Motion

Learn it by playing

Answer these questions to earn energy, then fish and explore. No account needed.

For teachers: ready-to-use lesson slides, revision notes, diagrams for Motion (Physics, CIE) — use them in your lesson, or run the topic as a live class game.

Notes

Speed & Velocity

**Speed** = distance travelled per unit time; a **scalar** quantity (magnitude only).
Equation: v = \frac{s}{t}, where v in m/s, s in m, t in s.
**Average speed** = total distance / total time; useful when speed varies.
**Velocity** = speed in a given direction; a **vector** quantity (magnitude and direction).
Velocity uses **displacement** (vector) instead of distance.
Same speed but different directions → different velocities.

Acceleration (Extended)

**Acceleration** = rate of change of velocity; a = \frac{\Delta v}{\Delta t}, units m/s².
Change in velocity: \Delta v = v - u (final minus initial).
**Positive acceleration** = speeding up; **negative acceleration (deceleration)** = slowing down.
Any change in velocity (speed up, slow down, change direction) is acceleration.
Formula triangle: cover the quantity to find; a = \frac{\Delta v}{\Delta t}, \Delta v = a \times \Delta t, \Delta t = \frac{\Delta v}{a}.

Distance-Time Graphs

**Distance-time graph**: straight line = constant speed; horizontal line = stationary.
**Gradient** = speed; steeper slope = faster speed.
Curved line = changing speed (acceleration/deceleration); increasing gradient = speeding up, decreasing = slowing down.
To calculate speed: draw a large gradient triangle, find \frac{\Delta y}{\Delta x}.
Always check units (e.g., km → m, min → s).

Speed-Time Graphs

**Speed-time graph**: straight line = constant acceleration; horizontal line = constant speed (zero acceleration).
**Gradient** = acceleration; positive gradient = acceleration, negative = deceleration.
**Area under graph** = distance travelled.
Split area into triangles and rectangles: triangle area = \frac{1}{2}bh, rectangle area = bh.
Total distance = sum of all areas under the line.

Calculating Acceleration from Speed-Time Graphs (Extended)

For constant acceleration: gradient = \frac{\Delta v}{\Delta t} using a straight line.
For changing acceleration: draw a **tangent** at the point; gradient of tangent = instantaneous acceleration.
A tangent is a straight line that just touches the curve at that point.
Use a large gradient triangle on the tangent to calculate \frac{\Delta y}{\Delta x}.

Freefall

In absence of air resistance, all objects fall with same acceleration: **g = 9.8 \, \text{m/s}²** (acceleration of freefall).
Weight W = mg, where g is gravitational field strength (N/kg).
With air resistance: forces are weight (down) and air resistance (up).
Air resistance increases with speed; when it equals weight, resultant force = 0 → **terminal velocity**.
Skydiver: initially accelerates, then air resistance increases, eventually reaches terminal velocity; deploying parachute increases air resistance → deceleration to a lower terminal velocity.
In a vacuum (no air resistance), objects never reach terminal velocity; they accelerate at g continuously.

Distance-time graph showing constant speed (diagonal) then stationary (horizontal).

Speed-time graph showing acceleration, constant speed, and deceleration.

Speed-time graph for a skydiver: acceleration, terminal velocity, then deceleration after parachute opens.

Practice questions

Free preview — 8 of 40 questions. Sign up to see them all.

1.Which of the following is a scalar quantity?
Easy
- Avelocity
- Bdisplacement
- Cacceleration
- Dspeed
2.What is the acceleration of free fall near Earth's surface?
Easy
- A9.8 m/s
- B9.8 m/s²
- C9.8 m/s² downward
- D9.8 N/kg
3.On a distance-time graph, a horizontal line indicates that the object is:
Easy
- Aaccelerating
- Bmoving at constant speed
- Cstationary
- Ddecelerating
4.Which of the following is the correct definition of velocity?
Easy
- ADistance travelled per unit time
- BSpeed in a given direction
- CChange in displacement per unit time
- DRate of change of speed
5.The area under a speed-time graph represents:
Easy
- Aacceleration
- Bvelocity
- Cdistance travelled
- Ddeceleration
6.A car travels 150 m in 10 s. What is its average speed?
Medium
- A15 m/s
- B1500 m/s
- C0.067 m/s
- D15 km/h
7.An object accelerates from 4 m/s to 10 m/s in 3 s. What is its acceleration?
Medium
- A2 m/s²
- B3 m/s²
- C4 m/s²
- D6 m/s²
8.On a speed-time graph, a straight line with negative gradient represents:
Medium
- Aconstant acceleration
- Bconstant deceleration
- Cconstant speed
- Dincreasing acceleration

More questions

9.A skydiver falls from a plane. After reaching terminal velocity, the parachute opens. Which statement is correct?
Hard
- AThe skydiver immediately stops falling.
- BThe skydiver accelerates upward.
- CThe skydiver decelerates to a lower terminal velocity.
- DThe skydiver continues at the same terminal velocity.
10.Which of the following is true for an object falling in a vacuum near Earth?
Hard
- AHeavier objects fall faster than lighter ones.
- BAll objects fall with the same acceleration.
- CObjects eventually reach terminal velocity.
- DAcceleration decreases as speed increases.
11.A car travels at 20 m/s for 5 s, then at 30 m/s for 10 s. What is the total distance travelled?
Medium
- A100 m
- B300 m
- C400 m
- D500 m
12.A cyclist travels 360 m in 60 s. What is the average speed in m/s?
Medium
- A6 m/s
- B60 m/s
- C0.17 m/s
- D10 m/s
13.A car travels along a straight road. The speed-time graph for the car's journey is a straight line from (0 s, 0 m/s) to (10 s, 20 m/s). What is the acceleration of the car?
Medium
- A2 m/s²
- B0.5 m/s²
- C20 m/s²
- D10 m/s²
14.The speed-time graph of a skydiver shows a curve that becomes horizontal. What does the horizontal section represent?
Medium
- AThe skydiver is accelerating
- BThe skydiver is stationary
- CThe skydiver is moving at terminal velocity
- DThe skydiver is decelerating
15.A student drops a stone from a cliff. Air resistance is negligible. Which graph shows how the speed of the stone changes with time?
Hard
- AA straight line with positive gradient starting from origin
- BA curve with decreasing gradient starting from origin
- CA horizontal line starting from origin
- DA straight line with negative gradient starting from origin
16.A train travels 120 m in 54 s. What is its average speed?
Medium
- A2.22 m/s
- B0.45 m/s
- C6.48 m/s
- D6480 m/s
17.The speed-time graph of a car consists of a triangle from 0 to 10 s (speed increasing from 0 to 20 m/s) followed by a rectangle from 10 to 30 s (constant speed 20 m/s). What is the total distance travelled?
Hard
- A500 m
- B400 m
- C600 m
- D300 m
18.An object is moving at constant speed in a circle. Which statement about its velocity is correct?
Medium
- AVelocity is constant because speed is constant
- BVelocity changes because direction changes
- CVelocity is zero
- DVelocity is equal to speed
19.Which quantity is a vector?
Easy
- ASpeed
- BDistance
- CVelocity
- DTime
20.A skydiver jumps from a plane. Which statement about the forces acting on the skydiver is correct when terminal velocity is reached?
Hard
- AWeight is greater than air resistance
- BAir resistance is greater than weight
- CWeight equals air resistance
- DThere are no forces acting on the skydiver
21.A car decelerates from 30 m/s to 10 m/s in 5 s. What is the deceleration?
Medium
- A4 m/s²
- B8 m/s²
- C-4 m/s²
- D-8 m/s²
22.The distance-time graph for a cyclist is a straight line sloping upward. What does this indicate?
Medium
- AThe cyclist is stationary
- BThe cyclist is moving at constant speed
- CThe cyclist is accelerating
- DThe cyclist is decelerating
23.A ball is thrown vertically upwards. Air resistance is negligible. Which graph shows how the velocity changes with time? (Take upward as positive.)
Hard
- AA straight line with negative gradient crossing the time axis
- BA straight line with positive gradient crossing the time axis
- CA curve decreasing then increasing
- DA horizontal line
24.What is the acceleration of free fall near the Earth's surface?
Easy
- A9.8 m/s²
- B9.8 m/s
- C9.8 km/h
- D9.8 N/kg
25.A student measures the time taken for a ball to fall from a height of 2.0 m using a stopwatch. The student repeats the measurement five times and obtains the following readings: 0.64 s, 0.66 s, 0.63 s, 0.65 s, 0.67 s. What is the most likely value for the time of fall?
Medium
- A0.65 s
- B0.64 s
- C0.66 s
- D0.63 s
26.A student investigates the motion of a trolley rolling down a ramp. She measures the distance travelled by the trolley every 0.2 s using a ticker-tape timer. The tape shows dots that are initially close together and then gradually become further apart. What does this pattern indicate about the motion of the trolley?
Hard
- AThe trolley is accelerating.
- BThe trolley is moving at constant speed.
- CThe trolley is decelerating.
- DThe trolley is stationary.
27.A student uses a motion sensor to plot a distance-time graph for a moving object. The graph is a straight line with a positive gradient. Which statement about the object's motion is correct?
Medium
- AThe object is moving with constant speed.
- BThe object is accelerating.
- CThe object is stationary.
- DThe object is moving with increasing speed.
28.In an experiment to determine the acceleration of free fall, a student drops a steel ball from a height of 1.5 m and measures the time of fall using a light gate. The measured time is 0.55 s. Which of the following is the most likely reason for the discrepancy between the measured acceleration (calculated from s = ½at²) and the accepted value of 9.8 m/s²?
Hard
- AAir resistance acting on the ball.
- BThe height was measured incorrectly.
- CThe ball was not dropped exactly from rest.
- DThe light gate timing was triggered late.
29.A student uses a stopwatch to measure the time for 20 oscillations of a pendulum. She records 30.4 s. What is the time for one oscillation?
Easy
- A1.52 s
- B30.4 s
- C0.66 s
30.A car travels at a constant speed of 20 m/s for 10 s. It then decelerates uniformly at 2 m/s² until it stops. What is the total distance travelled by the car?
Medium
- A300 m
- B200 m
- C100 m
- D400 m
31.A skydiver jumps from a plane. Which of the following speed-time graphs best represents her motion from the moment she jumps until just before she opens her parachute?
Hard
- AA curve that starts with a steep positive gradient, then gradually becomes less steep and finally horizontal.
- BA straight line with constant positive gradient.
- CA curve that starts with a shallow positive gradient, then becomes steeper and finally horizontal.
- DA straight line with constant negative gradient.
32.A student measures the speed of a moving trolley using two light gates connected to a datalogger. The trolley passes the first gate at time 0.00 s and the second gate at time 0.25 s. The distance between the gates is 0.50 m. What is the average speed of the trolley between the gates?
Medium
- A2.0 m/s
- B0.125 m/s
- C0.50 m/s
- D4.0 m/s
33.A student plots a speed-time graph for a moving object. To find the acceleration at a particular instant, she draws a tangent to the curve at that point and calculates its gradient. Which of the following is the correct reason for drawing a tangent?
Hard
- AThe gradient of the tangent gives the instantaneous acceleration.
- BThe area under the tangent gives the distance travelled.
- CThe gradient of the tangent gives the average acceleration.
- DThe tangent shows the direction of motion.
34.Which of the following is a vector quantity?
Easy
- AVelocity
- BSpeed
- CDistance
- DTime
35.A ball is thrown vertically upwards. Air resistance is negligible. Which graph shows how the velocity of the ball changes with time? (Take upward as positive.)
Hard
- AA straight line with negative gradient crossing the time axis.
- BA straight line with positive gradient crossing the time axis.
- CA curve that decreases and then increases.
- DA horizontal line at positive velocity.
36.What is the definition of speed?
Easy
- ADistance travelled per unit time
- BChange in velocity per unit time
- CSpeed in a given direction
- DRate of change of displacement
37.What does a horizontal line on a distance-time graph indicate?
Easy
- AThe object is accelerating
- BThe object is moving at constant speed
- CThe object is stationary
- DThe object is decelerating
38.On a speed-time graph, what does the area under the graph represent?
Medium
- AAcceleration
- BDistance travelled
- CVelocity
- DDeceleration
39.An object accelerates uniformly from rest at 2 m/s² for 5 seconds. What is its final velocity?
Hard
- A10 m/s
- B2.5 m/s
- C0.4 m/s
- D20 m/s
40.Which of the following is true for an object falling in a vacuum near Earth's surface?
Medium
- AIt accelerates at 9.8 m/s² regardless of mass
- BIt falls at constant speed
- CHeavier objects fall faster
- DIt decelerates due to air resistance

Slides

Speed and Velocity

Speed is distance travelled per unit time. It is a scalar quantity (magnitude only).
Velocity is speed in a given direction. It is a vector quantity (magnitude and direction).
Equation: v = s / t, where v = speed/velocity, s = distance/displacement, t = time.

Which of the following is a vector quantity?

Speed
Distance
Velocity
Time

Average Speed

Average speed = total distance travelled / total time taken.
Useful when speed varies during a journey.
Example: A car travels 100 m in 20 s, average speed = 100/20 = 5 m/s.

Average speed = total ____ travelled / total time taken.

Acceleration (Extended)

Acceleration is the rate of change of velocity.
Equation: a = Δv / Δt, where Δv = change in velocity, Δt = time taken.
Units: m/s². Positive acceleration = speeding up; negative acceleration = slowing down (deceleration).

A car increases velocity from 10 m/s to 30 m/s in 5 s. What is its acceleration?

2 m/s²
4 m/s²
5 m/s²
20 m/s²

Distance-Time Graphs

A distance-time graph shows how distance changes with time.
Gradient = speed. Steeper gradient = faster speed.
Horizontal line = stationary. Curved line = changing speed (acceleration).

Which of these are true about distance-time graphs?

A horizontal line means the object is stationary.
The gradient gives the acceleration.
A curved line indicates constant speed.
A steeper line means a greater speed.

Speed-Time Graphs

A speed-time graph shows how speed changes with time.
Gradient = acceleration. Positive gradient = acceleration, negative = deceleration.
Area under the graph = distance travelled.

On a speed-time graph, what does the area under the graph represent?

Acceleration
Speed
Distance
Time

Calculating Acceleration from Speed-Time Graphs (Extended)

For a straight line, acceleration = gradient = Δy/Δx.
For a curve, draw a tangent at the point and find its gradient.
Example: If speed changes from 0 to 20 m/s in 10 s, gradient = 20/10 = 2 m/s².

The gradient of a speed-time graph gives the ____.

Freefall

In the absence of air resistance, all objects fall with the same acceleration, g = 9.8 m/s².
This is called acceleration due to gravity.
With air resistance, objects reach terminal velocity when weight = air resistance.

What is the acceleration of freefall near Earth's surface?

9.8 m/s
9.8 m/s²
9.8 m
9.8 N/kg

Terminal Velocity

When an object falls through air, air resistance increases with speed.
Eventually, air resistance equals weight, resultant force = 0, and speed becomes constant.
This constant speed is called terminal velocity.

Which statements about terminal velocity are correct?

Terminal velocity is reached when weight equals air resistance.
Terminal velocity is the maximum speed a falling object can reach.
Heavier objects always have a higher terminal velocity.
In a vacuum, objects also reach terminal velocity.

Freefall and Air Resistance

Without air resistance, objects accelerate at g = 9.8 m/s² constantly.
With air resistance, acceleration decreases until terminal velocity.
A skydiver initially accelerates, then reaches terminal velocity, then decelerates when parachute opens, then reaches a lower terminal velocity.

A skydiver jumps from a plane. After reaching terminal velocity, they open their parachute. What happens next?

They accelerate downwards.
They continue at the same speed.
They decelerate to a lower terminal velocity.
They stop immediately.

Unlock all 40 questions, slides & more

Create a free account to see every question, the slides, flashcards and revision notes for this topic.

Past papers

Past-paper practice for this topic is coming soon.

🗂️ Coming soon