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Universal Gravitation

CONCEPTUAL
Science›Space Systems & Earth's History|Ages 12—13|ID: mt_oLjz18CxDg

Describe gravity as a universal attractive force between all masses, explain that orbital motion arises because gravity provides the centripetal force keeping objects in orbit, and compare gravitational field strengths on different planets

Mastery Evidence

  • States that gravity is a universal attractive force acting between all objects with mass
  • Explains that orbital motion occurs because gravity continuously deflects the path of the orbiting object
  • Compares gravitational field strength on different planets and explains how this affects weight

Assessment Prompt

“If [child] was asked why the Moon doesn't fly off into space but also doesn't crash into Earth, could they explain that gravity is constantly pulling it into a curved path — like swinging a ball on a string?”

Curriculum Standards2 alignments

MS-ESS1-2Next Generation Science Standards (NGSS) Middle Schoolcodes only
Standard code — full text not included in this dataset.
KS3.Sci.Phys.SpacePhysics.4The national curriculum in England
The Solar System

the Sun, Earth and Moon as approximately spherical bodies; the relative sizes and distances of the Sun, Earth, Moon and solar system

Science · KS3

Prerequisites2

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  • The solar system (age 11+) hard

    Explaining orbital motion as gravity-driven centripetal force requires knowing what is in orbit (planets, moons) from the solar system topic

    • The solar system hard

      Detailed solar system structure (moons, asteroids, comets, orbital periods) extends KS2 overview of planets orbiting the Sun

      • Naming the Planets hard

        Describing sun, Earth, and moon as spherical bodies and planets orbiting the sun requires solar system vocabulary

      • Sun, Moon, and stars hard

        Must observe sun/moon patterns before learning about the solar system model

        • Naming the Planets hard

          Describing predictable patterns of sun, moon, and stars requires planet, star, moon, orbit vocabulary

        • Why seasons change hard

          Must observe sun/moon/star patterns before relating daylight to time of year

          • Naming the Planets soft

            Relating daylight length to time of year draws on orbit and solar system vocabulary

          • Seasonal changes soft

            Seasonal changes observation supports daylight pattern recognition

    • Naming the Planets hard

      Describing the detailed solar system structure including moons, asteroids, and comets requires all this vocabulary

  • Mass vs Weight hard

    Universal gravity and orbital mechanics build directly on mass vs weight and the concept that gravitational field strength varies between planets

    • Gravity & Falling Objects hard

      KS3 weight = mass × g extends KS2 introduction to gravity as the force pulling objects toward Earth

      • Balanced & Unbalanced Forces soft

        Balanced/unbalanced forces supports understanding gravity as an unbalanced force on unsupported objects

        • Pushes & Pulls hard

          Must understand pushes/pulls before investigating balanced vs unbalanced forces

          • Drawing Force Diagrams soft

            Understanding pushes and pulls as forces is supported by the arrow representation of magnitude and direction

        • Drawing Force Diagrams hard

          Investigating balanced and unbalanced forces requires drawing force diagrams to record and analyse experimental findings

        • Friction & Surfaces hard

          Must understand friction affects motion before investigating balanced/unbalanced forces

          • Pushes & Pulls hard

            Must understand forces change motion before comparing movement on different surfaces

            • Drawing Force Diagrams soft

              Understanding pushes and pulls as forces is supported by the arrow representation of magnitude and direction

          • Forces Vocabulary hard

            Comparing how things move on different surfaces requires friction vocabulary

      • Forces Vocabulary hard

        Explaining gravity requires the force vocabulary: gravity, weight, non-contact force

      • Drawing Force Diagrams hard

        Explaining gravity as a downward force requires representing it as a downward arrow in a force diagram

      • Contact & Non-Contact Forces hard

        Must know about non-contact forces before learning gravity as a non-contact force

        • Forces Vocabulary hard

          Distinguishing contact from non-contact forces requires these exact terms

        • Drawing Force Diagrams soft

          Distinguishing contact and non-contact forces is clarified by drawing force diagrams showing where arrows originate

        • Friction & Surfaces hard

          Must experience contact forces like friction before distinguishing contact vs non-contact forces

          • Pushes & Pulls hard

            Must understand forces change motion before comparing movement on different surfaces

            • Drawing Force Diagrams soft

              Understanding pushes and pulls as forces is supported by the arrow representation of magnitude and direction

          • Forces Vocabulary hard

            Comparing how things move on different surfaces requires friction vocabulary

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