P5.1 Work done
Navigate to resources by choosing units within one of the unit groups shown below.
Delivery guides are designed to represent a body of knowledge about teaching a particular topic and contain:
- Content: A clear outline of the content covered by the delivery guide;
- Thinking Conceptually: Expert guidance on the key concepts involved, common difficulties students may have, approaches to teaching that can help students understand these concepts and how this topic links conceptually to other areas of the subject;
- Thinking Contextually: A range of suggested teaching activities using a variety of themes so that different activities can be selected which best suit particular classes, learning styles or teaching approaches.
P5.1 Work done
Assessable content statements:
P5.1a describe for situations where there are energy transfers in a system, that there is no net change to the total energy of a closed system (qualitative only)
P5.1b describe all the changes involved in the way energy is stored when a system changes for common situations
P5.1c describe the changes in energy involved when a system is changed by heating (in terms of temperature change and specific heat capacity), by work done by forces, and by work done when a current flows
P5.1d make calculations of the energy changes associated with changes in a system, recalling or selecting the relevant equations for mechanical, electrical, and thermal processes; thereby express in quantitative form and on a common scale the overall redistribution of energy in the system (M1a, M1c, M3c)
P5.1e calculate the amounts of energy associated with a moving body, a stretched spring and an object raised above ground level
A variety of engaging and exciting quizzes to test learners’ knowledge on the topic.
There are premade quizzes and learners compare their scores with others.
When teaching ‘work done’ it is good to build on learner’s prior knowledge in Key Stage3. P5.1a can be introduced by asking learners why their houses are insulated. Direct learners to the idea of conserving heat (energy), and then introduce them to the concept of a closed system. Define it as a ‘system in which nothing from the outside affects it and nothing from inside the system affects anything outside the system’.
When people insulate their homes they are trying to creating a closed system where the energy remains constant. The energy will change from one form to another but will not leave the system, this of course isn’t practically possible to achieve completely. The law of conservation of energy can be introduced with examples.
P5.1b can be taught in a practical way by using Learner resource 1 and setting up a circus of activities, which focuses on energy transformation (see also Teacher resource 1. Learners move around the room and identify the energy transformations that are occurring in each station. Learners complete the table.
Ask learners to pick up an object near to them and lift it up by a meter. Explain that they have just done work and explain that when a force is used to move an object work is done (P5.1c, e). This can be taken further by carrying out a class practical in which learners have to walk from the front of the class to the back. Ask learners firstly what energy transformations are occurring and then to calculate their work done. Learner resource 2 can be used (see also Teacher resource 2).
An introductory approach to work done, power, gravitational potential energy and kinetic energy (P5.1d,e) is to pair learners up and provide each group with a sheet containing several scenarios which require learners to apply the equations relating to the above terms. Learners can be taken to the playing fields and asked to run 100 m and time how long it takes. They may be able to calculate their kinetic energy.
Common misconceptions or difficulties students may have
Learners find it hard to understand that if energy is conserved why are we running out of it. Energy is conserved in closed system but in the real world technically there is no closed system. Provide learners with an outline of a human torso and get learners to label where they get their energy (Learner resource 3 and Teacher resource 3). Ask learners to write down where they lose their energy. A person runs out of energy when they don’t take enough energy from food (calories) but lose it all by heat to environment. In a closed system energy is conserved but we are not a closed system; we lose heat to the environment.
Learners find it difficult to distinguish the difference between energy and force. Learners can be provided with examples of energy e.g. car moving along a road has kinetic energy, and examples of force e.g. force is applied for the car to move. In pairs learners look at all the statements and decide what is the main difference between both pairs can then share their ideas with the class.
Learners find it difficult to understand the meaning of ‘work’ in scientific terms. In normal every day speak work may be something we do to earn money or work to study for an exam. Extra time may be needed when explaining work done and care needs to be taken about the language used. Work done could be explained as a job using a force, for example moving a car up hill, playing football, and lifting weights. Learners could be given many different situations and learners are to separate them as work done and work not done.
Conceptual links to other areas of the specification – useful ways to approach this topic to set students up for topics later in the course
The mathematical skills and understanding of key concepts of energy are useful for topics including ‘Power & efficiency’ (P5.2). P5.2 links strongly with conservation of energy (P5.1) and the amount of energy wasted.
The knowledge and understanding of ‘Work done’ builds on the work covered previously in sections P1.2 c,d,e (heat) and also P2.2 forces and P2.3 forces in action.
Approaches to teaching the content
Energy transformations occur all the time in everyday situations. Learners can be provided with the situation of making breakfast and must look into all the different energy transformations taking place: boiling a kettle, making toast using a toaster and you moving around making the breakfast.
Learners can look at dropping a ball from the top of a table or even at a building and look at the link between gravitational potential energy and kinetic energy. A situation like this paves the way for looking at their calculations and applying the equations.
OCR’s resources are provided to support the teaching of OCR specifications, but in no way constitute an endorsed teaching method that is required by the Board and the decision to use them lies with the individual teacher. Whilst every effort is made to ensure the accuracy of the content, OCR cannot be held responsible for any errors or omissions within these resources. We update our resources on a regular basis, so please check the OCR website to ensure you have the most up to date version.
© OCR 2016 - This resource may be freely copied and distributed, as long as the OCR logo and this message remain intact and OCR is acknowledged as the originator of this work.