Mechanics Flashcards
Assumptions 2
Particle- dimensions are negligible
Mass of the object is concentrated at a single point
rotational forces and air resistance can be ignored
Assumptions 3
rod- all dimensions are negligable
Mass is concentrated along a line
no thickness
Rigid (does not bend or buckle)
Assumptions 1
Lamina object with area but negligible thickness
mass is distributed across a flat surface
Assumptions 1
uniform body- mass is distributed evenly
mass of the object is concentrated at a single point at the geometrical centre of the body- the centre of mass
Assumptions 2
light object- mass of the object is small compared to other masses like a sting or pulley
Treat object as having zero mass
tension the same at both ends of a light string
Assumptions 1
inextensible string- a string that does not stretch under load
acceleration- is the same in objects connected by a taut inextensible string
Assumptions 1
Smooth surface
assume that there is no friction between the surface and any object on it
Assumptions 1
Rough surface
objects in contact with the surface experience a frictional force if they are moving or acted on by a force
Assumptions 1
wire- rigid length of metal
Treated as one dimensional
Assumptions 2
smooth and light pulley- and pulleys you consider will be smooth and light
pulley had no mass
tension is the same on either side of the pulley
Assumptions 2
particle with a hole in it for threading a wire or string
moves feely along a wire or string
tension is the same on either side of the bead
Assumptions 2
Peg- a support which a body can be suspended or rested
dimensionless (unitless) and fixed
can be rough or smooth as specified in question
Assumptions 1
Air resistance
usually modelled as being negligible
Assumptions 3
gravity- force of attraction between all objects
assume that all objects with mass are attracted towards the earth
earths gravity is uniform and acts vertically downwards
g is constant and taken as 9.8 ms-2, unless otherwise stated in the question
