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# Topic 3 year 8 physics

 Physics Topic Forces 2 (Contact Forces and Pressure) No of lessons 11 When is it happening Year 8 Term 3 What will students learn Students should be able to define the term contact force and give examples of these type of forces, and draw a series of diagrams showing the size and direction of forces acting on a series of objects.  They should be able to draw graphs to show linear and non-linear relationships. Students should explain and give examples of the terms deformation, tension and compression, and explain how different materials behave under tension or compression. They should define the terms friction and drag and explain the effect on a moving and non moving object of a resultant force of zero. Explain how forces can change an object’s form causing it to be stretched or compressed and that in some materials, deformation is proportional to force applied and is a linear relationship and therefore explain the effect of a change in force on the length of a spring. Students should compare the behaviour of different materials in deformation using the idea of proportionality. They should explain the factors which affect the size of frictional and drag forces, including the effects of drag and other forces on falling or accelerating objects as they move.  Research Hooke’s Law and  methods of reducing drag when swimming. Evaluate how well sports or vehicle technology reduces frictional or drag forces.  Explain how the effect of a force differs depending on the area over which the force applies, Explain, with examples how pressure acts in a fluid in all directions and increases with depth. Describe atmospheric pressure as the pressure caused by the weight of the air above a surface. Draw annotated diagrams to explain the behaviour of fluids in a variety of different situations where the pressure is unequal. Apply the formula: fluid pressure, or stress on a surface = force (N)/area (m2). Use stress to deduce potential damage to one solid object by another. Explain underwater effects using the concept of changing pressure. Carry out calculations involving pressure, force and area in hydraulics. Use the fluid pressure / stress formula to find force and area. Key Knowledge that students should know at the end of 'Topic' This is the knowledge that students will meet for the first time in this topic Students will define contact force and give examples. Students should explain and give examples of the terms deformation, tension and compression, and explain how different materials behave under tension or compression. They should define the terms friction and drag and explain the effect on a moving and non moving object of a resultant force of zero. Explain how forces can change an object’s form causing it to be stretched or compressed. They should explain the factors which affect the size of frictional and drag forces, including the effects of drag and other forces on falling or accelerating objects as they move. Explain how the effect of a force differs depending on the area over which the force applies, Explain, with examples how pressure acts in a fluid in all directions and increases with depth. Describe atmospheric pressure as the pressure caused by the weight of the air above a surface. Know the formula: fluid pressure, or stress on a surface = force/area. Use stress to deduce potential damage to one solid object by another. Explain underwater effects using the concept of changing pressure. Carry out calculations involving pressure, force and area in hydraulics. Use the fluid pressure / stress formula to find force and area. This is knowledge that students may have met before but will need to deepen their understanding From KS2 - Students should be able to compare how things move on different surfaces, notice that some forces need contact between 2 objects, but magnetic forces can act at a distance. Students can observe how magnets attract or repel each other. Students should be able to explain that unsupported objects fall towards the Earth because of the force of gravity acting between the Earth and the falling object. Students should identify the effects of air resistance, water resistance and friction, that act between moving surfaces and recognise that some mechanisms including levers, pulleys and gears allow a smaller force to have a greater effect.  From Forces 1 - Differentiate contact and non-contact forces. Unsupported objects fall towards the Earth because of the force of gravity, students will be able to quantify this. Key Skills that students should be able to demonstrate at the end of 'Topic' This is the skills  that students will meet for the first time in this topic They should be able to draw graphs to show linear and non-linear relationships. Students should compare the behaviour of different materials in deformation using the idea of proportionality. Hooke’s Law. Apply and rearrange the equations Stress=Force/Area and Pressure=Force/Surface Area This is skills that students may have met before but will need to develop Manipulate the equations Stress=Force/Area and Pressure=Force/Surface Area Key vocabulary that students should know and understand Resultant force, opposite, shape, equilibrium, contact, non-contact, action, deformation, tension, compression, independent variable, dependent variable, linear relationship, directly proportional,  drag, fluid, streamlining, lever, upwards, pressure, stress, upthrust, float, sink, atmospheric pressure, hydraulic, incompressible The Big Question How do Force and Pressure affect solid objects and fluids? Key questions that students should be able to answer at the end of the 'Topic' What happens when you combine forces? How do Forces change the shapes of objects? How do frictional forces affect the motion of objects? How can we use frictional forces to help travel? How can we predict if something will sink or float? How can we calculate if something will fall through ice (or a roof) How can we make air collapse a can? How do Hydraulic Brakes work? What is upthrust and how can we measure it?