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 state Newton’s first law in rotational form and explain why a system spinning at a steady rate is in rotational equilibrium. (Guide: “Newton’s first law in rotational form”; Practice Q1)
- I can state the corollary: if the torques are unbalanced, the angular velocity must be changing. (Guide: “Newton’s first law in rotational form”)
- I can explain, with a couple and a tumbling object as examples, why rotational and translational equilibrium are independent. (Guide: “Equilibrium of one kind only”; Practice Q7)
Calculation
- I can draw an extended force diagram that shows where each force acts, including the weight at the center of mass. (Guide: Figures 1 and 2; Practice Q4)
- I can show by integration that a distributed weight has torque Mg x_cm about a pivot. (Guide: “Extended force diagrams”)
- I can find the mass and center of mass of a rod with a given λ(x) and use them to find support forces. (Guide: Worked example 1; Practice Q3, Q5)
- I can use ΣF = 0 and Στ = 0 together to find a cable tension and the size and direction of a hinge force. (Practice Q4)
- I can find the condition for an object to be about to tip, using the fact that one support force falls to zero. (Guide: Worked example 1(b))
Reasoning
- I can derive τ_Q = τ_P − d × ΣF and use it to justify choosing any torque point when ΣF = 0. (Guide: “Choosing the point for torques”; Practice Q2)
- I can recognise a statically indeterminate problem and say which forces can and cannot be found. (Guide: Worked example 2(c))
- I can predict how a support force changes when a distance changes, and linearise data to extract a mass. (Guide: Worked example 2; Practice Q6)
All ticked? Move on to Topic 5.6, Newton’s Second Law in Rotational Form, or return to the course roadmap.