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MYP Physics: Distance-Time & Velocity-Time Graphs FAQ
Answered by RevisionPrep's IB Educators
Motion graphs trip up more MYP 4-5 students than almost any other Physics topic — not because the maths is hard, but because it's easy to mix up what a gradient means on each graph. Here's what you actually need to know, answered straight.
The core concept
Distance-time & velocity-time graphs: what do MYP Physics students need to know?
You need two things: on a distance-time graph, the gradient gives you speed (a straight line means constant speed, a curve means acceleration). On a velocity-time graph, the gradient gives acceleration, and the area under the graph gives distance travelled. Mix those two up and every answer after it falls apart.
Quick reference:
- Distance-time graph gradient = speed
- Distance-time flat line = object stationary
- Velocity-time graph gradient = acceleration
- Velocity-time area under line = distance travelled
- Velocity-time flat line = constant velocity, not stopped
This maps directly onto the MYP Sciences aim of interpreting graphical data (Criterion B: Inquiring and Designing, and Criterion A knowledge application), which is exactly why teachers hammer it in Year 4-5.
How do you find speed from a distance-time graph?
Speed is the gradient: divide the change in distance by the change in time between two points on the line. For a curved section, draw a tangent at that point and find the gradient of the tangent — that gives you the instantaneous speed at that exact moment, not the average.
Worked example: A cyclist covers 60 m in 12 seconds on a straight-line section of a distance-time graph.
Gradient = change in distance ÷ change in time = 60 ÷ 12 = 5 m/s.
If the line curves upward more steeply later, the cyclist is speeding up — draw a tangent at that later point and repeat the calculation for the instantaneous speed there.
How do you find acceleration from a velocity-time graph?
Acceleration is the gradient of the velocity-time graph: change in velocity divided by change in time. A positive gradient means speeding up, a negative gradient (sloping down) means slowing down, and a flat horizontal line means zero acceleration — the object's moving at constant speed.
Worked example: A car's velocity rises from 4 m/s to 16 m/s over 6 seconds.
Acceleration = (16 − 4) ÷ 6 = 12 ÷ 6 = 2 m/s².
Common mistake: students report this as 2 m/s, dropping the squared unit. Acceleration is always in m/s² — remember it's a rate of change of a rate.
How do you find distance from a velocity-time graph?
Distance is the area under the velocity-time graph, not the gradient — that's the single most common mix-up I see in mocks. For a straight-line section, split the shape into rectangles and triangles, calculate each area separately, then add them together.
Worked example: An object accelerates from 0 to 10 m/s over 5 seconds, then travels at a constant 10 m/s for a further 8 seconds.
- Triangle (acceleration phase): ½ × base × height = ½ × 5 × 10 = 25 m
- Rectangle (constant phase): base × height = 8 × 10 = 80 m
- Total distance = 25 + 80 = 105 m
Quick tip: sketch the shape first and label it triangle, rectangle or trapezium before reaching for a formula — it stops you guessing which calculation applies.
Common mistakes & exam technique
What's the difference between distance-time and velocity-time graphs?
A distance-time graph plots how far an object has travelled against time, and its gradient tells you speed. A velocity-time graph plots how fast the object is moving against time, and its gradient tells you acceleration while the area underneath tells you distance. Same axes shape, completely different information.
| Feature | Distance-time graph | Velocity-time graph |
|---|---|---|
| Y-axis | Distance | Velocity |
| Gradient means | Speed | Acceleration |
| Area under line means | Nothing meaningful | Distance travelled |
| Flat line means | Object stationary | Constant velocity |
| Curve means | Changing speed | Changing acceleration |
What mistakes do MYP students commonly make with motion graphs?
The biggest one: reading a flat line on a velocity-time graph as "stopped" — it actually means constant speed, not zero speed. The second biggest: trying to find distance from a velocity-time graph by measuring the gradient instead of the area underneath.
Three to check before your next mock:
- Did you check which graph you're on before touching the gradient — distance-time or velocity-time?
- For area calculations, did you split the shape into rectangles/triangles rather than guessing a formula?
- Did you include correct units — m/s for speed, m/s² for acceleration, m for distance — in every final answer?
A flat line on a distance-time graph does mean stationary. That's the one case where "flat = stopped" is actually correct, which is exactly why the two graphs get confused.
How are motion graphs assessed in MYP Physics?
Motion graphs sit under MYP Sciences Criterion A (Knowing and Understanding) and Criterion C (Processing and Evaluating), where you're expected to construct, interpret and draw conclusions from graphical data — not just plug numbers into a formula. Command terms like "describe," "determine" and "deduce" all appear regularly around this topic.
According to the MYP: Sciences guide, students at the higher achievement levels (7-8) are expected to interpret data with minimal guidance and identify trends independently — for motion graphs that means spotting acceleration patterns from a curve, not just reading a straight-line gradient off a ruler.
How do I sketch a velocity-time graph from a word description?
Break the description into phases — starting speed, any acceleration, any constant sections, any deceleration to a stop — and sketch each phase as a straight-line segment in order. Label your axes with units, mark key values on both axes, and check the shape matches each phase you identified.
Worked example: "A runner accelerates uniformly from rest to 8 m/s in 4 seconds, holds that speed for 6 seconds, then decelerates to a stop in 2 seconds."
- From (0,0) to (4,8) — straight line rising, this is the acceleration phase.
- From (4,8) to (10,8) — flat horizontal line, constant velocity.
- From (10,8) to (12,0) — straight line falling steeply back to zero.
The steepest section is the deceleration phase — it happens over the shortest time, so the gradient (and therefore the magnitude of acceleration) is largest there.
Getting a level 7 & exam prep
How do I get a high grade on MYP motion graph questions?
Show your working for every gradient and area calculation, always include correct units, and use full physics vocabulary — "the object is decelerating uniformly" scores far better than "it's slowing down." Examiners at the top achievement bands want interpretation, not just calculation.
Checklist for level 7-8 responses:
- State which graph you're reading and what the gradient/area represents before calculating
- Show the substitution step, not just the final number
- Include units at every stage, not just the final answer
- Use comparative language ("greater than," "constant," "uniformly") when describing trends
- Where a graph has multiple phases, address each phase separately rather than describing the whole graph in one sentence
What past-paper style questions should I practise for this topic?
Practise a mix: calculating gradients from given coordinate pairs, working out areas under multi-phase velocity-time graphs, sketching graphs from a written scenario, and converting between the two graph types for the same motion. These four question types cover almost everything MYP assessments ask.
On revisionprep.com you'll find Topical Worksheets built around exactly this mix, plus Mock Papers that combine motion graphs with force and momentum questions the way real MYP eAssessment-style tasks often do — useful once you're comfortable with the basics and want exam-condition practice.
Support & resources (for parents)
Why is my child struggling with motion graphs in MYP Physics?
Almost always it's the gradient-versus-area confusion between the two graph types, not a lack of maths ability — your child can usually do the arithmetic fine but hasn't nailed down which calculation applies to which graph. A bit of targeted practice distinguishing the two graphs clears this up quickly.
What helps at home: ask your child to explain out loud what a flat line means on each graph before they calculate anything. If they can say "stationary" for distance-time and "constant speed" for velocity-time without hesitating, the concept has actually landed — the calculations follow much more easily after that.
What resources help with MYP Physics motion graphs?
Look for resources with worked examples showing full gradient and area calculations step by step, not just definitions — that's where most textbooks fall short. Revision Notes paired with Topical Worksheets that isolate this one skill let your child practise repeatedly before mixing it with other Physics topics.
RevisionPrep's MYP Physics Revision Notes cover distance-time and velocity-time graphs with the worked calculations shown in full, and the accompanying Topical Worksheets are graded by difficulty — useful if you want your child building confidence before tackling combined-topic Mock Papers.
Distance-Time vs Velocity-Time Graphs
| Feature | Distance-time graph | Velocity-time graph |
| Y-axis | Distance | Velocity |
| Gradient means | Speed | Acceleration |
| Area under line means | Nothing meaningful | Distance travelled |
| Flat line means | Object stationary | Constant velocity |
For step-by-step worked examples and graded practice on this exact topic, see the MYP Physics Revision Notes and Topical Worksheets on revisionprep.com.