Chapter 2 section 2 physics

Solids have definite shapes that they can ?

Preserve

Which on the atomic scale they are only made out of?

Atoms and molecules

Where do they vibrate and compared to what?

They vibrate around the equilibrium of atoms which the vibrations is really small compared to the distance between atoms

The arrangment of molecules depends onmany factors

1 the shape of the molecule

2 the stress of inneratomic force affecting on the molecule by attraction and temprature

The composition of many solids vary on?

Temprature

Beside that there inner atomic composition changes when putting stress on a rigid body

The properties of an solid depends on?

How the mlecules are arranged and how that arrangement effects the density

How de we get a density of a solid where its particles are spheres?

We can make an estimated cube and get volume of of that and divide mass with it and whoala we get density

All. The diffrent compositions of solids resualts in?

Diffrent thermal electrical mechanical and magnetic

1 rigid bodies a law of motion of newton

Rigid body

When doesnt it change its shape and what does it not count

All solid bodies are not rigid but all rigids are solid example?

And why?

Elasticity

And its three types

If a applications ocurs and the adding of a non zero force on a body resualts in accelerating or deformations

Rigid body its when an object preserves its shape when applied forces are added to it

Solids change shape and liquid and gases dont

For example sugar is a solid but when force is applied to it it breaks appart but for rigid bodies when force is applied to it the particle get closer thabn the repulsive forces sends them back where they should have been

Elasticity its an objects ability to restore its shape after its deformed by a certain applied force

1 tennis ball shows

2 steel doesnt show bc its a rigid body

3 the mass added to a spring when we take it off its biounces up and down until its at its normal equalibirum but when the masses are still on it its distance becomes shortened becomes the equalibrium changes another example of this is throwing a book on a table

One of newtons laws of what states that when a non zero force is added to an object they either accelerate or dform

Laws of mechanics state

What does oscilat emean?

Jump up and down

Tension is teh solids ability to?

Streatch and compress

Tensiom

Its the force that arises in a body while being stretched or compressed

Tension at any point is?

T

Even if the wire is?

Stretched verticale or accelerated ( compressed)

Example?

Streatching 2 parts of a wire by opposite forces beacuse each wire is at its equalibrium teh sumation of force acting on it is zero which its stated from newtons third law of action and reaction

What is newtons third law?

Its action and reaction

Stress

Its the force applied to a unit area of a cross section of a wire

A stress is applied to elongate a wire and its defined as?

Newton over m cubic

Stress can be?

Tensile stress and there are many ways to put force on a object for example when we compresed an object then it can be called comprehiseve stress

Tension is directly proportional to?

Elongation

What can the areas of teh stress determine

If its added perpendiculary to the cross section then its tensile of compresive

If its added to the tangent direction (parallel) then its called shear stress

The shear stress on a block is under tension which is …. To its cross section

Parralel

An elastic spring elongates when tension is added to it when tension is dropped

It restores its shape beacuse of teh elastic property BUT if there is alot of tension the sprign can get damaged and can be permenantly deformed

Roberthook state dthat tension? When?

Tension of a tsring is directly proportional to the elongation of the string

T=k n/m its rigidities contstant measure

In the seventeenth century

How ever for metals its diffrent

It has more factors including the tension

The radius of the wire the length of tehj wire and the material used

We have four examples

First the lengths are diffrent but the amount of force needed for a area cross section of the tension remains the same. That means tension= l -l0/l0

Where l its the elon gatipn pf the wire and l0 its the initial lenth

Teh second pictuyre more energy is needed for the three strings to get far away from each other

The third picture less energy is needed for thiner radiuses

The fourthj picture less energy is needed for the two paralel lines to expand

Strain

Its teh ratio between initial length and elongation

When stress is aplied proportional

amount of strain happens to the certain material as long as the stress doesnt surpase the direct proportionality

The si unit of young modelus?

N/m² its the same as stress beacuse strain is unit less

Pa ==

N/m² = kg/mxs²