General Mechanics/Force and Motion

Year 10 Force and Work 7 periods Possible Approach: Lesson Suggested Learning Outcomes Course Outline Resources 1 – 3  Recognise that unbalanced forces cause acceleration.  Investigate the relationship between the unbalanced force acting on an object, is mass *and acceleration: Newton’s Second Law. (Use Fnet = ma giving correct units for all quantities) •**Reinforce ideas about force causing acceleration (= the rate at which speed changes) Experiment 1: Finding the force required to move an object (static friction) Discuss the factors that may affect the frictional forces acting on the block (e.g. load on *the block, surface area in contact with the bench, type of the surfaces in contact …) Attach a force meter to a block at rest on the bench. Pull the force meter and slowly increase *the force until the block just begins to move – record the force meter reading, tabulate data, *repeat, calculate average. [Or, use a bag to which washers may be added, attached to a cord and hanging over the end of *the bench to pull the block.] quantities and the third unknown) – a three symbol triangle may simplify the maths. Homework: Coursebook – Newton’s second Law force (e.g. when a force acts on a body, it moves faster and kinetic energy increases) • Introduce the relationship between energy transferred and work done. • Define work done in terms of the applied force and the distance through which this ********force acts (Work done = force x distance) • Use the work rule to calculate work / force / distance (given two quantities and the ********third unknown) – a three symbol triangle may simplify the maths Homework: Coursebook – Work Done and Energy 6 – 7  Investigate and describe the pattern of results formed from graphing ************************the effects of applied forces on a spring. Explore the relationships between science and technology by investigating the application of *science to technology and the impact of technology on science, e.g. Archimedes’ screw to *illustrate the principle of oits use in water irrigation or the use of springs and similar *propulsion devices in toys Experiment 4: Stretching Springs Hang a spring vertically using a clamp and stand. Add weights to the end of the spring, *measure the length of the spring after each additional weight is added. Calculate the *extension (Note: some initial weight will probably need to be added before the spring *stretches at all) Graph extension vs applied force. Interpret the graph, e.g. find the *extension for unit applied force or applied force per unit extension. Investigate and understand the turning effect of a force. Calculate the turning effect of a force = F x d where force (F) and distance (d) are *********at right angles. Use the lever rule: F1d1 = F2d2 • Discuss and brainstorm ideas about what causes things to turn about a pivot (fulcrum). • Introduce the concept of the turning effect of a force (torque). • Discuss the concept levers – to increase the turning effect, use a greater distance *******(e.g. a long crowbar) and/or a greater force (e.g. a heavier weight) • Use the lever rule to calculate forces and distances at right angles to the applied ********force (given three quantities and the fourth unknown). Experiment 5: The turning effect of a force Kit available from the science Office • Homework: Coursebook – The Turning Effect of a Force Extension