This document discusses speed and how to calculate it. It defines speed as how fast an object is moving and explains that to calculate speed, the distance and time are needed. The key formula provided is: Speed = Distance / Time Several examples are given to demonstrate calculating speed using this formula, including Usain Bolt's speed during a 100m race. Different speed units for different contexts are also outlined such as miles/hour, km/hour, and m/s.

1. Speed
By Dr. Keja
Senior Researcher Fellow
City University London

2. Objectives
• Sense of speed
• How to calculate speed
• Understand the mean speed

3. Sense of Speed
58 km
in one
hour
360 km in one hour
920 Km in one hour
28,968 in one hour

4. Define speed
• Speed is to tell how ____________ an object is
moving.
• To calculate the speed __________ and _______
are needed.
• Choose from the following:
• distance, time, fast
fast
timedistance

5. Calculating speed
Speed=
Distance
Time

6. Remember the triangle of speed
d
s t

7. Do you know?
• Which has the highest speed?
Light
– 300000000 m/s in vacuum
– 200000000 m/s in glass

8. Unit for speed for practical purpose
distance time speed of unit
meter sec m/s
miles hour
Km Hour
Miles/hour
Km/hour

9. Units
UK
Miles/hour
US
Km/hour
d
s t

12. Usain Bolt record

13. Q1. Bolt ran 100 m in 9.58 sec. Calculate the speed of
Bolt.
• Distance = 100 m
• Time = 9.58 sec
d
s t
speed =
distance
time
=
100 𝑚
9.58 𝑠𝑒𝑐
= 10.43 𝑚/𝑠

14. True or False?
• Jey was driving in an area where the speed
limit was 50 Km/hour. She travels 10 Km in 10
minutes. She has broken the speed limit.
Object/Person Total distance Total time Average speed unit
Jey 60 Km 1 hour
10 Km 10 Minutes
60 Km 60 Minutes
60 Km/h

15. Complete Q2-Q5
Object Distance Time Speed
Q1 Flight 2 Km 3 secs
Q2 Leopard 232 Km 4 hours
Q3
Sound in
water
14820 m 10 second
Q4 Sound in air 3430 m 10 second

16. Q2. A flight travels 2Km in 3 sec. Calculate the speed
of the flight.
• Distance = 2 Km
• Time = 3 sec
• Speed =
d
s t
𝑑𝑖𝑠𝑡𝑎𝑛𝑐𝑒
𝑡𝑖𝑚𝑒
2 𝑘𝑚
3 𝑠𝑒𝑐
0.66 𝐾𝑚/𝑠

17. Complete Q2-Q5
Object Distance Time Speed
Q1 Flight 2 Km 3 secs
Q2 Leopard 232 Km 4 hours
Q3
Sound in
water
14820 m 10 second
Q4 Sound in air 3430 m 10 second
0.666 Km/s
58 Km/h
1482 m/s
343 m/s

18. Summary
• Speed=
𝐷𝑖𝑠𝑡𝑎𝑛𝑐𝑒
𝑇𝑖𝑚𝑒
• Speed can be used to calculate the distance
travelled by an object or person in a given
time.
d
s t