Speed Examples in Physics

Start with the recap, study the fully worked examples, then use the practice problems to check your understanding of Speed.

This page combines explanation, solved examples, and follow-up practice so you can move from recognition to confident problem-solving in Physics.

Concept Recap

The rate at which an object covers distance over time, calculated as total distance divided by total time, always expressed as a non-negative scalar quantity.

How fast you're going, ignoring which way—just the magnitude of motion.

Read the full concept explanation →

How to Use These Examples

Read the first worked example with the solution open so the structure is clear.
Try the practice problems before revealing each solution.
Use the related concepts and background knowledge badges if you feel stuck.

What to Focus On

Core idea: Speed starts by naming what changes, over what time interval, and whether direction matters.

Common stuck point: Students often know a formula related to speed but skip the recognition step: Am I describing motion over time with position, distance, direction, speed, velocity, or acceleration clearly separated? That leads to a correct-looking substitution attached to the wrong physical model.

Sense of Study hint: Ask: Am I describing motion over time with position, distance, direction, speed, velocity, or acceleration clearly separated?

Worked Examples

Example 1

easy

A jogger runs

5 \text{ km}

25 \text{ minutes}

. What is the average speed in m/s?

Answer

s \approx 3.33 \text{ m/s}

First step

Convert units:

5 \text{ km} = 5000 \text{ m}

and

25 \text{ min} = 1500 \text{ s}

Full solution

2
Use the average speed formula: $s = \frac{d}{t}$ .
3
Average speed: $s = \frac{5000}{1500} \approx 3.33 \text{ m/s}$

Speed is the rate at which distance is covered. Unlike velocity, speed is a scalar and does not include direction.

Example 2

medium

A train travels

120 \text{ km}

60 \text{ km/h}

and then

120 \text{ km}

40 \text{ km/h}

. What is the average speed for the whole trip?

Example 3

medium

A motorcycle covers the first

150 \text{ km}

50 \text{ km/h}

and the next

150 \text{ km}

75 \text{ km/h}

. Find the average speed for the whole trip.

Example 4

medium

An object's speed-time graph is a horizontal line at

12 \text{ m/s}

from

t = 0

t = 8 \text{ s}

. Find the distance travelled.

Practice Problems

Try these problems on your own first, then open the solution to compare your method.

Example 1

easy

Light travels at

3 \times 10^8 \text{ m/s}

. How far does light travel in

1 \text{ minute}

Example 2

medium

A runner completes the first half of a race (

5 \text{ km}

) at

10 \text{ km/h}

and the second half at

15 \text{ km/h}

. What is the runner's average speed for the entire race?

Example 3

easy

A car covers

100

m in

5

s. Find its speed.

Example 4

easy

Convert

36

km/h to m/s.

Example 5

easy

A runner moves at

4

m/s for

10

s. Distance covered?

Example 6

easy

Is speed ever negative?

Example 7

easy

A walker takes

50

s to cover

150

m. Find the speed.

Example 8

easy

A car's velocity is

-15

m/s. What is its speed?

Example 9

easy

Light travels

300{,}000

km in

1

s. Speed in km/s?

Example 10

easy

A snail covers

0.5

m in

100

s. Find its speed.

Example 11

medium

A car travels

80

m in

4

s and then

60

m in

2

s. Find the average speed.

Example 12

medium

A jogger runs

2

km in

10

min. Express the speed in km/h.

Example 13

medium

A particle's speed is

6

m/s. How long to cover

90

Example 14

medium

Two runners cover the same

400

m: A in

50

s, B in

80

s. Whose speed is greater and by how much?

Example 15

medium

A car goes

30

m/s for the first

2

s and

10

m/s for the next

6

s. Average speed?

Example 16

medium

A wheel point moves

0.4

m each rotation and completes

5

rotations in

2

s. Find its speed.

Example 17

challenge

A car travels half the distance at

30

km/h and half at

60

km/h. Find the average speed.

Example 18

challenge

A car travels equal times at

30

and

60

km/h. Find the average speed and explain why it differs from the equal-distance case.

Example 19

challenge

A dog runs back and forth at

10

m/s between two walkers approaching each other; the walkers take

120

s to meet. Total distance the dog runs?

Example 20

medium

A car covers

45

m in the first

3

s and

45

m in the next

9

s. Find the average speed.

Example 21

medium

A wheel point travels

0.6

m per revolution, doing

4

revolutions in

3

s. Find its speed.

Example 22

medium

A runner covers

1500

m in

5

min. Express the speed in m/s.

Example 23

easy

A cyclist covers

240 \text{ m}

20 \text{ s}

. Find the average speed.

Example 24

easy

Convert

72 \text{ km/h}

to m/s.

Example 25

easy

A car drives

90 \text{ km}

1.5 \text{ h}

. Find the speed in km/h.

Example 26

easy

A particle moves at

8 \text{ m/s}

for

12 \text{ s}

. Find the distance travelled.

Example 27

easy

Convert

108 \text{ km/h}

to m/s.

Example 28

medium

A car drives

50 \text{ km}

north, then

50 \text{ km}

south, both at

50 \text{ km/h}

. Find the average speed and the average velocity.

Example 29

medium

A walker covers

1.2 \text{ km}

20 \text{ min}

. Find the speed in m/s.

Example 30

medium

A car covers

40 \text{ km}

80 \text{ km/h}

, stops for

30 \text{ min}

, then covers

60 \text{ km}

60 \text{ km/h}

. Find the average speed for the whole journey.

Example 31

medium

A train must cover

480 \text{ km}

6 \text{ h}

. What constant speed is needed?

Example 32

medium

A runner finishes a

5000 \text{ m}

race in

20 \text{ min}

. Find the speed in m/s and km/h.

Example 33

medium

A particle's position vs time:

x = 0

t = 0

x = 30

t = 5 \text{ s}

x = 30

t = 8 \text{ s}

. Find the average speed over

[0,8]

Example 34

medium

Light travels at

3 \times 10^8 \text{ m/s}

. How long does light from the Sun (distance

1.5 \times 10^{11} \text{ m}

) take to reach Earth?

Example 35

medium

A bus driver claims an average speed of

60 \text{ km/h}

over a

90 \text{ km}

route. How many minutes should the trip take?

Example 36

hard

A car travels

\frac{1}{3}

of the distance at

30 \text{ km/h}

and

\frac{2}{3}

60 \text{ km/h}

. Find the average speed.

Example 37

hard

A train of length

200 \text{ m}

moves at

36 \text{ km/h}

. How long does it take to fully cross a

400 \text{ m}

platform?

Example 38

hard

Two cars start

300 \text{ km}

apart and drive toward each other at

40 \text{ km/h}

and

60 \text{ km/h}

. When and where do they meet?

Example 39

hard

A boat moves at

8 \text{ km/h}

in still water. A river flows at

3 \text{ km/h}

. Find the boat's speed when going downstream and when going upstream.

Example 40

hard

On a

200 \text{ km}

trip a driver's average speed is

50 \text{ km/h}

for the first half by distance. What constant speed for the second half makes the overall average

60 \text{ km/h}

Example 41

hard

Bird A flies at

12 \text{ m/s}

east; bird B flies at

5 \text{ m/s}

west. Find the speed of A relative to B.

Example 42

challenge

A cyclist averages

20 \text{ km/h}

on a flat stretch. To average

30 \text{ km/h}

over a round trip (same flat stretch out and back), what speed is needed on the return?

Example 43

challenge

A car covers equal time intervals of

1 \text{ s}

at speeds

5, 10, 15, 20 \text{ m/s}

. Find the average speed and the total distance.

← Back to Speed Formula Explained Practice Mode

Related Concepts

Velocity Average Speed Instantaneous Speed

Background Knowledge

These ideas may be useful before you work through the harder examples.

velocity