Moments, Pressure & Hooke's Law
CONCEPTUALCalculate the turning effect (moment = force × perpendicular distance), explain how pressure is transmitted equally in liquids (Pascal's principle) and the concept of atmospheric pressure, and describe Hooke's Law (extension ∝ force up to the elastic limit)
Mastery Evidence
- Calculates the moment of a force and uses the principle of moments to solve lever problems
- Explains why hydraulic systems can multiply force (pressure transmitted equally)
- States Hooke's Law and plots force-extension graphs identifying the elastic limit
- Calculates spring constant k from a force-extension graph (k = F/x)
Assessment Prompt
“If [child] was using a long spanner to loosen a tight bolt, could they explain why a longer spanner makes it easier — and work out what force would be needed with a spanner of a specific length?”
Curriculum Standards3 alignments
MS-PS2-2Next Generation Science Standards (NGSS) Middle Schoolcodes onlyKS3.Sci.Phys.MotionAndForces.6The national curriculum in Englandthe turning effect of forces; pressure in liquids transmitting pressure equally in all directions; atmospheric pressure
KS3.Sci.Phys.MotionAndForces.9The national curriculum in Englandelastic potential energy stored in a spring; the elastic limit; Hooke's Law; restoring force
Prerequisites2
- Resultant ForcessoftAges 11—12
- Levers, Pulleys & GearshardAges 9—10
Show full prerequisite tree
- Resultant Forces soft
Moments and pressure are applications of force — understanding forces as vectors and resultant forces provides the foundation
- Pushes & Pulls hard
KS3 forces as vectors extends KS2 introduction to pushes and pulls changing speed and direction
- Drawing Force Diagrams soft
Understanding pushes and pulls as forces is supported by the arrow representation of magnitude and direction
- Force & Motion Vocabulary hard
Describing balanced and unbalanced forces as vector quantities requires resultant force, balanced forces vocabulary
- Drawing Force Diagrams hard
Forces as vectors with magnitude and direction is the formal underpinning of the force arrow representation
- Contact & Non-Contact Forces hard
KS3 resultant force and balanced forces extends KS2 distinction between contact and non-contact forces
- 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
- Levers, Pulleys & Gears hard
KS3 moments and mechanical advantage extends KS2 introduction to levers, pulleys and gears allowing smaller force for greater effect
- Balanced & Unbalanced Forces hard
Must understand forces and their effects before learning how mechanisms multiply 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
- Gravity & Falling Objects soft
Gravity context helps understand why we need mechanisms to lift heavy things
- Balanced & Unbalanced Forces soft
Balanced/unbalanced forces supports understanding gravity as an unbalanced force on unsupported objects
- 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
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
- 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
- Force & Motion Vocabulary soft
Understanding levers, pulleys, and gears requires moment, lever, and fulcrum vocabulary
Unlocks1
- Investigating ForceshardAges 12—13