Equations of motion
Cambridge A-Level Physics (9702) · Unit 2: Kinematics · 10 flashcards
Equations of motion is topic 2.1 in the Cambridge A-Level Physics (9702) syllabus , positioned in Unit 2 — Kinematics . In one line: Displacement is the shortest distance from the initial to the final position, along with the direction. Distance is the total length of the path traveled. Displacement is a vector, while distance is a scalar.
Marked as AS Level: examined at AS Level in Paper 1 (Multiple Choice), Paper 2 (AS Structured Questions) and Paper 3 (Advanced Practical Skills). The same content may also be assumed in Paper 4 (A Level Structured Questions).
The deck below contains 10 flashcards — 5 definitions, 4 key concepts and 1 calculation — covering the precise wording mark schemes reward. Use the 5 definition cards to lock down command-word answers (define, state), then move on to the concept and calculation cards to handle explain, describe, calculate and compare questions.
Displacement and how it differs from distance
Displacement is the shortest distance from the initial to the final position, along with the direction. Distance is the total length of the path traveled. Displacement is a vector, while distance is a scalar.
What the Cambridge 9702 syllabus says
Official 2025-2027 spec · AS LevelThese are the exact learning outcomes Cambridge sets for this topic. The candidate is expected to be able to do each of these on the relevant paper.
- define and use distance, displacement, speed, velocity and acceleration
- use graphical methods to represent distance, displacement, speed, velocity and acceleration
- determine displacement from the area under a velocity–time graph
- determine velocity using the gradient of a displacement–time graph
- determine acceleration using the gradient of a velocity–time graph
- derive, from the definitions of velocity and acceleration, equations that represent uniformly accelerated motion in a straight line
- solve problems using equations that represent uniformly accelerated motion in a straight line, including the motion of bodies falling in a uniform gravitational field without air resistance
- describe an experiment to determine the acceleration of free fall using a falling object
- describe and explain motion due to a uniform velocity in one direction and a uniform acceleration in a perpendicular direction
- understand that mass is the property of an object that resists change in motion
- recall F = ma and solve problems using it, understanding that acceleration and resultant force are always in the same direction
- define and use linear momentum as the product of mass and velocity
- define and use force as rate of change of momentum
- state and apply each of Newton’s laws of motion
- describe and use the concept of weight as the effect of a gravitational field on a mass and recall that the weight of an object is equal to the product of its mass and the acceleration of free fall
- www.cambridgeinternational.org/alevel
Cambridge syllabus keywords to use in your answers
These are the official Cambridge 9702 terms tagged to this section. Mark schemes credit responses that use the exact term — weave them into your answers verbatim rather than paraphrasing.
Tips to avoid common mistakes in Equations of motion
- › Check the plane of motion; only use 'g' for vertical motion or components of motion on a slope, never for horizontal travel.
- › Always check the value of a single small grid square on both axes before calculating gradients or areas.
- › Always treat horizontal and vertical components independently; for a horizontally projected object, the initial vertical velocity (uy) is 0.
- › Recall that average velocity is displacement divided by time; if an object returns to its starting position, its displacement and average velocity are zero.
- › Analyze horizontal and vertical motion independently; for horizontal projectiles, the initial vertical velocity is always zero.
Define displacement and how it differs from distance.
Displacement is the shortest distance from the initial to the final position, along with the direction. Distance is the total length of the path traveled. Displacement is a vector, while distance is a scalar.
What is the definition of acceleration?
Acceleration is the rate of change of velocity with respect to time. It is a vector quantity, meaning it has both magnitude and direction. Mathematically, it's defined as a = Δv/Δt.
Describe how to determine displacement from a velocity-time graph.
The displacement is equal to the area under the velocity-time graph. If the velocity is negative at any point, that area below the x-axis is negative displacement.
How is velocity determined from a displacement-time graph?
The velocity at any point on a displacement-time graph is equal to the gradient (slope) of the graph at that point. The gradient indicates the rate of change of displacement with respect to time.
State the equations of uniformly accelerated motion in a straight line (SUVAT equations).
The SUVAT equations are: v = u + at, s = ut + (1/2)at², v² = u² + 2as, and s = (u+v)t/2, where s=displacement, u=initial velocity, v=final velocity, a=acceleration, and t=time.
Describe an experiment to determine the acceleration of free fall using a falling object and a trapdoor.
An electromagnet holds a steel ball. When the current is cut, the ball is released and a timer starts. The ball falls a measured distance (s) and hits a trapdoor, stopping the timer. Using s = ut + (1/2)gt² (u=0), g ≈ 2s/t² is calculated.
Explain how the horizontal and vertical components of projectile motion are treated separately.
In projectile motion, the horizontal component of velocity is constant (assuming no air resistance) as there's no horizontal acceleration. The vertical component is affected by gravity (constant downward acceleration 'g'). These are analyzed independently and then combined to describe the overall motion.
State Newton's First Law of Motion.
An object at rest stays at rest and an object in motion stays in motion with the same speed and in the same direction unless acted upon by a net force.
Define linear momentum and its SI unit.
Linear momentum (p) is the product of an object's mass (m) and its velocity (v): p = mv. Its SI unit is kg m/s.
State Newton's Second Law of Motion in terms of momentum.
Newton's Second Law states that the resultant force acting on an object is equal to the rate of change of its momentum: F = Δp/Δt.
Review the material
Read full revision notes on Equations of motion — definitions, equations, common mistakes, and exam tips.
Read NotesKey terms covered in this Equations of motion deck
Every term below is defined in the flashcards above. Use the list as a quick recall test before your exam — if you can't define one of these in your own words, flip back to that card.
How to study this Equations of motion deck
Start in Study Mode, attempt each card before flipping, then rate Hard, Okay or Easy. Cards you rate Hard come back within a day; cards you rate Easy push out to weeks. Your progress is saved in your browser, so come back daily for 5–10 minute reviews until every card reads Mastered.
Study Mode
Rate each card Hard, Okay, or Easy after flipping.