Maths Applied - Modelling Assumptions

Question 1

Particle

Answer 1

• Dimensions of the object are negligible
• Mass is concentrated at a single point
• Air resistance and rotational forces can be ignored

Question 2

Rod

Answer 2

• An object with 1 dimension (length and width), such as a pole or a beam
• Mass is distributed along a straight line
• Rigid (does not bend or buckle)

Question 3

Lamina

Answer 3

• Object with 2 dimensions, such as a sheet of metal
• Its mass is evenly distributed across a flat surface

Question 4

Uniform body

Answer 4

• Mass is evenly distributed
• Mass is concentrated at the geometrical centre of the body (centre of mass)

Question 5

Light String

Answer 5

• Mass is very small (usually regarded as 0), such as a string or pulley.
• Tension is the same at both ends of a light string

Question 6

Inextensible string

Answer 6

• Does not stretch under a load
• Acceleration is constant in objects connected by a taught inextensible string

Question 7

Smooth

Answer 7

Assumes there is no friction between this surface and an object

Question 8

Rough

Answer 8

This takes into account friction on surfaces

Question 9

Wire

Answer 9

A rigid, thin length of metal, treated as one dimensional, either smooth or rough

Question 10

Air resistance

Answer 10

The friction an object experiences as it moves through space (in air)

Question 11

Gravity

Answer 11

• The force of attraction to the Earth, measured at 9.8m/s^2.
• It is uniform and acts vertically downwards