Stress, strain and plastic deformation properties are used in the design of machine components such as gears, chains, and machine columns. Light waves are transverse waves, where particles of the wave oscillate in a line at right angles to the direction of travel in a light beam there are many waves with lines of oscillation set at random angles. Using the following information on stress and strain, plot a graph in excel to determine the youngs modulus for an unknown material. The extension of a wire under tension may be measured using searles apparatus. Pa n m2 strain no units elastic strain energy is the area below a forceextension graph. But if you do alevel maths you can do up to 4 mechanics modules, which probably involve more mechanics than ib, although it is all mathsy mechanics. The best physics o level notes o and a level notes. Apr 01, 2015 when revising for your exams it may seem like you are under stress and strain, however, they are quite different but they do allow to investigate materials. Stress is a measure of the force applied per unit cross sectional area of a material. The ratio of stress and strain is constant with in the elastic limit. Pa, n m2 the gradient of a stressstrain graph is thus equal to the young modulus. Alevel physics definitions pdf i found this though. Alevel physics revision notes 2015 contents units, quantities and measurements. The scheme of work for chapter 1 is also available here for free and includes step by step lesson points and ideas plus links to the aqa syllabus.
Apr 22, 2019 it is defined as the ratio of tangential stress to the shearing strain, within the elastic limit. At, we provide access to the bestquality, bestvalue private tutoring service possible, tailored to your course of study. In the language of physics, two terms describe the forces on objects undergoing deformation. How much energy is stored in a 1m length of the wire when the strain is 1. The young modulus of a material is defined as the ratio of stress to strain. Worksheet, self directed study, cover lesson, homework. The stress is defined as the force applied per unit crosssectional area of the wire.
E is a constant because l, a and k are all constant. Elastic and plastic regions of deformation are indicated by the dashed line. Its unit is nm 2 or pascal and its dimensional formula is ml 1 t 2. Edexcel a level physics physics smart notes online. The relationship of stress and strain for steel can be observed in. By finding the area under a stressstrain graph, it is possible to work out the energy stored per unit volume in a material. Polarization of light, waves from alevel physics tutor. A full set of a level physics notes free to download. To compare the elastic properties of materials in a way that does not depend on the sample tested, measurements of. Direct stress strain help for sons homework show 10 more chemistry practical question has anyone received their a level remarks.
Youngs modulus is a measure of the ability of a material to withstand changes in length under lengthwise tension or compression. Youngs modulus is a measure of the stiffness of a material, and describes how much strain a material will undergo i. Youngs modulus is also termed the modulus of elasticity. It is not coincidence that the name plastic, which describes any kind of polymeric material, is similar to the word plasticity which is the propensity of a solid to undergo. External forces arise from interaction between the system of interest and its surroundings. The values for stress and strain must be taken at as low a stress level as possible, provided a difference in the length of the sample can be measured. Ap revision guide ch 4 bryanston school physics department. Use these to help revise for exams and to read through as you go along to build understanding.
They are written for the aqa exam board but should still be useful for all other exam boards, including edexcel, and ocr a and b. Edexcel a level physics students of edexcel international advanced level in physics will develop essential knowledge and understanding, including an appreciation of the link between theory and experiment, and the skills to design, execute and analyse their own investigations. Ocr as and a level physics a delivery guide understanding. Elastic strain energy yield point breaking stress plastic behaviour fracture brittle behaviour forceextension graphs energy stored stiffness strength ductile polymeric. Definitions of stress, strain and youngs modulus scool, the. Modulus of elasticity e elastic materials always spring back into shape when released. Summary tensile stress, tensile strain, strain energy, breaking stress, elastic and plastic deformations and brittle failure are important properties of a material. Elasticity is a measure of how much an object deforms strain when a given stress force is applied. The best physics as and a level notes, revision guides, tips and websites compiled from all around the world at one place for your ease so you can prepare for your tests and examinations with the satisfaction that you have the best resources available to you.
The blue graph is offered as an example of a stress vs. The ratio of extension to original length is called strain it has no units as it is a ratio of two lengths measured in metres. For a given material, youngs modulus e is the ratio of stress to strain, provided the limit of. Please note that the scheme of assessment has changed since 2005. The images produced illustrate the photoelastic behaviour of the plastic. These powerpoints cover mechanics, materials, electricity, waves, the nature of light, further mechanics, particle physics, electric and magnetic fields, astrophysics, nuclear physics. Basic concepts of stress and strain mechanics of materials describes how solid materials will deform change shape and how they will fail break when subjected to.
We can use the above definitions of stress and strain for forces causing tension or compression. A stress on a material causes a strain for a material, a stressstrain graph can be drawn. The other three types of stress, tension, compression and shear, are nonuniform, or directed, stresses. It is measured in pascals pa, or nm2, or kgm1s2 if you. The gradient of this graph is then the young modulus. The height of the water in the capillary above the level of the liquid in the.
Stressstrain relationship, hookes law, poissons ratio, shear stress, shear strain, modulus of rigidity. Simple explanations, with graphs and back up examples on. Get physics as and a level notes here at my new website. The best physics o level notes compiled from all around the world at one place for your ease so you can prepare for your tests and examinations with the satisfaction that you have the best resources available to you. When a material is elastic, it returns to its original shape on removal of the distorting force.
Revision notes for cbse class 11 physics summarise key points of a chapter in an easy to remember. Hookes law states that the extensionx of a spiral spring. Strain has no units because it is a ratio of lengths. Strain has no units due to simply being the ratio between the extension and original length of a material, so youngs modulus is measured by the same units as stress, i. As physics chapter 11 notes materials a level notes. The diagram below shows how the tensile stress varies with tensile strain. The answer lies in behaviour of materials to external. Graph the results of the experiment using the stress strain worksheet. It is not necessarily the graph profile you will obtain in your experiment. Ever wondered why, when iron rod can withstand more load, things made of glass or wood breaks easily. But it covers almost all that you need to learn to crack the edexcel as physics unit 1 and unit 2 exams. Apr 08, 2018 the best physics o level notes compiled from all around the world at one place for your ease so you can prepare for your tests and examinations with the satisfaction that you have the best resources available to you.
Particles and medical physics questions suitable for ocr a click here. Elastic strain energy, e the young modulus is a property of a material it measures stiffness. Definition of stress, stress tensor, normal and shear stresses in axially loaded members. Alevel physics help definitions and formulae sheets. A level physics solid mechanics questions aqa, ocr, edexcel. Stressstrain behavior of polymers one of the most important characteristics of polymers is their inherent toughness and resistance to fracture crack propagation. In alevel, everything you get examined on is taught, which obviously leaves there more to learn.
Objects that are very elastic like rubber have high elasticity and stretch easily. Definitions of stress, strain and youngs modulus scool. Aqa a level physics paper 1 74081 04 june 2018 exam discussion. The extension that a force produces depends on the dimensions of the sample as well as the material that it is made from. On a stress strain graph the youngs modulus is constant for the portion of the graph where hookes law applies. As a result of applying a tensile stress to an object, a tensile strain is set up within the object. This is lesson 3 of chapter 1 of my alevel physics course and is a free sample powerpoint from my entire 80 powerpoint to buy scheme of work. Hookes law, poissons ratio, shear stress lecture 5 shear strain, modulus of rigidity, bulk modulus. Physics in april module 6 pdf i will post some solutions every so often enjoy. Why is stress a property of a material rather than a property of an object.
When analyzing forces in a structure or machine, it is conventional to classify forces as external forces. See class notes for some mems applications, the beams that allow the sensor or. Suggestions for suitable practice questions from a level past papers and specimen papers. Longitudinal strain when a body is subjected to axial load p, there is an axial deformation in the length of the body. The equation below is used to calculate the stress. Examples of external forces include gravitational forces.
Stressstrain graph tables and diagrams comparing materials by properties and relating them to how materials are. External forces, constraint forces and internal forces. Polarization is the production of waves oscillating in one plane ie with one line of oscillation from a source of randomly oscillating waves. Figure2is a typical stress strain graph for a metal.
It is defined as the ratio of tangential stress to the shearing strain, within the elastic limit. Elasticity, stress, strain, and fracture boundless physics. By finding the area under a stressstrain graph, it is possible to work out the energy stored per unit volume in a material the young modulus, being a material property as it is, can. Apr 08, 2015 cambridge international as and a level physics is ideal for learners who want to study physics or a wide variety of related subjects at university or to follow a career in science. Physics notes for cbse class 11 science and short keynotes to score more marks in exams, uploaded by registered users on. To compare the elastic properties of materials in a way that does not depend on the sample tested, measurements of stress and strain are used instead of force and extension. Relationship between material properties of isotropic materials. Elasticity is a measure of the deformation of an object when a force is applied. For a clearer image of this daily revision calendar for as module 6. Replicas in clear plastic are put under stress to highlight weaknesses in molded shapes. Polarization is also used in mineralogy to identify the crystalline components of different rocks. Youngs modulus the ratio of stress and strain is constant with in the elastic limit.
Apr 01, 2015 8 videos play all behaviour of springs and materials a level physics physics online physics mechanics. Value of stress strain is a constant, known as the young modulus of the material. Edexcel as physics in 100 pages 2 preface the purpose of this book is to offer a concise and easytounderstand textbook and exam preparation guide of the edexcel as physics. Stress analysis is important in the design and manufacture of parts for industry. Stress, strain, and elastic modulus part 1 physics libretexts. Physics is the scientific study of matter and energy and how they interact with each other. From 0 to the limit of proportionality p, the tensile stress is proportional to the tensile strain. Under this circumstance, the ratio between stress and strain is constant. One type of stress is uniform, which means the force applies equally on all sides of a body of rock.
When revising for your exams it may seem like you are under stress and strain, however, they are quite different but they do allow to investigate materials. Compressibility of a material is the reciprocal of its bulk modulus of elasticity. Smart notes online provides help to the students by classifying resources, such as books, revision guides, notes, past papers, mark schemes and examiner reports. Lecture 6 numerical problems on shear strain, modulus of rigidity lecture 7 stressstrain diagram for uniaxial loading of ductile and brittle materials. The ratio of axial deformation to the original length of the body is. All rocks in the earth experience a uniform stress at all. Edexcel a level physics powerpoint slideshows and resources, covering unit 1 physics on the go, unit 2 physics at work, unit 4 physics on the move and unit 5 physics from creation to collapse. This can be easily shown by substituting for k fx into the equation for e.
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