MYP Physics: Newton's Laws of Motion FAQ

Students struggle because Newton's laws sound like common sense but use precise vocabulary — force, net force, inertia — in ways that contradict gut instinct. MYP Criterion A and D questions expect you to explain why an object needs a net force to change motion, not just state the law. That intuition-versus-definition gap trips up most learners.

Newton's first law: an object stays at rest or moves at constant velocity unless a net force acts on it (inertia). The second law: net force equals mass times acceleration, $F=ma$. The third law: every force has an equal, opposite reaction force acting on a different object.

Mass measures how much matter an object contains and stays constant everywhere, measured in kilograms. Weight is the gravitational force acting on that mass, measured in newtons, and changes depending on gravitational field strength. On the Moon your mass stays the same, but your weight drops to roughly a sixth of its Earth value.

The book stays still because the forces acting on it are balanced, not because no forces exist. Gravity pulls it down; the table's normal reaction force pushes up with equal size. Since the net force is zero, Newton's first law says the book keeps its state of rest — that's equilibrium, not an absence of force.

A level 7 answer names the correct law, states the relevant equation, and explains the physical reasoning using command terms like "explain" or "justify" — not just a calculated number. Examiners marking against Criterion A and D reward students who connect their answer to a real scenario and comment on whether the result is reasonable.

Work through past unit tests and topical worksheets rather than re-reading notes — Newton's laws are a doing topic, not a memorising one. Practise labelling all the forces on a diagram, then check each answer against the criterion descriptors your teacher marks against, since MYP rewards explanation over the final number alone.

The biggest mistake is pairing the wrong forces — students often pair an object's weight with the table's normal force, but the true third-law pair acts on two different objects entirely (the book pulls the Earth up exactly as the Earth pulls the book down). Action-reaction pairs never act on the same object.

Newton's laws are tested under Criterion A (Knowing and Understanding) for definitions and calculations, Criterion B when you design an experiment to test F=ma, Criterion C when you process force-and-acceleration data, and Criterion D when you evaluate real-world impacts such as seatbelt design. Most schools weight Criterion A heaviest for this topic.

Yes — Newton's laws sit within the "forces and energy" content strand of the MYP on-screen Sciences examination, mixing short calculations with extended-response items that require explanation. The IB's MYP eAssessment framework draws on content taught across MYP years 4 and 5, so Newton's laws are fair game regardless of which year your school covers them.

You need $F=ma$ (Newton's second law) and $W=mg$ (weight from mass and gravitational field strength). Newton's third law needs no formula — just the understanding that forces occur in equal, opposite pairs on different objects. MYP doesn't provide a formula booklet, so these must be memorised exactly.

MYP Physics introduces Newton's laws conceptually, with simple F=ma calculations and qualitative explanations. DP Physics extends the same laws into the "Forces" topic with vector force diagrams, connected systems of objects, and circular motion dynamics at SL and HL. According to the IB, the current DP Physics guide had first exams in 2025, and it demands considerably more mathematical rigour than MYP.

Neither is inherently harder — they cover similar core ideas around forces and F=ma but assess them differently. IGCSE Physics leans on exam-style calculation questions with a formula sheet provided, while MYP Physics assesses the same content through criterion-based tasks demanding explanation and inquiry design, which some students find harder to structure than to calculate.

Look for resources that pair clear explanations with practice questions marked against MYP criteria, not generic physics worksheets aimed at a different curriculum. On RevisionPrep, MYP Physics revision notes break Newton's laws into the same command-term language your child's teacher uses, alongside topical worksheets to build calculation confidence before assessments.