G3 Physics and O-Level Kinematics Hub
Study G3 Physics and O-Level kinematics in order: motion quantities, acceleration, displacement–time and velocity–time graphs, free fall and practice.
Learning goals
- State what speed means
- State what velocity means, including its direction
- Calculate average speed from total distance and total time
- Calculate acceleration as change in velocity divided by time taken
- State what uniform acceleration means
- Interpret examples of non-uniform acceleration
- Plot and interpret displacement–time and velocity–time graphs in one dimension
- Deduce rest and uniform or non-uniform velocity from a displacement–time graph
- Deduce rest, uniform velocity and uniform or non-uniform acceleration from a velocity–time graph
- Use signed area under a velocity–time graph to determine displacement
- Recall constant free-fall acceleration near Earth as approximately 10 m/s²
Kinematics describes motion using quantities, graphs and equations. Follow the core route below before starting Dynamics.
Prerequisite: Scalars and vectors, because displacement and velocity include direction.
If this is your first pass, work through the Lessons below from top to bottom. The sequence moves from definitions to graph skills, then applies both to free fall.
Practice route: use the Kinematics Graph Explorer, complete the structured questions, then use the quiz to recheck weak definitions.
Lessons
Motion quantities
Distance and displacement
Separate total path length from signed change in position.
Speed and velocity
Calculate rates of change and keep vector direction clear.
Acceleration
Use change in velocity per unit time, including signs.
Core graph skills
Reading kinematics graphs
Interpret motion from shape, gradient and direction.
Plotting kinematics graphs
Choose scales and distinguish exact connections from best-fit trends.
Area under velocity–time graphs
Find displacement from signed area and distance from area magnitudes.
Free fall
Free fall and gravitational acceleration
Apply constant downward g when air resistance is negligible.
Free fall means gravity is the only force. Study Terminal Velocity separately for air resistance, changing resultant force and constant terminal speed.
Practical context
Ticker-tape timer
Find speed and acceleration from dot spacing, counting gaps rather than dots.
Beyond the syllabus
Equations of motion (SUVAT)
Solve constant-acceleration problems with the equations of uniformly accelerated motion.
Revision
Core graph meanings
| Graph feature | Physical meaning |
|---|---|
| gradient of displacement–time | velocity |
| gradient of velocity–time | acceleration |
| signed area under velocity–time | displacement |
| total area magnitudes under velocity–time | distance travelled |
Area under a displacement–time graph has no standard kinematics meaning.
High-value exam checks
- State a positive direction before a signed calculation.
- “From rest” means u = 0; “comes to rest” means v = 0.
- A negative velocity means motion in the negative direction, not negative speed.
- At the highest point of an upward throw, v = 0 but acceleration is still downwards.
- A horizontal velocity–time line means a = 0; it does not necessarily mean the object is at rest.
- Use a best-fit line for scattered experimental data, but connect exact consecutive motion data as instructed.
Check your understanding
Worked example: A cyclist travels 100 m east in 10 s, then 40 m west in 5.0 s. The total distance is 140 m, while the displacement is 60 m east. Therefore,
average speed = 140/15 = 9.3 m s⁻¹
and
average velocity = 60/15 = 4.0 m s⁻¹ east.
Practise this: Sketch a velocity–time graph for 4.0 m s⁻¹ east for 3.0 s followed by 2.0 m s⁻¹ west for 2.0 s. Use signed areas to find the displacement and area magnitudes to find the distance.
Practice
- Use the Kinematics check for distance, displacement, speed, velocity, acceleration, free fall and signed motion graphs.
- Complete the structured kinematics questions when you can explain the graph shapes without prompts.
Continue learning
Continue to Dynamics to connect changes in motion to resultant force.
Course and syllabus information
- Course
- SEC G3 Physics
- Edition
- SEC G3 Physics 2027