Modeling In Mechanics

Question 1

Particle

Answer 1

Dimension of the object are negligible

Question 2

Particle model assumptions

Answer 2

-mass of the object is concentrated at a single point
-rotational forces and air resistance can be ignored

Question 3

Rod model

Answer 3

All dimension but one are negligible like a pole or beam

Question 4

Rod model assumptions

Answer 4

-Mass is concentrated along a line
-no thickness
-rigid (doesn’t buckle or bend)

Question 5

Laminate model

Answer 5

Object with area but negligible thickness like a piece of paper

Question 6

Lamina model assumptions

Answer 6

Mass is distributed across a flat surface

Question 7

Uniform body model

Answer 7

Mass is distributed evenly

Question 8

Uniform body model assumptions

Answer 8

-mass of the object is concentrated at a single point at the geometrical centre of the body, centre of mass

Question 9

Light object model

Answer 9

Mass of the object is small compared to other masses like a string or puller

Question 10

Light object model assumptions

Answer 10

-treat object as having 0 mass
-tension the same at both ends of a light string

Question 11

Inextensible string model

Answer 11

A string that doesn’t stretch under load

Question 12

Inextensible string model assumptions

Answer 12

Acceleration is the same in objects connected by a taut Inextensible string

Question 13

Smooth surface model

Answer 13

Self explanatory

Question 14

Smooth surface model assumptions

Answer 14

No friction between the surface and any objects on it

Question 15

Rough surface model

Answer 15

If surface isn’t smooth

Question 16

Rough surface model assumptions

Answer 16

Objects in constant with surface experience as frictional force if they are moving or are acted on by a force

Question 17

Wire model

Answer 17

Rigid thin length of metal

Question 18

Wire model assumptions

Answer 18

Treated as one dimensional

Question 19

Smooth and light pulley model

Answer 19

All puller you consider will be smooth and light

Question 20

Small and light pulley model assumptions

Answer 20

-pulley has no mass
- tension is the same on either side of the pulley

Question 21

Bead model

Answer 21

Particle with a hole init for threading on wire or string

Question 22

Bead model assumptions

Answer 22

Moves freely along wire or string
-tensions is the same on both side of the bead

Question 23

Peg model

Answer 23

Support from which a body can be suspended or rested

Question 24

Peg model assumptions

Answer 24

-dimensionless and fixed
-can be smooth or rough should be specified in Q

Question 25

Air resistance

Answer 25

Resistance experienced as an object moves through air

Question 26

Air resistance assumptions

Answer 26

Usually modelled as being negligible

Question 27

Gravity

Answer 27

Force of attraction between all objects accleration due to gravity is denoted eg g=9.8 ms ^-2

Question 28

Gravity assumptions

Answer 28

-All objects with mass are attracted to the earth
-earths gravity is uniform and acts vertically downwards