Speed, Distance, and Time
Speed
Speed refers to the rate at which a particular distance is covered by an object in motion.
It helps the students to understand the basic and higherlevel math concepts in a better way.
Speed is measured as the distance travelled per unit of time.
Let us explain it with an example.
Example:
The speed of a car is 90 kilometres per hour. This means that the car has travelled 90 kilometres of distance in 1 hour.
Time
Time refers to an interval between two events.
Example:
A train took 4 hours to reach Delhi from Agra. This means that the difference in time to reach Delhi starting from Agra is 4 hours.
Distance
Distance means the length between two points.
These two points are starting point and the end point (or destination).
Example:
A train travelled 242 kilometres to reach Delhi from Agra. This means that the distance between Agra (starting point) and Delhi (end point) points is 242 kilometres.
Units Used for Speed, Time, and Distance
Speed, distance, and time are represented in different units.
 Units that are generally used for time are second, minute, and hour.
 Units that are generally used for distance are metre, kilometre, mile, feet, etc.
 Units that are generally used for speed are m/s, and km/h.
Relation Between Speed, Time, and Distance
Time is directly related to distance. That means, if the speed remains unchanged then time will increase if the distance is increased and the time will decrease if the distance is decreased.
Distance = Speed Ă— Time
Example:
A train is moving at a speed of 40 km/h. In the next 2 hours, how much distance will it cover?
Answer:
The speed of the train is 40 km/h implies that it is travelling 40 km in one hour.
So, in this problem
Time (hour)  Speed (km/h)  Distance(km) 
2  40  ? 
distance = 40 Ă— 2 = 80 km
Speed is directly related to distance. That means, if the time remains unchanged then the distance will increase if the speed is increased and the distance will decrease if the speed is decreased.
Example:
Raju has travelled 60 km and Sanju has travelled 55 km/h. in 5 hours. Find their speeds.
Answer:
In 5 hours, Raju and Sanju have travelled 60 km and 55km respectively.
So,
Time (hour)  Speed (km/h)  Distance(km) 
5  ?  60 
5  ?  55 
Rajuâ€™s speed is
60 Ă· 5 = 12 km/h
Sanjuâ€™s speed is
55Ă· 5 = 11 km/h
Hence, Rajuâ€™s and Sanjuâ€™s speeds are 12 km/h and 11km/h respectively.
Speed is inversely related to time. That means, if the distance remains unchanged, then the time will increase if the speed is decreased and the time will decrease if the speed is increased.
Example:
The distance between the school and the house of Riya is 36 km. At the time of going to school, the bus driver was driving at a speed of 36 km/h, and at the time of returning home the bus driver was driving at a speed of 18 km/h. Find how long the bus driver takes to reach the school, and to return home.
Answer:
The distance between school to home is 36 km.
So,
Time (hour)  Speed (km/h)  Distance(km) 
?  36  36 
?  18  36 
When going to school the bus driver took
36 Ă· 36 = 1 hour
When returning back to home, it took
36 Ă· 18 = 2 hours.
Speed, Time, and Distance Unit Conversions
Conversion of speed units

To convert km/h to m/s, multiply it with
5 / 18
So, 1km/ h5 / 18m/s 
To convert m/s to km/h, multiply it by
5 / 18or 3.6
So, 1km/ h5 / 18km/h = 3.6 km/h
Conversions of time units
 1 hour = 60 minutes = 3600 seconds
 1 minutes = 60 seconds

1 second =
1 / 3600hour

1 second =
1 / 60minutes

1 minute =
1 / 60hour
Conversions of distance units
 1 km = 1000 m = 100000 cm

1 m =
1 / 1000km

1 cm =
1 / 100m

1 cm =
1 / 10000km