Work through the list without notes. If you cannot do a statement, follow its link, then come back. Guide = study guide; Practice = practice questions.
Understanding
- I can explain power as the rate of energy transfer into or out of a system, or of conversion inside it, and say which applies once I have chosen the system. (Guide: “Power is a rate”; Practice Q4)
- I can explain the difference between energy and power, and why a kilowatt-hour is an energy unit. (Guide: “Average power”; Practice Q1)
- I can explain why a force at right angles to the velocity has zero power and a force against the velocity has negative power. (Guide: “Instantaneous power”; Worked example 2)
Skills
- I can calculate average power from an energy change or from the work done, with time in seconds. (Guide: Worked example 1; Practice Q1, Q4)
- I can use P = Fv cos θ with only the force component along the velocity. (Guide: Worked example 2; Practice Q2)
- I can find power from the slope of an energy–time graph and energy from the area under a power–time graph. (Guide: Figures 1 and 2; Practice Q3)
- I can find the top speed of a vehicle, or its speed on a hill, from its power and the forces it must balance. (Guide: “Why a vehicle has a top speed”; Practice Q5)
- I can plan a power measurement, process the data and choose a graph with sensible axes and scales. (Guide: “Measuring power in the lab”; Practice Q6)
Reasoning
- I can derive P = F∥v from the definition of work and use it to explain why constant force can give rising power. (Guide: Worked example 3; Practice Q7)
- I can derive a symbolic expression for average power and predict how it changes when one quantity changes. (Practice Q7)
- I can account for every watt of input power by tracking where the energy goes. (Guide: Worked example 2; Practice Q4, Q5)
- I can use experimental data to support or challenge a claim about power, quoting values as evidence. (Practice Q6)
All ticked? Move on to Topic 4.1, Linear Momentum, or return to the course roadmap.