per unit area.

Stress (Pa) = Stress (Pa) = ForceForce

AreaArea

Young’s ModulusYoung’s ModulusYoung’s Modulus, measured in Young’s Modulus, measured in

“Pa” (Pascal) is simply:“Pa” (Pascal) is simply:

Young’s Modulus = Young’s Modulus = StressStress

StrainStrainMoments !Moments !

A Moment is the product of force A Moment is the product of force and the perpendicular distance and the perpendicular distance

from a pivot.from a pivot.

Speed !Speed !Speed is the rate of change of Speed is the rate of change of

distance.distance.

Speed = Speed = DistanceDistance

TimeTime

Watt !Watt !One watt is one joule of energy One watt is one joule of energy

transferred per second.transferred per second.

The Four Equations of The Four Equations of Motion !Motion !v = u + atv = u + at

v = uv = u²² + 2as + 2as

S = S = (u+v)(u+v)tt

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S = ut + S = ut + ½ at²½ at²

Kinetic Energy !Kinetic Energy !Kinetic Energy = ½Kinetic Energy = ½MvMv² (J)² (J)

Potential Energy !Potential Energy !Potential energy = Mgh (J)Potential energy = Mgh (J)

Work Done !Work Done !Work Done = Force X Distance Moved (J)Work Done = Force X Distance Moved (J)

Newton’s 3 Laws of Newton’s 3 Laws of MotionMotion

Law Of InertiaLaw Of Inertia

Every object in a state of uniform motion tends to Every object in a state of uniform motion tends to remain in that state of motion unless an external remain in that state of motion unless an external force is applied to it.force is applied to it.

Force = Mass x AccelerationForce = Mass x Acceleration

The relationship between an object's mass (The relationship between an object's mass (m)m), its , its acceleration (a), and the applied force (f) is “acceleration (a), and the applied force (f) is “F = F = ma”ma”. Acceleration and force are vectors. In this . Acceleration and force are vectors. In this law the direction of the force vector is the same law the direction of the force vector is the same as the direction of the acceleration vector.as the direction of the acceleration vector.

For every action, there is an equal reactionFor every action, there is an equal reaction

(e.g. Stepping off a boat onto the shore/dock causes (e.g. Stepping off a boat onto the shore/dock causes the boat to drift back in the opposite direction. the boat to drift back in the opposite direction. Thus leaving the person in the water, IF they are Thus leaving the person in the water, IF they are not careful!)not careful!)