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 centres, and acting at each centre of mass. (Guide: Figure 1)
- I can explain why the forces two bodies exert on each other are equal, even when one is far more massive. (Guide: “Gravity is an interaction between masses”; Practice Q4)
- I can explain what a gravitational field is and why N/kg is the same unit as m/s². (Guide: “The gravitational field”)
- I can explain when the gravitational force near a planet can be treated as constant, and when it cannot. (Guide: “Weight, and when gravity is constant”)
- I can tell inertial mass from gravitational mass and explain why their equality makes all objects fall with the same acceleration. (Guide: “Inertial mass and gravitational mass”; Practice Q7)
Skills
- I can calculate a gravitational force with G, both masses and the centre-to-centre distance. (Guide: Worked example 1; Practice Q4)
- I can predict the factor of change in force or field strength when masses and distances change. (Guide: inverse-square table, Worked example 2; Practice Q1, Q2)
- I can calculate g at a height above a planet by adding the height to the radius. (Guide: Worked example 2; Practice Q7)
- I can calculate apparent weight in an accelerating lift with F_N = m(g + a_y). (Guide: Worked example 3; Practice Q5)
- I can linearise field-strength data by plotting g against 1/r² and find the central mass from the slope. (Practice Q6)
Reasoning
- I can explain why a scale reading depends on the lift’s acceleration and not on its velocity. (Guide: Figure 3; Practice Q3, Q5)
- I can explain why astronauts in orbit appear weightless even though gravity acts on them. (Guide: “Weightlessness and the equivalence principle”; Practice Q7)
- I can state the equivalence principle in my own words, using a closed lift as the example. (Guide: “Weightlessness and the equivalence principle”)
All ticked? Move on to Topic 2.7, Kinetic and Static Friction, or return to the course roadmap.