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All things u need to know about physics p3 &p1

silver_moon

silver_moon

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The Chill Master said:
PHYSICS notes


o General physics

• The density of an object only changes when the substance is heated or cooled.
• An object sinks if its density is more than the liquid on which it is placed on, but floats if less dense.
• When there is no air resistance the acceleration of any object is constant (constant= 10m/s)
• Easier to lift an object on the moon because gravity is less on the moon.
• Resultant Force.
• Gravitational, electrostatic and magnetic forces can be applied from a distance, other than that you have to be in contact with the object to apply a force.
• A force applied on an object can cause a change in speed, direction and shape.
• Acceleration, velocity etc. is a vector quantity.
• When an object moves in a circle it is accelerating and at constant speed at the same time; because the direction is changing but the speed is constant.
• Centripetal force is caused by tension in the string (ball on a string), gravity (satellite in space), friction between the tires and the road (a car on the road).
• For an object to be in equilibrium state the resultant force has to be equal or zero (forces up = forces down) and the resultant moment has to equal zero (clockwise moment = anticlockwise moment).
• For the stability of an object it has to have a wide base and a low center of mass.
• To find the center of mass draw two points A and B, hang the object from each hole so that it can swing freely. Tie a weight to each point then draw the vertical line, the center of gravity is where the lines intersect.
• When a car is going up a hill K.E. = Same, G.P.E = Increases, Chemical Energy (petrol) = Decreases and the total energy stays the same as energy is not lost, created or destroyed.
• Internal energy = Thermal energy.
• Fission = Process called when large molecules break down into small. Example: power station of uranium.

• Fusion = Process called when small molecules builds into large molecule. The fusion process produces more energy than fission. Example: Sun.
• The mass lost is converted into heat energy.
• In barometers the space at the top is a vacuum, because air would prevent the mercury from rising.
• The width of the barometer does not affect the height of mercury.
• Water manometers are more accurate to measure gas pressure.
• To get the total pressure, remember to add the atmospheric pressure.
• The gas pressure can be converted from mm of Hg to Pa by using P = density*gravity*height, but remember to use the total pressure.

• Pressure= force/area

• The more the area, the more the force & the less the area the, the less the force.







Thermal Physics
• The pressure is the same on all the walls of the containers as the molecules move in a random motion.

• Temperature is proportional to K.E. + Molecules hit the walls harder and more often.

• Brownian motion: The tiny, fast-moving air molecules, which are in a constant random motion, are hitting the larger smoke particles from all directions.

• Evaporation: It is the vaporization of liquid, when the fast moving molecules/energetic molecule leave the surface without the temperature reaching its boiling point.

• The greater the surface area, the more the evaporation of particles.

• Evaporation occurs at surface of liquid: no bubbles.
• Boiling occurs throughout the liquid: bubbles appear.
• We feel cold after bath because the high energetic molecule evaporate leaving behind, dull/less energetic molecules.
• Thermal expansion: molecules gain kinetic energy and force results in pushing each other further apart.
• Volume = less area so the particles hit the walls harder and more often.
• Mercury is used to measure high temperature.
• Alcohol is used to measure low temperatures.
• The capillary tube of a thermometer is narrow so a small change in temperature results in a large change in volume of the liquid.
• Thermocouples have a low specific heat capacity this means they can measure rapidly changing temperatures and they don’t take much heat away from the object they are measuring the temperature of them.
• During melting or boiling the temperature stops rising because extra energy is needed, which is taken from the heat source, to overcome the strong forces of attraction which are holding the molecules together. This energy will not increase the speed of the molecules it will only break the bonds.
• In an experiment the value for the latent heat of fusion is too low as energy is taken in from the surroundings which melt the ice.
• In an experiment the latent heat of vaporization is too high as energy is lost to the air from the heater therefore not all the energy is used for evaporating the water.
• The value for the latent heat of vaporization is much higher than the value for fusion because a large amount of energy is needed to break the bonds between the molecules to move them far apart

• Energy= Mass x Specific heat capacity x Change in temp.
• Energy to break bonds= Mass x Latent heat of fusion/vaporization.














o Waves, Light & Sound
• Waves transfer energy from one place to another.
• There are 2 types of waves: Transverse and Longitudinal waves

• Transverse wave: A wave in which the particles vibrate perpendicular, to the direction of movement. A complete wave consists of 1 crust and 1 trough. E.g. Light waves

• Longitudinal wave: A wave in which the particles vibrate back and forth in the direction of movement. It consists of compressions and rarefactions. E.g. Sound waves

• Compressions are the area in a wave where the particles are closer to each other and the pressure in that area is highest.

• Rarefactions are the area in a wave in which the particles are far apart and the pressure is least.

• The larger the frequency and amplitude the greater the energy of the wave.
• When a wave gets refracted, its Speed decreases, Wavelength decreases, Frequency = Same.
• When a wave gets reflected, it’s Speed = Same, Wavelength = Same, Frequency = Same.
• When a wave gets diffracted, it’s Speed = Same, Wavelength = Same, Frequency = Same.
• Radio waves are easily diffracted because they have a large wavelength.
• In the spectrum of light all the colors have the same speed, but different wavelengths & frequencies.
• Objects that produce light are called luminous objects and the object which uses the light from source to reflect and make it see is called illuminated objects.
• When a light wave travels from a less dense material to a more dense material, the refractive index is more than 1.
• When a light wave travels from a more dense material to a less dense material, the refractive index is less than 1.
• A fish in a pond appears to be higher than it actually is because light refracts.

• Total incidence angle is always = Total reflection.

• Refractive index = speed of light in air/speed of light in that material.

• Remember that when the ray is passing from less dense to more dense the formula applied is Refractive index = sin i/ sin r

• But when it passes from more dense to less dense we use Refractive index = sin r/ sin i.

• Reflective index = 1/sin C (C stands for critical angle).
• Total internal reflection is when the ray is travelling to a less dense material from a more dense material and also if the incidence angle is above 42 degrees.

• The center of a lens is called its optical center, C.
• The line through C at right angles to the lens is called the principle axis.
• The fatter the lens, the stronger it is and the shorter its focal length.
• Parallel light, e.g. Sun, must be used to find the focal length of a lens.
• When the object is beyond 2F the image comes in between F and 2F, real, inverted and smaller than the object.

• When the object is in between F and 2F the image comes beyond 2F, real, inverted and same size as the object.

• When the object is before F the image appears in, real, inverted and smaller than the object.

• Dispersion of white light occurs because each fraction of white light has a different wavelength, so they are slowed down by different amounts.
• A spring is used to represent longitudinal waves.
The speed of sound in:
Air 330 m/s
Water 1400 m/s
Wood 4000 m/s
• Ripple tank can be used to see transverse wave.
• When a loudspeaker moves out the air is compressed, when it moves in the air is rarefied.
• Frequency = number of vibrations per second.

• Speed (m/s) = Frequency (Hz) x Wavelength (m)
• The speed of sound increases as the particles move closer together.
• Gamma Rays, X-Rays, Ultra-Violet are Carcinogenic.
Wave Use

1.Gamma Raysà Sterilize food & equipment, Treat Cancer 2.X-Raysà Go through body to check for broken bones
3.Ultra-Violet à Suntan, Make fluorescent materials glow
4.Light à Allows you to see
5.Infrared à Heating, Remote Control, Mobile phones, Night sight
6.Microwaves à Send messages, Cook food
7.Radio & T.V. à Send messages

LIKE IF I HELPED
Click to expand...
chill cud jz let me kno if u hav notes for chem u kno?...really Allah will bless u!
 
The Chill Master

The Chill Master

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GENERAL RULES FOR DOING PHYSICS EXAM PAPERS
  1. Read all of the parts of a question before answering it.
  2. Pay attention to the number of marks on offer (eg for 3 marks, you must say at least three things).
  3. 1 mark questions saying 'State' or 'Recall' require short, simple answers.
  4. Learn all definitions and formulas word-for-word.
  5. Give enough detail in your answers. State the obvious eg a force is a push or a pull.
  6. Show that you can use Physics vocabulary whenever you can.
  7. Note the action words in the question (and answer accordingly): State; Explain; Complete; Describe; Use (the graph); Suggest; Evaluate
  8. Part questions are usually on a single topic eg the answer to part (a) feeds into (b).
  9. Stay aware of the time (1 mark per minute). If you get stuck, move on and return if you have time at the end.
  10. Don't be afraid to physically act out the electromagnetism hand rules in the exam.
  11. Never leave a question blank. If nothing else, write down relevant formulas or definitions.
  12. As you finish a question, quickly re-read your answer to make sure it makes sense.
  13. Don't leave early. Check and re-check your answers.
  14. After the exam, don't waste time discussing your answers. Look ahead to the next paper.
Calculations: always show your working: there are many marks for this even if the answer is wrong.
These are the stages: Formula - Rearrange - Information - Substitute - Calculate - Answer - Unit
Underline: Show your final answer clearly highlighting or underlining.
Significant figures: There are marks for getting this right. Every answer should be given to the correct number of sf (the same sf as the numbers given in the question). eg 5.2*9.8 = 51 (2 sf). It is a good idea to state the sf to show that you know about it.
Equations: if you are asked to write one down, use words not just symbols.
Rounding: if you are asked to show a quantity is 'approximately equal to' a given value, show the rounding step: eg 8.7A (rounded to 9A).
Prefixes: convert units such as kN (kilo-newtons) and mA (milli-amperes) by multiplying or dividing by 1000.
Assumptions: many formulas can only be used with particular assumptions eg a fixed mass of gas or temperature is kept constant etc.
Common-sense: consider whether numerical answers make sense eg a person of mass 5.0 or 500 kg is not likely.

Graphs are often marked for the following features:
  • Size (more than 50% of the graph paper)
  • Axis (label quantity and unit; numbers evenly spaced)
  • Plotting (usually 2 marks for accuracy of points). Mark points with small dots.
  • Line of best fit (don't join the dots; don't force it through the origin; only draw a straight line if it looks straight; and if it is straight, use a ruler).
  • Anomalies can be identified as points far from the line of best fit.
Calculating gradient: actually draw the rise-run triangle (make it large). Use measurements of the triangle for the calculation, NOT values from the coordinates. A gradient has a unit.

Proportional quantities: state that a relationship is proportional or linear if A = kB, but not if A = kB + C or if A = kB2. Example: "kinetic energy increases with velocity, but the KE-v graph is non-linear (KE is prop. to v squared)".

Questions about experimental skills
Method: describe all the steps in the right order.
Quantities: give the number and unit (in a table, unit is in the heading).
Repeat readings. The reasons for this are:
  • make the result more reliable (gives the same result each time);
  • to find a mean value;
  • to spot anomalies.
Scales:read them with your eye level with the reading (avoid parallax error).

Zero error: make sure the ruler or meter starts at zero.
Apparatus: learn the names eg measuring cylinder; ray box; ticker-timer; air-track; stand and clamp etc

Examples of Safety precautions
Weights must not fall on toes.
Hot objects must be carried with insulating handles.
Fasten clamp stands to the bench.
Protect eyes from stretched wires; liquids; flying objects.
Lab-coats protect skin and clothes from chemicals and hot materials.
Electricity supplies should be low voltage.
Mop up water if it is spilled.
Radioactive materials must be stored inside lead containers and handled with forceps.
Avoid damage to apparatus (don't exceed limits for elasticity/ current/ temperature/ force etc).

Variables
Independent variable is the one which you choose to change. You can make decisions about the range and number of values. It should be the leftmost column in a table and the horizontal axis on a graph.
Dependent variable is the one which you measure. This is the variable you average when there are repetitions.
Controlled variables are the ones you keep constant to ensure a fair test.

Evaluating conclusions
Precision - this means how many significant figures are used in a measurement. (eg 0.25s has a precision of 0.01s). It can be useful to estimate the precision as a percentage of the reading (eg here it is 4%)
Accuracy - this means how close to the true value the result is.
Reliability - whether a result can be repeated.

Improvements
Reaction time - this can adversely affect measurements of time (add 0.1s). To reduce it, use electronic timing or measurelonger times.
For oscillations, measure several and divide to find time period which will reduce effect of reaction time.
To improve precision you can use a scale with smaller divisions.
Repeat measurement (consider if it is appropriate in each situation).
Does the question require improvement in the method (same apparatus used differently) or equipment (same method, different instruments)?

Explanations
When explaining, give reasons.
Use labelled diagrams if it helps you to explain something.
Mention all of the relevant physics vocabulary.
When explaining a quantity, consider the relevant formulas: eg pressure depends force exerted on an area.
In questions about kinetic theory, talk about particles.


Diagrams
Use a ruler and pencil. Don't rush. Draw large and clearly.
For magnetic fields, the lines must show the direction, form complete loops and NEVER cross nor touch.
In light diagrams, draw the normal and arrows on the rays. Light travels into the eye.
In electric circuits, show conventional current.
Post your tips below :)
THese notes are by areebaization helped my thought i can share
 
I

Imanlak

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The Chill Master said:
The spark counter: The Alpha source ionizes the air, the positive ions move towards the cathode and the negative ions move towards the anode, so a spark is produced. Only works with alpha as they are excellent in ionizing.
• Geiger-Muller tube: Works the same way as the spark counter but can detect all types of radiation. Thin Mica window so alpha radiation can pass through; a large potential difference is needed so that there is an anode and a cathode to attract the charges. To differentiate between different types of radiation, the count of pulses is recorded and is transferred to a scaler or ratemeter.

Safety Precautions;
• Keep all radioactive materials in sealed containers made of thick lead.
• Keep as far away from radioactive source as possible and use tongs.
• Waste radioactive products are either buried underground or under the sea.
• Keep exposure time as short as possible.
• Don’t eat or drink near a radioactive substance.
• Label radioactive sources with radioactive sign.
• Wear a radioactive badge: Hole to detect alpha, Aluminum to detect beta, Lead to detect gamma.
• Half-life is not affected by temperature, pressure or chemical reactions.

Radioactivity Uses:
Detect cracks in underground pipes, Thickness control in paper industry, Long half-life to keep activity constant
Sterilizing equipment in hospitals, Smoke detector, to keep activity constant and detectors will last longer

Smoke Detectors:
Alpha radiation ionizes the air, therefore a sensor detects radiation. Smoke reduces radiation and the sensor turns the alarm on.
Click to expand...
thank you
!!!
 
F

Faiza Anwar

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The Chill Master said:
PHYSICS notes


o General physics

• The density of an object only changes when the substance is heated or cooled.
• An object sinks if its density is more than the liquid on which it is placed on, but floats if less dense.
• When there is no air resistance the acceleration of any object is constant (constant= 10m/s)
• Easier to lift an object on the moon because gravity is less on the moon.
• Resultant Force.
• Gravitational, electrostatic and magnetic forces can be applied from a distance, other than that you have to be in contact with the object to apply a force.
• A force applied on an object can cause a change in speed, direction and shape.
• Acceleration, velocity etc. is a vector quantity.
• When an object moves in a circle it is accelerating and at constant speed at the same time; because the direction is changing but the speed is constant.
• Centripetal force is caused by tension in the string (ball on a string), gravity (satellite in space), friction between the tires and the road (a car on the road).
• For an object to be in equilibrium state the resultant force has to be equal or zero (forces up = forces down) and the resultant moment has to equal zero (clockwise moment = anticlockwise moment).
• For the stability of an object it has to have a wide base and a low center of mass.
• To find the center of mass draw two points A and B, hang the object from each hole so that it can swing freely. Tie a weight to each point then draw the vertical line, the center of gravity is where the lines intersect.
• When a car is going up a hill K.E. = Same, G.P.E = Increases, Chemical Energy (petrol) = Decreases and the total energy stays the same as energy is not lost, created or destroyed.
• Internal energy = Thermal energy.
• Fission = Process called when large molecules break down into small. Example: power station of uranium.

• Fusion = Process called when small molecules builds into large molecule. The fusion process produces more energy than fission. Example: Sun.
• The mass lost is converted into heat energy.
• In barometers the space at the top is a vacuum, because air would prevent the mercury from rising.
• The width of the barometer does not affect the height of mercury.
• Water manometers are more accurate to measure gas pressure.
• To get the total pressure, remember to add the atmospheric pressure.
• The gas pressure can be converted from mm of Hg to Pa by using P = density*gravity*height, but remember to use the total pressure.

• Pressure= force/area

• The more the area, the more the force & the less the area the, the less the force.







Thermal Physics
• The pressure is the same on all the walls of the containers as the molecules move in a random motion.

• Temperature is proportional to K.E. + Molecules hit the walls harder and more often.

• Brownian motion: The tiny, fast-moving air molecules, which are in a constant random motion, are hitting the larger smoke particles from all directions.

• Evaporation: It is the vaporization of liquid, when the fast moving molecules/energetic molecule leave the surface without the temperature reaching its boiling point.

• The greater the surface area, the more the evaporation of particles.

• Evaporation occurs at surface of liquid: no bubbles.
• Boiling occurs throughout the liquid: bubbles appear.
• We feel cold after bath because the high energetic molecule evaporate leaving behind, dull/less energetic molecules.
• Thermal expansion: molecules gain kinetic energy and force results in pushing each other further apart.
• Volume = less area so the particles hit the walls harder and more often.
• Mercury is used to measure high temperature.
• Alcohol is used to measure low temperatures.
• The capillary tube of a thermometer is narrow so a small change in temperature results in a large change in volume of the liquid.
• Thermocouples have a low specific heat capacity this means they can measure rapidly changing temperatures and they don’t take much heat away from the object they are measuring the temperature of them.
• During melting or boiling the temperature stops rising because extra energy is needed, which is taken from the heat source, to overcome the strong forces of attraction which are holding the molecules together. This energy will not increase the speed of the molecules it will only break the bonds.
• In an experiment the value for the latent heat of fusion is too low as energy is taken in from the surroundings which melt the ice.
• In an experiment the latent heat of vaporization is too high as energy is lost to the air from the heater therefore not all the energy is used for evaporating the water.
• The value for the latent heat of vaporization is much higher than the value for fusion because a large amount of energy is needed to break the bonds between the molecules to move them far apart

• Energy= Mass x Specific heat capacity x Change in temp.
• Energy to break bonds= Mass x Latent heat of fusion/vaporization.














o Waves, Light & Sound
• Waves transfer energy from one place to another.
• There are 2 types of waves: Transverse and Longitudinal waves

• Transverse wave: A wave in which the particles vibrate perpendicular, to the direction of movement. A complete wave consists of 1 crust and 1 trough. E.g. Light waves

• Longitudinal wave: A wave in which the particles vibrate back and forth in the direction of movement. It consists of compressions and rarefactions. E.g. Sound waves

• Compressions are the area in a wave where the particles are closer to each other and the pressure in that area is highest.

• Rarefactions are the area in a wave in which the particles are far apart and the pressure is least.

• The larger the frequency and amplitude the greater the energy of the wave.
• When a wave gets refracted, its Speed decreases, Wavelength decreases, Frequency = Same.
• When a wave gets reflected, it’s Speed = Same, Wavelength = Same, Frequency = Same.
• When a wave gets diffracted, it’s Speed = Same, Wavelength = Same, Frequency = Same.
• Radio waves are easily diffracted because they have a large wavelength.
• In the spectrum of light all the colors have the same speed, but different wavelengths & frequencies.
• Objects that produce light are called luminous objects and the object which uses the light from source to reflect and make it see is called illuminated objects.
• When a light wave travels from a less dense material to a more dense material, the refractive index is more than 1.
• When a light wave travels from a more dense material to a less dense material, the refractive index is less than 1.
• A fish in a pond appears to be higher than it actually is because light refracts.

• Total incidence angle is always = Total reflection.

• Refractive index = speed of light in air/speed of light in that material.

• Remember that when the ray is passing from less dense to more dense the formula applied is Refractive index = sin i/ sin r

• But when it passes from more dense to less dense we use Refractive index = sin r/ sin i.

• Reflective index = 1/sin C (C stands for critical angle).
• Total internal reflection is when the ray is travelling to a less dense material from a more dense material and also if the incidence angle is above 42 degrees.

• The center of a lens is called its optical center, C.
• The line through C at right angles to the lens is called the principle axis.
• The fatter the lens, the stronger it is and the shorter its focal length.
• Parallel light, e.g. Sun, must be used to find the focal length of a lens.
• When the object is beyond 2F the image comes in between F and 2F, real, inverted and smaller than the object.

• When the object is in between F and 2F the image comes beyond 2F, real, inverted and same size as the object.

• When the object is before F the image appears in, real, inverted and smaller than the object.

• Dispersion of white light occurs because each fraction of white light has a different wavelength, so they are slowed down by different amounts.
• A spring is used to represent longitudinal waves.
The speed of sound in:
Air 330 m/s
Water 1400 m/s
Wood 4000 m/s
• Ripple tank can be used to see transverse wave.
• When a loudspeaker moves out the air is compressed, when it moves in the air is rarefied.
• Frequency = number of vibrations per second.

• Speed (m/s) = Frequency (Hz) x Wavelength (m)
• The speed of sound increases as the particles move closer together.
• Gamma Rays, X-Rays, Ultra-Violet are Carcinogenic.
Wave Use

1.Gamma Raysà Sterilize food & equipment, Treat Cancer 2.X-Raysà Go through body to check for broken bones
3.Ultra-Violet à Suntan, Make fluorescent materials glow
4.Light à Allows you to see
5.Infrared à Heating, Remote Control, Mobile phones, Night sight
6.Microwaves à Send messages, Cook food
7.Radio & T.V. à Send messages

LIKE IF I HELPED
Click to expand...
GREAT!!
 
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