1
Q
Particle
A
- mass of object concentrated at one point
- rotational forces and air resistance can be ignored
2
Q
Rod
A
- mass concentrated along a line
- no thickness
- rigid
3
Q
Lamina
A
- mass distributed across a flat surface
4
Q
Uniform body
A
- mass of object is concentrated at single point at the centre of the body (centre of mass)
5
Q
Light object
A
- treat object as having zero mass
- tension same at both ends of light string
6
Q
Inextensible string
A
- acceleration is the same in objects connected by taut inextensible string
7
Q
Smooth surface
A
assume there is no friction
8
Q
Rough surface
A
- objects in contact with surface experience friction if they are moving or are acted on by a force
9
Q
Wire
A
- treated as one dimensional
10
Q
Smooth and light pulley
A
- pulley has no mass
- tension is same on either side of the pulley
11
Q
Bead
A
- moves freely along a wire or string
- tension is the same on either side of the bead
12
Q
Peg
A
- dimensionless and fixed
- can be rough or smooth as specified in question
13
Q
Air resistance
A
- usually modelled as being negligible
14
Q
Gravity
A
- assume all objects with mass are attracted to Earth
- Earth’s gravity is uniform and acts vertically downwards
- g is constant and is taken as 9.8ms^-2
