Newton's first law states that every object will remain at rest or
in uniform motion in a straight line unless compelled to change
its state by the action of an external force (aka. inertia).
The third law states that for every action (force)
in nature there is an equal and opposite reaction.
The second law explains how the velocity of an object
changes when it is subjected to an external force.
Formulas
Speed = distance / time
net Force = mass x acceleration
Acceleration = v - u / time
Pressure = force / area
Density = mass / volume
Weight = mass x gravitational acceleration
(Hooke's Law) F = kx
Work Done = force x distance
Forces
SCALAR VS VECTOR
SCALAR quantities have magnitude only. (speed)
VECTOR quantities have magnitude and an associated direction. (velocity)
CONTACT VS NON CONTACT
contact forces - the objects are physically touching
e.g. friction, air resistance or tention
non-contact - the objects are physically separated
e.g. gravitational force, electrostatic force or
magnetic force
RESULTANT FORCES
resultant force = the total effect of all the
different forces acting on an object
WORK DONE AND ENERGY TRANSFER
work is done when a force causes an object to move. the force causes a displacement
GRAVITY
weight is the force acting on an object due to gravity
all matter has a gravitational field that causes attraction. the
field strength is much greater for massive objects
Elasticity
SPRING CONSTANT
stretching - when a spring is stretched, the
force pulling it exceeds the force of the spring
bending - when a shelf bends under the weight of too many books, the downward
force is from the weight of the books, and the shelf is resisting this weight
compressing - when a car goes over a bump in the road, the
force upwards is opposed by the springs in the car's suspension
ELASTIC DEFORMATION
Elastically deformed - stretched object that returns
to it's original length after the force is removed
INELASTIC DEFORMATION
Inelastically deformed - stretched object that does not
return to its original length after the force is removed
Stopping Distance
THINKING DISTANCE
distance travelled before the driver applies the brakes
BRAKING DISTANCE
distance a vehicle travels after the brakes have been applied