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Mass vs Weight

CONCEPTUAL
Science›Forces & Motion|Ages 11—12|ID: mt_sUVeVXzRuq

Distinguish between mass (amount of matter, measured in kg) and weight (gravitational force, measured in N), use the equation weight = mass × gravitational field strength, and explain why g differs on other planets and stars

Mastery Evidence

  • Explains the difference between mass and weight with correct units for each
  • Calculates weight using W = mg with g = 10 N/kg on Earth
  • Predicts what would happen to an object's weight on the Moon or Jupiter
  • Explains why mass stays constant but weight changes in different gravitational fields

Assessment Prompt

“If [child] weighed themselves on bathroom scales and was then asked what they would weigh on the Moon, could they explain the difference between mass and weight and work out a rough answer?”

Curriculum Standards2 alignments

MS-PS2-4Next Generation Science Standards (NGSS) Middle Schoolcodes only
Standard code — full text not included in this dataset.
KS3.Sci.Phys.MotionAndForces.10The national curriculum in England
Gravity, Weight and Mass

gravity force, weight = mass × gravitational field strength (g), on Earth g = 10 N/kg, different on other planets and stars

Science · KS3

Prerequisites1

Show full prerequisite tree
  • 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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