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 describe the gravitational force between two masses: attractive, along the line of centers, acting at each center of mass, and equal in size on both. (Guide: “Newton’s law of universal gravitation”; Practice Q4(b))
- I can explain what a gravitational field is and why, with gravity as the only force, the acceleration equals g. (Guide: “The gravitational field”; Practice Q6(a))
- I can explain apparent weight as the normal force, and say when a system appears weightless. (Guide: “Apparent weight and weightlessness”; Practice Q2, Q7(b))
- I can state the equivalence principle and the difference between inertial and gravitational mass. (Guide: “Apparent weight and weightlessness” and “Inertial mass and gravitational mass”; Practice Q7(c))
Calculation
- I can predict the factor by which F_g or g changes when masses, distance or a planet’s radius change. (Guide: “The gravitational field”; Practice Q1)
- I can find g at a height above a planet and decide whether g can be treated as constant. (Guide: Worked example 1; Practice Q7(a))
- I can find a scale reading from N = m(g + a_y), including when a_y comes from differentiating v_y(t). (Guide: Worked example 2)
- I can find where the fields of two masses cancel. (Practice Q4(c))
- I can use partial mass to find the field inside a uniform sphere, and the shell theorem for a thin shell. (Guide: Worked example 3; Practice Q3)
Reasoning
- I can derive F = (GMm/R³)r inside a uniform sphere and sketch g against r inside and outside a sphere and a shell. (Guide: Figure 1; Practice Q5)
- I can find a planet’s field and mass from free-fall data by choosing a straight-line graph. (Practice Q6)
All ticked? Move on to Topic 2.7, Kinetic and Static Friction, or return to the course roadmap.