TCE Physics — Level 4
Newton's Laws — Flashcards & Quiz
Newton's three laws of motion are the foundation of classical mechanics, and TCE Physics Level 4 expects you to apply them to free-body diagrams, solve net force problems, and explain action-reaction pairs. The second law F = ma is your go-to equation for any force/acceleration calculation.
Key Points
- First Law (Inertia): an object in motion stays in motion (and at rest stays at rest) unless acted on by an external force.
- Second Law: F_net = ma. The acceleration of an object is proportional to the net force and inversely proportional to its mass.
- Third Law: for every action there is an equal and opposite reaction. Action-reaction pairs act on different objects.
- Free-body diagrams show all forces acting on a single object: weight, normal, friction, tension, applied force, air resistance.
- On an incline, resolve weight into components: mg sinθ parallel to slope (down the slope), mg cosθ perpendicular (into slope).
- Friction opposes relative motion: kinetic friction f = μ_k N (constant); static friction f ≤ μ_s N (adjusts up to maximum).
Common Mistakes to Avoid
- Confusing mass (scalar, kg) with weight (force, N) — weight is mg, where g = 9.8 m/s².
- Drawing action-reaction pairs on the same object — they act on DIFFERENT objects.
- Forgetting to resolve forces into components on an inclined plane.
- Using F = ma without identifying the NET force first.
- Mixing up kinetic friction (sliding, constant μ_k) with static friction (not yet moving, up to μ_s).
Exam Strategy
TASC Level 4 Newton's laws questions give you a scenario and ask you to find forces, acceleration, or direction of motion. Method: (1) draw a free-body diagram with all forces labelled, (2) choose axes (usually along and perpendicular to motion), (3) resolve forces into components, (4) apply F_net = ma in each direction, (5) solve for unknowns.
Sample Flashcards
Q1: State Newton's First Law of Motion.
An object remains at rest or in uniform motion in a straight line unless acted upon by a net external force. This is the law of inertia.
Q2: State Newton's Second Law and its mathematical form.
The net force on an object equals its mass times its acceleration: F_net = ma. The direction of acceleration is the same as the direction of the net force.
Q3: State Newton's Third Law and give an example.
For every action force there is an equal and opposite reaction force. The two forces act on different objects, are the same type, and exist simultaneously.
Q4: Explain the concept of inertia and its relationship to mass.
Inertia is the resistance of an object to changes in its state of motion. Mass is the quantitative measure of inertia — greater mass means greater resistance to acceleration.
Sample Quiz Questions
Q1: An object at rest will remain at rest unless acted upon by a net external force.
Answer: TRUE
This is Newton's First Law (law of inertia). Without a net force, the state of motion does not change.
Q2: Newton's Third Law action-reaction pairs act on the same object.
Answer: FALSE
Third-law pairs always act on DIFFERENT objects. E.g. Earth pulls you down, you pull Earth up.
Q3: Doubling the net force on an object doubles its acceleration (mass constant).
Answer: TRUE
From F = ma, if m is constant then a is directly proportional to F.
Revision Tip
Free-body diagrams are the foundation — drill a Revizi deck with 8+ scenarios (horizontal motion, inclined plane, pulley systems, hanging mass) until diagram construction is automatic.
Last updated: March 2026 · 4 flashcards · 4 quiz questions