Modelling in mechanics Flashcards
(15 cards)
1
Q
Particle
A
- dimensions are negligible
- mass is concentrated at a single point
- air resistance and rotational forces are ignored
2
Q
Rod
A
- all dimensions but one are negligible (eg pole or beam)
- mass is concentrated along the line
- rigid (does not bend)
3
Q
Lamina
A
- has area, but thickness can be ignored (eg: sheet of paper)
- mass distributed across a flat surface
4
Q
Uniform body
A
- mass of the object is concentrated at the centre of the object (centre of mass)
- mass is distributed evenly
5
Q
Light object
A
- mass of object is very small compared to the other masses (eg: string or pulley)
- object treated like it has 0 mass
- tension is the same at both ends of a light string
6
Q
Inextensible string
A
- string doesn’t stretch under load
- acceleration is the same in objects connected by a taut inextensible string
7
Q
Smooth surface
A
- no friction between any object on it and the surface
8
Q
Rough surface
A
- friction between the surface and any object on it if the object is acted upon by a forced
9
Q
Wire
A
- rigid thin length of metal
- treated as 1D
10
Q
Smooth and light pulley
A
- pulley has no mass
- no friction between the pulley and the string
- tension is the same on either side of the string
11
Q
Bead
A
- particle with a hole in it for threading on a wire or string
- moves freely along the wire/string
- tension is the same on either side of the bead
12
Q
Peg
A
- support used to suspend or rest bodies on
- dimensionless
- can be rough or smooth
13
Q
Air resistance
A
- resistance experiences as an object is moving through air
- usually modelled as negligible
- opposes motion
14
Q
Buoyancy
A
Upward force on a body that allows it to float or rise when submerged in a liquid
15
Q
Compression / Thrust
A
Force acting on an object if the object is being pushed along using a light rod
