IGCSE Physics Motion Questions and Worked Solutions
50 topic-wise practice questions on Motion (Unit 1: Motion, Forces and Energy), written to the Cambridge IGCSE Physics 0625 syllabus for 2026–2028, each with a step-by-step worked solution.
Topic guide: Motion
This topic describes how objects move. Speed is distance travelled per unit time, velocity adds direction, and acceleration is the rate of change of velocity. Distance–time and speed–time graphs show motion visually: gradients and areas carry meaning.
Key formulas
| v = s ÷ t | speed v (m/s), distance s (m), time t (s) | Core |
| average speed = total distance ÷ total time | include stationary time in total time | Core |
| a = Δv ÷ Δt | acceleration a (m/s²), change in velocity Δv (m/s), time Δt (s) | Extended |
| distance = area under speed–time graph | triangles, rectangles, trapezia | Core |
| g ≈ 9.8 m/s² | acceleration of free fall near the Earth's surface | Core |
Prerequisite knowledge
- Rearranging simple equations
- Area of a triangle and a rectangle
- Plotting and reading graphs; finding a gradient
Exam tips & common mistakes
- Convert km/h to m/s by dividing by 3.6
- Do not confuse distance–time and speed–time graphs — read the axis labels first
- Average speed is NOT the average of two speeds when the times are different
Key facts from the syllabus (1.2)
- Distance–time graph: gradient = speed; horizontal line = at rest; straight line = constant speed; curve = changing speed
- Speed–time graph: gradient = acceleration; horizontal line = constant speed; area = distance travelled
- A negative acceleration (deceleration) means the object is slowing down
- Objects falling freely near the Earth with no air resistance accelerate at about 9.8 m/s²
- With air resistance, a falling object reaches terminal velocity when air resistance equals weight
- Extended the gradient of a curved speed–time graph at a point is found using a tangent
Textbook: §1.2 Motion, pp. 12–24
Define speed.
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Method: Speed is distance travelled per unit time.
Define velocity.
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Method: Velocity is speed in a given direction.
A cyclist travels 1800 m in 240 s. Calculate the average speed.
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Method: v = s ÷ t.
A car travels at 25 m/s for 40 s. Calculate the distance travelled.
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Method: s = v × t.
A bus travels 12 km in 20 minutes and then 18 km in 25 minutes. Calculate its average speed in km/h.
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Method: Average speed = total distance ÷ total time. Total time = 45 min = 0.75 h.
State what a horizontal line on a distance–time graph shows.
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Method: Distance is not changing.
State what a straight line with a positive gradient on a speed–time graph shows.
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Method: Speed increases at a steady rate.
A distance–time graph is a straight line from (0 s, 0 m) to (8.0 s, 56 m). Calculate the speed.
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Method: Speed = gradient of the distance–time graph.
A car accelerates uniformly from rest to 20 m/s in 10 s. Use the area under the speed–time graph to calculate the distance travelled.
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Method: Area of triangle = ½ × base × height.
A train moves at 15 m/s for 60 s, then decelerates uniformly to rest in 20 s. Calculate the total distance travelled.
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Method: Rectangle + triangle under the speed–time graph.
State the approximate value of the acceleration of free fall near the Earth's surface.
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Method: g is approximately constant near the surface.
A car travels 150 km in 2.5 h. Calculate its average speed in km/h.
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Method: v = d ÷ t.
Convert 72 km/h into m/s.
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Method: × 1000 ÷ 3600.
A sound travels 1700 m in 5.0 s. Calculate its speed.
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Method: v = d ÷ t.
A snail moves at 1.2 mm/s. Calculate the time it takes to move 30 cm.
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Method: t = d ÷ v; 30 cm = 300 mm.
State what a straight line with a positive gradient on a distance–time graph shows.
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Method: Steady speed.
State what a horizontal line on a speed–time graph shows.
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Method: Speed unchanged.
State what a curve getting steeper on a distance–time graph shows.
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Method: Speed increasing.
A distance–time graph shows a cyclist travelling 600 m in 120 s, stopping for 60 s, then travelling a further 400 m in 80 s. Calculate the average speed for the whole journey.
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Method: Total distance ÷ total time.
A lift accelerates uniformly from rest to 3.0 m/s in 2.0 s, moves at 3.0 m/s for 8.0 s, then decelerates uniformly to rest in 2.0 s. Calculate the distance travelled.
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Method: Area under graph (trapezium).
State how the distance travelled is found from a speed–time graph.
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Method: Area.
State how the speed is found from a distance–time graph.
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Method: Gradient.
A ball rolls 4.5 m in 1.5 s at constant speed. Calculate its speed.
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Method: v = d ÷ t.
Define acceleration.
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Method: Acceleration is change in velocity per unit time.
A sprinter accelerates from rest to 9.0 m/s in 2.5 s. Calculate the acceleration.
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Method: a = Δv ÷ Δt.
A car slows from 28 m/s to 12 m/s in 4.0 s. Calculate the acceleration and state what the sign means.
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Method: a = (v − u) ÷ t.
A speed–time graph is a curve whose gradient gets smaller with time. Describe the motion.
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Method: Gradient of a speed–time graph = acceleration.
A tangent drawn to a speed–time curve passes through (2.0 s, 3.0 m/s) and (6.0 s, 11.0 m/s). Calculate the acceleration at that point.
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Method: Acceleration = gradient of the tangent.
A ball falls from rest with no air resistance. Calculate its speed after 2.5 s (g = 9.8 m/s²).
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Method: v = u + at with u = 0 (from a = Δv/Δt).
Describe the motion of a skydiver from leaving the plane until reaching terminal velocity.
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Method: At first weight > air resistance so she accelerates at about 9.8 m/s². As speed increases, air resistance increases, so the resultant force and the acceleration decrease. When air resistance = weight, resultant force is zero.
Explain why an object dropped on the Moon falls with constant acceleration all the way down.
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Method: The Moon has no atmosphere, so there is no air resistance; the only force is weight.
A cyclist decelerates uniformly from 12 m/s to rest in 6.0 s. Calculate the deceleration and the distance travelled.
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Method: a = Δv/Δt; distance = area of triangle.
A car accelerates at 2.5 m/s² for 6.0 s from 10 m/s. Calculate its final speed.
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Method: Δv = a × t.
A train decelerates at 0.50 m/s² from 30 m/s. Calculate the time it takes to stop.
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Method: t = Δv ÷ a.
State how acceleration is found from a speed–time graph.
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Method: Gradient.
A speed–time graph shows a straight line from (0, 4.0 m/s) to (5.0 s, 14 m/s). Calculate the acceleration and the distance travelled.
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Method: Gradient; trapezium area.
A negative gradient on a speed–time graph is described as deceleration. Calculate the deceleration if speed falls from 18 m/s to 6.0 m/s in 3.0 s.
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Method: Gradient.
A parachutist opens the parachute while falling at terminal velocity. Describe and explain the motion until a new terminal velocity is reached.
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Method: Air resistance increases suddenly.
An object falls freely from rest for 1.5 s (g = 9.8 m/s²). Calculate its speed.
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Method: v = gt.
A stone falls from rest and hits the ground at 19.6 m/s (no air resistance). Calculate the time of fall and the height using the speed–time graph.
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Method: t = v/g; area of triangle.
Challenge questions
Harder, multi-step questions at the top end of the exam. Attempt these once you are confident with the questions above.
A car accelerates uniformly from 5.0 m/s to 25 m/s in 8.0 s, travels at 25 m/s for 12 s, then brakes uniformly to rest in 5.0 s. Calculate (a) the total distance, (b) the average speed.
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Method: Area: trapezium + rectangle + triangle.
A cyclist travels 6.0 km at 20 km/h and then 6.0 km at 12 km/h. Calculate the average speed for the whole journey. Explain why it is not 16 km/h.
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Method: Find each time.
Car A leaves a town at 60 km/h. Car B leaves the same town 30 minutes later along the same road at 90 km/h. Calculate how long after B leaves it catches A.
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Method: A has a 30 km head start; closing speed 30 km/h.
A distance–time graph is a straight line from (0, 0) to (10 s, 40 m), horizontal to 15 s, then a straight line to (25 s, 100 m). Calculate the speed in each section and the average speed.
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Method: Gradients.
A train must travel 4.5 km between stations. It accelerates uniformly from rest to 30 m/s in 50 s and decelerates uniformly to rest in 40 s. Calculate the time spent at constant speed.
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Method: Distance while changing speed = ½×30×50 + ½×30×40.
A ball is dropped from rest from a height of 20 m (g = 9.8 m/s², no air resistance). Using a speed–time graph, calculate (a) the time to hit the ground, (b) the speed at impact.
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Method: h = ½ × t × gt = ½gt².
A car moving at 30 m/s brakes with a deceleration of 6.0 m/s². The driver's reaction time is 0.70 s. Calculate the total stopping distance.
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Method: Thinking distance + braking distance (area of triangle).
A ball is thrown vertically upwards at 14.7 m/s (g = 9.8 m/s²). Calculate (a) the time to reach the top, (b) the maximum height, (c) the total time before it returns to the hand.
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Method: Deceleration at 9.8 m/s².
A speed–time graph for a sprinter is a curve. Tangents drawn at 1.0 s and 4.0 s have gradients 6.0 m/s² and 1.5 m/s². Describe the sprinter's motion and explain how the resultant force changes.
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Method: Decreasing acceleration.
A skydiver reaches a terminal velocity of 55 m/s, opens the parachute, and 4.0 s later has a new terminal velocity of 6.0 m/s. (a) Calculate the average deceleration. (b) Explain, in terms of forces, why the speed falls and then becomes constant.
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Method: Δv/Δt.
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