AS Mechanics Flashcards
define particle
dimensions of the particle are negligible
what are the modelling assumptions for a particle?
mass of the object is concentrated at a single point
spin/rotational force & air resistance are ignored
define rod
all dimensions except 1 are negligible, like a pole or beam
what are the modelling assumptions for a rod?
mass is concentrated along a line
no thickness
rigid (does not bend or buckle)
define lamina
object with area but negligible thickness, like sheet of paper
what are the modelling assumptions for a lamina?
mass is distributed across a flat surface
define uniform body
mass is distributed evenly
what are the modelling assumptions for a uniform body?
the mass of the object is concentrated at a single point at the geometrical centre of the body = the centre of mass
define light object
mass of the object is small compared to other masses, like a string or pulley
what are the modelling assumptions for a light object?
treat object as having 0 mass
tension is the same at both ends of a light string
define inextensible string
a string that does not stretch under load
what are the modelling assumptions for an inextensible string?
acceleration is the same in objects connected by a taut inextensible string
what are the modelling assumptions for a smooth surface?
there is no friction b/w the surface & any object on it
define rough surface
surface that is not smooth
what are the modelling assumptions for a rough surface?
objects in contact with the surface experience a frictional force if they are moving or acted on by a force
define wire
rigid, thin length of metal
what are the modelling assumptions for a wire?
treated as one-dimensional
define smooth & light pulley
all pulleys
what are the modelling assumptions for a smooth & light pulley?
pulley has no mass
tension is the same on either side of the pulley
define bead
particle with hole in it for threading on a wire or string
what are the modelling assumptions for a bead?
bead moves freely along a wire or string
tension is the same on either side of the string
define peg
a support from which a body can be suspended or rested
what are the modelling assumptions for a peg?
no dimensions & fixed
can be rough or smooth - depends on Q
define air resistance
resistance experienced as an object moves through air (opposite direction to motion)