Get to work! Unit P2a Topic 10 Lesson 1 Specification reference Other lessons in this book P2.10.4 Explain that work done is equal to energy P2: 9.6 Falling down transferred. P2.10.6 Use the equation: work done force distance moved in the direction of the force W F s. Student Book pages to 218 to 219 Worksheet P2: 10.1(1) Worksheet P2: 10.1(2) Technician’s notes P2: 10.1 distance force joule mass energy transfer gravitational potential kinetic energy work done energy Resources Review mass and weight. Pupils use the worksheet to revise the distinction between mass and weight. Worksheet P2: 10.1(1) Review types of energy and energy transfers using a series of short demonstrations. Technician’s notes P2: 10.1 Learning outcomes that an object can be acted on by different types of force and these will have different values that work done is equal to the energy transferred Teaching and learning activities Resources Pupils compare the force needed to drag several objects with the force needed to lift them. Technician’s notes P2: 10.1 Pupils can use objects of their choice, e.g. pencil cases, shoes or use objects provided. Ask pupils to identify describe the energy transfers in each case. Ask the pupils to answer questions 1 to 4 from the Student Book. Student Book page 218 Go through the answers. Learning outcomes state that work done force distance moved in the direction of the force use the equation work done force distance moved in the direction of the force WFs Teaching and learning activities Resources Compare work done in lifting an object up and dragging it up a slope to the same height. Technician’s notes P2: 10.1 Ask pupils to explain: why a smaller force is needed to drag the object than lift it why using this smaller force results in more work being done overall why dragging up a slope might be the better method even if there is more work done overall. Ask the pupils to answer questions 5 and 6 from the Student Book. Student Book page 219 Go through the answers. Learning outcomes use the equation in a changing force context Teaching and learning activities Resources Pupils do the stretching spring experiment using worksheet P2: 10.1(2) to guide them. They Worksheet P2: 10.1(2) plot the graph and calculate the energy stored in the spring at a particular extension. The experiment can be limited to loads that will not exceed the elastic limit of the spring (and Technician’s notes P2: 10:1 therefore permanently stretch it) and the area to be calculated will be a triangle. If pupils exceed the elastic limit, they will have to measure the area by counting squares. Ask pupils to answer question 7 from the Student Book. Go through the answers. Student Book page 219 Ask pupils to indicate ‘Yes’ or ‘No’ for each of the following in answer to the question ‘Is this an example of doing work?’. – reading a book for English (no) – putting a jar of jam back on a shelf (yes) – going to bed (yes) – doing research using the Internet (no) – playing football (yes) Ask pupils to suggest one energy transfer where work is done and one energy transfer where no work is done. Collect responses to create two lists. LOW DEMAND STANDARD DEMAND HIGH DEMAND 5 a Weight 1.5 kg 10 m/s 15 N 7 a 300 N 1.6 m 480 J 2 1 The construction worker is doing the most work b 15 N 1.2 m 18 J b 100 N 5 m 500 J 2 Jack does the most work. c 20 18 360 J c Some energy is wasted due to 3 Wayne does the most work. frictional forces. 6 a 600 N 0.15 m 90 J 4 Only movement can count as work. d Amanda might not be able to lift You will not have moved much, and b 20 90 1800 J the wheelbarrow straight up. will have used very little force to do so.