MECHANICSY1 ch8 modelling assumptions

Question 1

Particle

Answer 1

• mass concentrated at a single point
• air resistance and rotational forces can be ignored

Question 2

Rod

Answer 2

• mass concentrated along a line
• no thickness
• rigid

Question 3

Lamina

Answer 3

• mass distributed along flat surface
• has area but negligible thickness

Question 4

Uniform body

Answer 4

• mass is evenly distributed

Question 5

Light object

Answer 5

• treat as having no mass
• tension is the same at both ends of a light string

Question 6

Inextensible string

Answer 6

• does not stretch under load
• acceleration is same in objects connected by a taut inextensible string

Question 7

Smooth surface

Answer 7

• no friction between surface and object

Question 8

Rough surface

Answer 8

• fictional force occurs between object and surface

Question 9

Wire

Answer 9

• rigid thin length of metal
• treated as one dimensional

Question 10

Smooth and light pulley

Answer 10

• all pulleys
• no mass
• tension is same on either side

Question 11

Bead

Answer 11

• particle with hole in for wire or string
• tension same on either side of bead

Question 12

Air resistance

Answer 12

• resistance experienced as object moves through air

Question 13

Gravity

Answer 13

• force of attraction between all objects
• acceleration due to gravity is 9.8m/s