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 why a wheel spinning on a fixed axle has kinetic energy even though its centre of mass is at rest. (Guide: “A spinning wheel has kinetic energy”; Worked example 3)
- I can show, by adding ½mv² for each piece with v = rω, that the kinetic energy of a rotating rigid system is ½Iω². (Guide: “From ½mv² to ½Iω²”; Practice Q4)
- I can explain why mass far from the axis carries more kinetic energy than the same mass near it. (Guide: Figure 1; Practice Q2, Q4)
- I can explain why rotational kinetic energy is a scalar that is never negative, and add the energies of objects spinning in opposite directions. (Guide: “Rotational kinetic energy is a scalar”; Practice Q3)
Calculation
- I can calculate rotational kinetic energy for a few point objects, or for an object with a given rotational inertia. (Guide: Worked example 1; Practice Q4)
- I can convert rev/min to rad/s before using K = ½Iω². (Guide: “Units: always rad/s”; Practice Q5)
- I can find the total kinetic energy of an object that moves and spins as ½Mv_cm² + ½I_cm ω², and show it on an energy bar chart. (Guide: Worked example 2, Figure 2)
- I can predict the factor by which K changes when ω or I changes, including hoop against disc. (Guide: factors-of-change table; Practice Q1, Q2, Q5)
Reasoning
- I can find the kinetic energy of an object on a pivot either from ½I_pivot ω² or from ½Mv_cm² + ½I_cm ω², and explain why mixing the two double counts. (Guide: Worked example 1; Practice Q6)
- I can choose a graph of spin data that should be a straight line, find I from its slope, and use the data to support or refute a claim about K and ω. (Practice Q7)
All ticked? Move on to Topic 6.2, Torque and Work, or return to the course roadmap.