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 find the total angular momentum of a system by adding its parts about one axis, with signs. (Guide: “Total angular momentum of a system”; Practice Q7(b))
- I can explain that angular momentum is conserved in every interaction, and that a system’s L changes only by transfer to or from its surroundings. (Guide: “Choosing the system”; Practice Q6(e))
- I can choose a system whose angular momentum is constant, and explain why a force through the axis exerts no torque about it. (Guide: Worked example 2(a); Practice Q2, Q4(a))
Calculation
- I can use L_i = L_f to find a common angular velocity after two parts lock together, and find the kinetic energy lost. (Guide: Worked example 1)
- I can find the angular speed after a point object strikes and sticks to a pivoted body. (Practice Q2)
- I can write I as a function of time or position and find ω and dω/dt by calculus. (Guide: Worked example 2; Practice Q4)
- I can use an external angular impulse to find how long a system takes to stop. (Guide: Worked example 1(d))
Reasoning
- I can prove from Newton’s third law that internal torques cancel and give equal and opposite angular impulses. (Guide: “Why internal torques cancel”; Practice Q5)
- I can sketch L–t graphs for the parts and the whole of a system during an interaction. (Guide: Figure 1; Practice Q5(d))
- I can predict the changes in ω and K when a system changes shape, and say where the energy comes from. (Guide: “Changing shape”; Practice Q1, Q6(d))
- I can linearise rotating-platform data to test conservation and extract I and L. (Practice Q6)
- I can explain why parts of a system starting from rest can turn without the total L changing. (Practice Q3, Q7)
All ticked? Move on to Topic 6.5, Rolling, or return to the course roadmap.