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Energy

-it is the ability to do work-the human body convert chemical energy(taken from food or

oxygen) into energy of movement(when we walk or run).Unit=JOUL

-Energy is of many forms and can be transfer from one form to another such as :

.Electrical , mechanical ,heat ,light ,atomic And sound energy.

 Law of Conservation of Energy:

-energy can be stored, but it is not possible to create or destroy.Matter:

-Matter is the material (atoms and molecules) that constructs things on the Earth and in the Universe, it has mass and volume.-

#ENERGY &MATTER#

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1.SOLIDS:These are the substances,which have definite Volume and definite shape.The molecules are

held together by strong forces .2.LIQUIDS: These are the substances,which don’t

have definit shape.The molecules are held together by week forces.

3.GASES: : These are the substances,where the molecules move randomly and there is space between them.

-The atoms or molecules have different structures in solids, liquid and gases, leading to different properties.

-There are 3 fundamental states of matter:

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-Same as energy, it can be stored, but it is not possible to create or destroy.

- NB: Physical properties remain the same as the material is reduced in size.

-Physical Properties of Matter:1 -Form – flexible, stiff, straight, curved.

2- Color – eight basic colors.3 -Shape –circle, triangle, square.

4 -Texture – rough, smooth, hard, soft.5 -Size and weight –big, little, heavy, thin.

6 -Position – over, under, in, out.7 -Speed – fast, slow.

Law of Conservation of Matter:

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 Smallest piece of an element is called an atom-.

Smallest piece of a compound is called a molecule.-

-molecules are made of atoms.. all molecules of a compound are identical-

- each molecule has the same number and type of atoms.

Atoms & Molecules

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composed of elements in fixed percentages.-water is 89% O & 11% H-.billions of known compounds-.

-organic or inorganic.-same elements can form more than one

different compound.

Compounds:

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 -we can convert energy to matter and vice

versa.(Einstein equation )E=mc²

E=energy(ev)M=the mass of the matter(g)C=speed of light:3×10⁸ m\s

*if we have photon with 9.11×10³¹ kg ,what is the possible energy can be created from this photon?

The relationship between energy and matter

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1-British imperial system:-evolved over hundreds of years.

was common use in UK until recently.-Include foot(length),the pound(mass),and the second(time).

2-metric system :-this is a system for which napoleon was partly responsible.

-include the centimeter(length),the gram(mass),and the second(time). Therefore its called c.g.s system.

 

3 -international system of units:-its referred as SI.

-include meter(length),kilogram(mass),and the second(time).-this system is now used throughout the world.

 

Systems of units There are a number of such systems have evolved like : british imperial system, metric system and international system of units.

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symbol unit quantity

m Meter Length

kg kilogram Mass

SI unite

s Second Time

A Ampere Electric current

K Kelvin Temperature

Mol Mole Amount of substancemole

cd candela Amount of substancemole

time mass length system

second pound foot British imperial system

second gram centimeter metric system

second kilogram meter international system of units

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Abbreviation Amount Powers name

(n) 10-9 nano(µ) 10-6 micro

(m) 10-3 milli

(k) 103 kilo

(M) 106 mega

(G) 109 giga

 *Different between British

imperial system, metric system and international system of units.-Powers of 10(prefixes)

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We will consider five of most important quantities: mass,force,work,energy and power.

 -mass

-Matter, the material of which everything is made, can be quantified in a number of ways.

-SI unite of matter is mole.-one mole of matter contains 6×10²³elementary

particles.(Avogadro`s number).-the kilogram is the SI unit of mass.

-Physical quantities:

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Which move or tend to move a stationary body.--There are many kinds of forces: electrical forces, magnetic

forces, mechanical forces,etc,. F= ma

F=forceM=mass (kg)

a=acceleration ( ms⁻²),who did we get it?? 

a=change in velocity ⁄time elapsed = m/s/s=ms⁻² 

-so the SI unite of force is kg ms⁻² -it also called newton (N)

*A child pushes a 40 kg sled across a frozen pound, what is the force if the sled acceleration at 0.5 ms⁻²?

-force:

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On the earth`s surface, when a body is released it fall downward, accelerating at a rate of 9.81 ms⁻².this value of acceleration is often called (g),the acceleration due to gravity.

 -The gravitational force acting on a body(known as weight) is the

agency which causes it to accelerate downwards, in this case the force is the weight of the body(W),the mass is m , and (g)is the acceleration due to gravity . thus 

W=mg

*if we have a ball with 8 kg mass. what its weight in newtons?

-Gravitational force:

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-work is product of the magnitude of the force and the distance moved. Suppose a patient has collapsed on the floor and we try to lift on the stretcher trolley. if we succeed in lifting him up we have done work(we have applied a force, the lift, and moved the patient through a certain distance upward in the direction of the force)Work = force × distance moved-

= newtons × meter-SI unit is newtons × meter or joule

-in some cases we use the body weight instead of the force because the minimum force required is equal to the weight of the body.

-work:

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*suppose 50-kg patient seated in a wheelchair has to be lifted onto an examination couch which is 0.2m higher than the wheelchair. How much work must be done in order to raise the patient?

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 -it is the ability to do work.

-SI joule same as the unite of work.-there are 2 type of energy: potential energy and

kinetic energy.

-potential energy:-This is the energy stored in a body due to its position.

-it is relative quantity, it has no absolute value.-PE = f × d × h

Potential energy=force×distance×height or( work×height. because work= force×distance)

-energy

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-This is the energy possessed by a body because of its movement.

-KE= ½mv² M=massV=velocity 

-power-net amount of work done

-power= work done/time taken.-Si unit is joule per second or watt(W)

 

 

*if the work done in lifting a patient is 50j,how much power would be required to achieve this lift in 2 second?

 

-kinetic energy:

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.It is the distance moved in a unit time.V=distance/timeUnit=meter/sec

-Velocity