Modelling assumptions mechanics

Question 1

Particle- meaning

Answer 1

• Dimensions of the object are negligible

Question 2

Particle- assumptions that can be made

Answer 2

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

Question 3

Rod - Meaning

Answer 3

All dimensions except one are negligible

Question 4

Rod- Assumptions that can be made

Answer 4

• mass is concentrated along a line
  -no thickness
  -rigid

Question 5

Lamina- meaning

Answer 5

An object with area but negligible thickness, like a sheet of paper

Question 6

Lamina - assumptions

Answer 6

mass is distributed across a flat surface

Question 7

Uniform body-meaning

Answer 7

mass is spread evenly

Question 8

Uniform body- assumptions

Answer 8

mass is concentrated at the centre of mass

Question 9

Light object- meaning

Answer 9

mass of the object is small compared to the mass of other objects

Question 10

Light object assumptions

Answer 10

-Treated as having zero mass
- Tension is the same on both ends of the light string

Question 11

Inextensible string meaning

Answer 11

The string doesn’t stretch under load

Question 12

Inextensible string assumptions

Answer 12

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

Question 13

Smooth surface assumptions

Answer 13

There is no friction between the surface and any object on it

Question 14

Rough surface assumptions

Answer 14

Objects in contact with the surface experience a frictional force when moving

Question 15

Wire meaning

Answer 15

Rigid thin length of metal

Question 16

Wire assumptions

Answer 16

treated as one dimensional

Question 17

Bead meaning

Answer 17

Particle with a hole in it for threading on a wire or a string

Question 18

Bead assumptions

Answer 18

-Moves freely on a wire or string
- Tension is the same either side of the bead

Question 19

Peg meaning

Answer 19

A support from which a body can be suspended or rested

Question 20

Peg assumptions

Answer 20

• dimensionless and fixed
  -can be rough or smooth

Question 21

Air resistance meaning and assumptions

Answer 21

M- resistance experienced as an object moves through the air
A-Usually modelled as negligible

Question 22

Gravity - assumptions

Answer 22

• assume all objects with mass are attracted towards other
• earths gravity is uniform and acts vertically downwards