Modelling Assumptions Flashcards
How many modelling assumptions are there
14
What is assumed if something is a particle (4)
-mass concentrated at a single point
-air resistance can be ignored
-rotational forces can be ignored
-dimensions of object ignored
What is assumed if something is a rod
(3)
-no thickness
-rigid
-mass concentrated along a line
What is assumed if something is a lamina
(1)
mass is distributed across a flat surface
what is assumed if something is a uniform body (1)
mass of object is concentrated at a single point in the geometric centre
what is assumed if something is a light object (2)
-treat object as having 0 mass
-tension the same at both ends of a light string
what is assumed of something is an inextensible string (1)
acceleration is the same in objects connected by a taut inextensible string
what is assumed on a smooth surface (1)
no friction between surface and any object on it
what is assumed on a rough surface (1)
objects in contact with the surface experience a frictional force moving or acted on by a force
what is assumed if something is a wire (1)
treated as 1 dimensional
what is assumed if something is a smooth and light pulley (2)
-pulley has no mass
-tension the same either side of the pulley
what is assumed if something is a bead (2)
-moves freely along wire or string
-tension the same either side
what is assumed if something is a peg (2)
-dimensionless and fixed
-can be rough or smooth
what is assumed with air resistance (1)
usually modelled as being negligible
what is assumed with gravity (3)
-all massed objects are attracted towards earth
-earth’s gravity is uniform and acts vertically down
-g is taken unless specified as 9.8ms-2
