3.3 Forces: How do forces interact with objects?
Identify forces, resolve resultants and apply Newton's laws to motion and terminal speed.
How to study WJEC GCSE The Sciences
Move from a scientific model to a prediction or method, collect or interpret evidence, show quantitative working and finish with a conclusion whose limits match the data.
Core concepts
Concept 1
Distinguish mass, weight and other common contact or non-contact forces.
Exam cue: Identify the unit, entered tier, supplied reference material, command word and relevant scientific enquiry skill.
Concept 2
Draw force diagrams and calculate resultant force.
Exam cue: Draw all forces on the same object, set a sign convention and use the resultant rather than a single force.
Concept 3
Apply Newton's laws to acceleration, interactions and terminal motion.
Exam cue: Use scientific terminology, show quantitative working with units, and connect conclusions to data and the stated model.
Concept 4
Official subtopics: 3.3.1 Common forces; 3.3.2 Force diagrams and calculating resultant force; 3.3.3 Newton's laws; 3.3.4 Terminal speed.
Concept 5
Scientific enquiry and mathematical skills apply in this topic; bold amplification is Higher Tier only.
Risk pitfalls and guardrails
Treating balanced forces as meaning the object must be stationary.
Guardrail: Do not import outgoing 3430QD content, another science route, a fixed required-practical list or unsupported tier and connection assumptions.
Recalling a fact without applying it to the observation, data, practical method or unfamiliar context.
Guardrail: Use the live secure pack: Task A may use groups of up to three; Task B is individual and highly controlled. Two enquiries are selected by the centre from three.
Importing content, required practicals, tier rules or paper structure from the outgoing WJEC or another awarding-body route.
Guardrail: Bold amplification is Higher-only. Units 1-6 may mix tiers, but Unit 7 is untiered.
Memory anchors
Weight
The gravitational force on a mass.
Resultant force
The single force with the same effect as all forces combined.
Inertia
The tendency to resist a change in velocity.
Newton's third law
Interacting bodies exert equal and opposite forces on one another.
Terminal speed
Constant speed reached when resistive force balances driving force or weight.
Checkpoint rule
Do the check-up only after you can summarize each concept in one sentence and identify one dangerous pitfall from memory.
Knowledge Check (after reading)
Short check-up to confirm understanding of this module.
Check-up Questions
Which quantity is a vector? Identify the interacting bodies and resultant force before applying Newton's laws. Keep observations separate from scientific inferences.
A 12 N force acts east and a 7 N force acts west. What is the resultant? Identify the interacting bodies and resultant force before applying Newton's laws. Choose the option that remains valid across the stated range.
Answer all questions to submit.
Next step personalized recommendations
Continue learning
Move forward only after this module is stable.
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