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# Physics study

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### Physics study

1. 1. Keith Kiely Physics Study Keith Kiely 2011-2013Nov-11 Page 1
2. 2. Keith Kiely Heat and TemperatureUnit of Temperature:  Kelvin (K)Thermometric PropertiesA thermometric property is a measurable property of a body that changes thetemperatureExamples are:  The length of liquid in a tube  The resistance of a wire or a thermistor  The EMF of a thermocouple  The colour of some substances  The pressure and volume of gasHeat capacity:The heat capacity of a body is the amount of energy needed to raise the temperature ofa body by 1KThe pacific heat capacity (c) of a substance is the amount of energy needed for thetemperatureNov-11 Page 2
3. 3. Keith KielyLatent Heat:Latent heat is when heat is absorbed or released when it is in the process of changingstates.Heat Transfer:  Conduction  Convection  RadiationConduction:This is the transfer of heat within a body without the movement of particles within thebody itselfConvection:This is the transfer of heat within a body also with the movement of the particles inthe body.Radiation:Is the transfer of energy into an empty space, it is how heat and light from the sunreach earthKey Definitions:  Heat Capacity (C)  Specific Heat Capacity (c)  Latent Heat (L)  Specific Latent Heat (l)  Conduction  Convection  Radiation  Thermometric PropertiesNov-11 Page 3
4. 4. Keith Kiely MechanicsWork, Energy and Power:Work is done when a force moves an object a certain distanceWork is also the force multiplied by distanceEnergy is the ability to do workTwo forms of energy are:  Kinetic Energy (Ek)  Potential Energy (Ep)Power is:  The rate work is done  The rate at which energy is changed from one form to anotherPower is energy divided by timeLinear Motion:In mechanics we make use of:  Scalar Quantities  Vector QuantitiesScalars are quantities that only have magnitudeVectors are having both magnitude and directionNov-11 Page 4
5. 5. Keith KielyConservation of MomentumFor a collision occurring between object 1 and object 2 in an isolated system, the totalmomentum of the two objects before the collision is equal to the total momentum ofthe two objects after the collision. That is, the momentum lost by object 1 is equal tothe momentum gained by object 2.Newton’s Law of Motion: 1. A body will continue in a state of rest unless a force is upon it 2. The rate in the change of momentum depends on the force applied to it 3. If body a makes a force against another body, both bodies have an equal forceFirst Law:This is demonstrated by space travel.In the absence of air, a spacecraft traveling seven thousand meters per second can doso without engines.It will travel till a force is applied to stop itSecond Law:This is demonstrated by seat belts.When a person is thrown forward, the belt expands slightlyThis extends the time over which the person is slowing down,This decreases the value of the acceleration and reduces the forceNov-11 Page 5
6. 6. Keith KielyThird Law:Seen from a rocket when a large force towards the rear. It creates an equal butopposite force. This is why it movesCircular Motion:A body that travels an equal distance in equal amounts of time along a circular pathhas a constant speed but not constant velocity. This is because velocity is a vector andthus it has magnitude as well as directionAcceleration:This is when an object changes its direction, the velocity changes with it. It is knownas centripetal acceleration and its direction is towards the centre. It gives Rise to theCentripetal forceCentripetal acceleration:This is the acceleration of a body moving in a motion of a circle. The direction istowards the centre of the circle.Centripetal force:Is the force on a body in a circular motion and the direction is towards the centre ofthe circle.Plants and Gravity:This states that the force of attraction between any two masses is proportional to theproduct of the masses.Weight:The weight of the body is the gravitational force of the body.Nov-11 Page 6
7. 7. Keith KielySimple Harmonic Motion:It is when any motion where the acceleration is proportional to the distance from itsequibriumHooks Law:Hooke’s law is when the restoring force on a spring is the same as the extension onthe springHookes Law ApparatusNov-11 Page 7
8. 8. Keith KielyHookes Law GraphBoyles Law:States that when the temperature on a gas is constant, the pressure on its volume isproportional.Nov-11 Page 8
9. 9. Keith KielyBoyles Law ApparatusArchimedes Principle:This states that a body immersed in a fluid will have an upthrust equal to the weightMoments of a Force:The moment of a force is equal to the magnitude of the force multiplied by theperpendicular distance from the axis.The moment of a force tells us about the ability to make something turn.Nov-11 Page 9
10. 10. Keith Kiely Light, Sound and WavesReflection:The angle of incidence is equal to the angle of reflectionThe incidence ray, the normal ray and the reflected ray are all on the same planeImage Formation:A real image is formed by the insertion of light rays and can be formed by ascreenAn image is formed by this insertion of light rays and can’t be formed on a screenCurved Mirrors:A light ray parallel to the principle axis is reflected trough the focal pointA light ray through the focal point reflects parallel to the axis.A light ray incident at the pole clearly reflects according to the laws of reflectionNov-11 Page 10
11. 11. Keith KielyRefraction:Laws of Refraction:  The incident ray, the normal ray and the refracted ray are all in the same plane  For any pair of media, the angle of the incidence is proportional to the angle of refraction.  When light moves from a low dense medium to a more dense medium it bends to the normal  If it moves into a denser medium it moves away from the normal. Refraction is caused by the change in the speed of light.Reflection:  The Internal Reflection occurs when the angle of incidence in a dense material is greater than the critical angle and light is reflected back into the original material.  The critical angle is the angle of incidence of where the corresponding angle or refraction is 90˚Nov-11 Page 11
12. 12. Keith KielyConverging Lenses:The light is refracted inward on both entering and leaving lenses. This causes theconverging effect. All the light that hits the lens passes through the single pointknown as the vocal pointDiverging Lenses:A lens that causes a beam of parallel rays to diverge afterrefraction, as from a virtualimage; a lens that has a negative focal length.Waves:Doppler Effect is the apparent change in the frequency of a wave because of relativemotion between the observer and the sourceA redshift is a shift in the frequency of a photon toward lower energy, or longerNov-11 Page 12
13. 13. Keith Kielywavelength. The redshift is defined as the change in the wavelength of the lightdivided by the rest wavelength of the light.The Doppler Redshift results from the relative motion of the light emitting object andthe observer. If the source of light is moving away from you then the wavelength ofthe light is stretched out, i.e., the light is shifted towards the red. These effects,individually called the blueshift and the redshift are together known as Doppler shiftsNov-11 Page 13