IGCSE Physics: Motion Practice Questions
Speed is distance travelled per unit time and acceleration is the change in velocity per unit time. On a distance-time graph the gradient gives speed, and on a speed-time graph the gradient gives acceleration while the area under the line gives distance travelled.
Sub-topic 1.2 of Cambridge IGCSE Physics 0625 is dominated by graph work, and the single most valuable fact in the topic is that the area under a speed-time graph is the distance travelled. The questions below cover the calculations, both graph types and terminal velocity.
What you need to know for Motion
- Speed and velocitySpeed = distance divided by time and is a scalar. Velocity is speed in a stated direction and is a vector.
- AccelerationAcceleration = change in velocity divided by time taken, measured in m/s2. A negative acceleration means the object is slowing down.
- Distance-time graphA horizontal line means the object is stationary. A straight sloping line means constant speed, and the gradient gives that speed. A curve means the speed is changing.
- Speed-time graphThe gradient gives the acceleration. A horizontal line means constant speed. The area under the line gives the distance travelled.
- Acceleration of free fallNear the Earth's surface all objects accelerate downwards at approximately 9.8 m/s2 when air resistance can be ignored, regardless of their mass.
- Terminal velocityAs a falling object speeds up, air resistance increases. When air resistance equals weight the resultant force is zero, so acceleration stops and the object falls at a constant speed.
IGCSE Physics Motion questions and answers
4 exam-style questions written to the 0625 syllabus. Try each one on paper first, then open the worked answer to check your method against the marks.
A car increases its velocity from 8.0 m/s to 26 m/s in 6.0 s. Calculate its acceleration.
Show the worked answer
- Use acceleration = change in velocity divided by time taken.
- Change in velocity = 26 minus 8.0 = 18 m/s.
- Acceleration = 18 divided by 6.0.
- Acceleration = 3.0 m/s2.
A speed-time graph shows a cyclist accelerating uniformly from rest to 12 m/s over 8.0 s, then travelling at 12 m/s for a further 20 s. Calculate the total distance travelled.
Show the worked answer
- The distance travelled is the area under the speed-time graph.
- The first section is a triangle: area = half x base x height = 0.5 x 8.0 x 12 = 48 m.
- The second section is a rectangle: area = 20 x 12 = 240 m.
- Total distance = 48 + 240 = 288 m.
A skydiver jumps from a stationary balloon and eventually falls at a constant speed before opening the parachute. Explain, in terms of forces, why she accelerates at first and then reaches a constant speed.
Show the worked answer
- At the moment she jumps, her speed is zero, so air resistance is zero and the only significant force is her weight acting downwards.
- There is a large resultant downward force, so she accelerates.
- As her speed increases, air resistance increases because she collides with more air particles per second.
- The resultant downward force therefore decreases, so her acceleration decreases even though she continues to speed up.
- Eventually air resistance equals her weight. The resultant force is zero, so by Newton's first law there is no further acceleration and she falls at a constant speed, her terminal velocity.
A distance-time graph for a runner shows a straight sloping line from the origin, then a horizontal line, then a steeper straight sloping line. Describe the motion in each of the three sections.
Show the worked answer
- Section 1: a straight sloping line means distance increases at a steady rate, so the runner moves at a constant speed. The speed is the gradient of that line.
- Section 2: a horizontal line means the distance is not changing, so the runner is stationary.
- Section 3: a straight sloping line again means constant speed.
- The third line is steeper than the first, so its gradient is larger and the runner is moving at a greater constant speed than in section 1.
Common mistakes in this topic
- Confusing distance-time graphs with speed-time graphs. A horizontal line means stationary on one and constant speed on the other.
- Forgetting that the area under a speed-time graph gives distance.
- Using final velocity instead of change in velocity in acceleration calculations.
- Saying an object at terminal velocity has stopped.
- Omitting units, particularly the squared in m/s2.
Exam tips
- Label which type of graph you are reading before you interpret it. Most errors in this topic come from mixing the two up.
- For area under a graph, split the shape into triangles and rectangles and add them.
- Write the equation, the substitution and the answer with a unit on separate lines to secure method marks.
- In terminal velocity questions, describe the forces at three stages: at the start, while speeding up, and at constant speed.
- Remember that all objects fall at the same rate when air resistance is negligible, regardless of mass.
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Motion FAQs
What does the area under a speed-time graph represent?
The area under a speed-time graph gives the distance travelled. Split the area into triangles and rectangles, calculate each and add them. The gradient of the same graph gives the acceleration, so a single speed-time graph provides both quantities.
What is terminal velocity?
Terminal velocity is the constant speed reached by a falling object when air resistance has increased until it equals the object's weight. The resultant force is then zero, so there is no further acceleration and the object continues to fall at a steady speed.
What is the difference between speed and velocity?
Speed is the distance travelled per unit time and is a scalar, so it has magnitude only. Velocity is speed in a stated direction and is a vector. An object moving in a circle at a steady rate has constant speed but changing velocity, because its direction keeps changing.
How do I calculate acceleration?
Divide the change in velocity by the time taken. Subtract the initial velocity from the final velocity first, then divide by the time. The unit is metres per second squared. A negative answer means the object is decelerating.
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Written to the published Cambridge IGCSE Physics (0625) syllabus. Check your school entry code and syllabus year, because Core and Extended candidates are assessed on different content. Last reviewed 2026-08-12.