Modeling In Mechanics Flashcards
Particle
Dimension of the object are negligible
Particle model assumptions
-mass of the object is concentrated at a single point
-rotational forces and air resistance can be ignored
Rod model
All dimension but one are negligible like a pole or beam
Rod model assumptions
-Mass is concentrated along a line
-no thickness
-rigid (doesn’t buckle or bend)
Laminate model
Object with area but negligible thickness like a piece of paper
Lamina model assumptions
Mass is distributed across a flat surface
Uniform body model
Mass is distributed evenly
Uniform body model assumptions
-mass of the object is concentrated at a single point at the geometrical centre of the body, centre of mass
Light object model
Mass of the object is small compared to other masses like a string or puller
Light object model assumptions
-treat object as having 0 mass
-tension the same at both ends of a light string
Inextensible string model
A string that doesn’t stretch under load
Inextensible string model assumptions
Acceleration is the same in objects connected by a taut Inextensible string
Smooth surface model
Self explanatory
Smooth surface model assumptions
No friction between the surface and any objects on it
Rough surface model
If surface isn’t smooth
Rough surface model assumptions
Objects in constant with surface experience as frictional force if they are moving or are acted on by a force
Wire model
Rigid thin length of metal
Wire model assumptions
Treated as one dimensional
Smooth and light pulley model
All puller you consider will be smooth and light
Small and light pulley model assumptions
-pulley has no mass
- tension is the same on either side of the pulley
Bead model
Particle with a hole init for threading on wire or string
Bead model assumptions
Moves freely along wire or string
-tensions is the same on both side of the bead
Peg model
Support from which a body can be suspended or rested
Peg model assumptions
-dimensionless and fixed
-can be smooth or rough should be specified in Q
Air resistance
Resistance experienced as an object moves through air
Air resistance assumptions
Usually modelled as being negligible
Gravity
Force of attraction between all objects accleration due to gravity is denoted eg g=9.8 ms ^-2
Gravity assumptions
-All objects with mass are attracted to the earth
-earths gravity is uniform and acts vertically downwards
