AQA GCSE Design and Technology 8552 1 Forces

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AQA GCSE Design and Technology 8552 1 Forces and stresses on materials Unit 4

AQA GCSE Design and Technology 8552 1 Forces and stresses on materials Unit 4 Common specialist technical principles

Objectives • Be able to recognise and characterise tension, compression, bending, torsion and shear

Objectives • Be able to recognise and characterise tension, compression, bending, torsion and shear forces and stresses • Understand the impact of different forces and stresses on materials

Forces and stresses on materials and objects Unit 4 Common specialist technical principles Starter

Forces and stresses on materials and objects Unit 4 Common specialist technical principles Starter • Designers need to consider the forces and stresses that every product will need to withstand • This enables products to function correctly • What forces are acting on this balloon and the air inside it? • What forces are acting on the ribbon? • Are there more formal definitions for these forces?

Forces and stresses on materials and objects Unit 4 Common specialist technical principles Forces

Forces and stresses on materials and objects Unit 4 Common specialist technical principles Forces and stresses • All materials, structures and products have to withstand various stresses as forces are applied • These forces include: • Tension • Compression • Torsion • Bending • Shear

Forces and stresses on materials and objects Unit 4 Common specialist technical principles Static

Forces and stresses on materials and objects Unit 4 Common specialist technical principles Static and dynamic loads • A static load does not move and will exert far less stress than a dynamic load • What force(s) are swing ropes subject to? • When are the ropes under the greatest stress given an identical load?

Forces and stresses on materials and objects Unit 4 Common specialist technical principles Force

Forces and stresses on materials and objects Unit 4 Common specialist technical principles Force = Mass x Acceleration • Designers have to consider the speed behind the force as well as the type of force • If you jumped on an icy pond, would it be more or less likely to crack than if you stood on it?

Forces and stresses on materials and objects Unit 4 Common specialist technical principles Tension

Forces and stresses on materials and objects Unit 4 Common specialist technical principles Tension • Helicopter blades are under tension when the rotor spins • They need to have high tensile strength to withstand these forces • How would you define tensile strength? • Suggest three other examples of components experiencing tension?

Forces and stresses on materials and objects Unit 4 Common specialist technical principles Compression

Forces and stresses on materials and objects Unit 4 Common specialist technical principles Compression • The impact of a car crash exerts compressive force on the vehicle • How would you define compressive strength? • How is a car designed to handle compression? • How is compression used with gases?

Forces and stresses on materials and objects Unit 4 Common specialist technical principles Torsion

Forces and stresses on materials and objects Unit 4 Common specialist technical principles Torsion • Twisting a material puts it under torsion • What are the similarities and differences between tension and torsion? • How is a screwdriver blade subject to torsion? • What is a functionally acceptable level of torsional strength for a screwdriver? • How might a vehicle chassis experience torsion?

Forces and stresses on materials and objects Unit 4 Common specialist technical principles Bending

Forces and stresses on materials and objects Unit 4 Common specialist technical principles Bending • Stiffness is the ability of a material to resist being bent out of shape • Some products and materials are designed to have a certain degree of stiffness to perform their function • How do tension and compression exert themselves on either side of a bending pole?

Forces and stresses on materials and objects Unit 4 Common specialist technical principles Shear

Forces and stresses on materials and objects Unit 4 Common specialist technical principles Shear • A shear force occurs when opposite forces act on an object in a direction perpendicular to its length • Which part of these garden shears is perpendicular to the force of the handles? • Which part has to withstand the most shear force? • How is the nail in a picture hook under shear force? • Give two other examples of shear forces in action?

Forces and stresses on materials and objects Unit 4 Common specialist technical principles Defining

Forces and stresses on materials and objects Unit 4 Common specialist technical principles Defining forces • Work in pairs to define these five key forces:

Forces and stresses on materials and objects Unit 4 Common specialist technical principles Worksheet

Forces and stresses on materials and objects Unit 4 Common specialist technical principles Worksheet 1 • Complete Task 1 of the worksheet

Forces and stresses on materials and objects Unit 4 Common specialist technical principles Forces

Forces and stresses on materials and objects Unit 4 Common specialist technical principles Forces and materials • Different materials and components are chosen for their ability to withstand certain forces • Why is a plastic pot more resistant to compressive or shear forces than a ceramic pot?

Forces and stresses on materials and objects Unit 4 Common specialist technical principles Worksheet

Forces and stresses on materials and objects Unit 4 Common specialist technical principles Worksheet Task 2 • Exert different forces on two different materials and record your findings on a radar chart

Forces and stresses on materials and objects Unit 4 Common specialist technical principles Plenary

Forces and stresses on materials and objects Unit 4 Common specialist technical principles Plenary • Complete Task 3 of the worksheet • Explain how a skateboard is designed to withstand each of the following forces? • Tension • Compression • Torsion • Bending • Shear

Forces and stresses on materials and objects Unit 4 Common specialist technical principles Copyright

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