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Flashcards in Mechanics Deck (20)
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1

What are some modelling assumptions of a particle?

• Mass of object is concentrated at a single point
• Rotational forces and air resistance can be ignored

2

What are some modelling assumptions of a rod?

• Mass is concentrated along line
• No thickness
• Rigid

3

What is a lamina?

Object with area but negligible thickness, like a sheet of paper.

4

What are some modelling assumptions of a lamina?

• Mass is distributed across a flat surface

5

What are some modelling assumptions of a uniform body?

• Mass of object is concentrated at a single point at the geometrical centre of the body (centre of mass)

6

What are some modelling assumptions of a light object?

• Treated as having 0 mass
• Tension the same at both ends of a light string

7

What are some modelling assumptions of an inextensible string?

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

8

What are some modelling assumptions of a smooth surface?

• No friction between the surface and any objects on it

9

What are some modelling assumptions of a rough surface?

• Objects in contact with the surface experience a frictional force if they are moving ot are acted on by a force

10

What are some modelling assumptions of a wire?

• Treated as one dimensional

11

What are some modelling assumptions of a smooth and light pulley?

• Pulley has no mass
• Tension is the same on either side of the pulley

12

What is a bead?

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

13

What are some modelling assumptions of a bead?

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

14

What is a peg?

A support from which a body can be suspended or rested.

15

What are some modelling assumptions of a peg?

• Dimensionless and fixed
• Can be rough or smooth as specified in the question

16

What are some modelling assumptions of air resistance?

Usually modelled as being negligible.

17

What are some modelling assumptions of gravity?

• Assume all objects are attracted towards the Earth
• Earth's gravity is uniform and acts vertically downwards
• g is constant and is taken as 9.8m/s^2 unless otherwise stated

18

What is the normal reaction?

The force which acts perpendicular to a surface when an object is in contact with the surface.

19

What is thrust or compression in a rod?

The force acting on the object when it is being pushed along by a light rod.

20

What is buoyancy?

The upward force on a body that allows it to float or rise when submerged in liquid.