MATHEMATICS

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Bombay Cambridge Gurukul
Bombay Cambridge Gurukul
Time, Distance and Speed
MATHEMATICS STANDARD VII
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Contents

• Time, distance and speed concept
• Units of Measurement
• Conversion
• Important formulae
• Calculate distance using formula
• Calculate time using formula
• Calculate speed using formula
• Word Problems
• Train goes past a pole
• Time, distance and speed in daily life

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Time, Distance Speed- Concept
Home
Tree
In the picture above the girl is going really
fast. She catches up and passes the boy. Can you
say who is slower?
The boy is slower than the girl. Can you say why
is the boy slower than the girl?
The boy is slower than the girl because the boy
takes more time to cover the same distance.
(Contd)
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We can also say that the speed of boy is less
than that of the girl.
When a person covers a given distance in a given
time then the person is said to be in motion and
the rate with which he/she moves is called speed.

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Units of Measurement
The units of measurement of distance are km, m,
cm etc.
The units of measurement of time are hour (hr),
minute (min), second (sec).
The units of measurement of speed are km/hr and
m/sec, cm/sec etc.
NOTE The units of time and distance determine
the unit of measurement of speed.
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Conversion
1000 m 1 km
1 hr 60 min
1 min 60 sec
\ 1 hr 60 60 sec
(Contd)
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1) Changing the speed given in km/hr into m/sec.
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3
5
10
2
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90 km/hr 25 m/sec
(Contd)
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2) Changing the speed given in m/sec into km/hr.
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5
10
1
50m/sec 180km/hr
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Easy way to Remember Conversion
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Important Formulae
DISTANCE SPEED X TIME
DISTANCE
TIME
SPEED
Easy Way to Remember the Distance Formula I
stay in DSTREET. (DST are in the order as in the
Distance Formula.)
If you know any of the two of the three
variables, (distance, speed and time) you can
find out what the other one is.
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I) CALCULATE DISTANCE FROM SPEED AND TIME
10
sec
DISTANCE SPEED X TIME
10 sec
40 m/sec
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II) CALCULATE TIME FROM DISTANCE AND SPEED
Distance speed are not in the same unit of
measurement, so conversion is required.
Conversion Speed 27km/hr
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2
( Contd.)
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30 m

15/2 m/sec
2
4 sec.
1
TIME 4 seconds
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III) CALCULATE SPEED FROM TIME AND DISTANCE
132 km
Time is given in both hour and minute so this can
be converted into hour.
Conversion Time 2 hrs 45 min
OR
Time 2 hrs 45 min
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4
( Contd.)
15
(Contd.)
(Contd.)
16
12
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SPEED 48 km/hr
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Word Problems
The distance between Pune and Nasik is 352 km. A
bus running at the speed of 40 km/hr left Pune at
20.00 hrs. What time will it reach Nasik?
TIME DISTANCE SPEED
8 hrs and 48 min
The bus started at 20.00 hrs and travelled for a
period of 8 hrs 48 min.
(Contd)
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Contd
\ the bus reached at 20.00 hrs 8.48 hrs
28.48 hrs
To find the time of the day according to the 24
hours system, let us subtract 24 from 28.48 .
4 hrs and 48 min
The bus reached Nasik early morning the next day
at 4 hours and 48 minutes.
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TRAIN GOES PAST A POLE
Q. A train running at the speed of 36 km/hr goes
past a pole in 20 seconds. Find the length
of the train.
What does the phrase train goes past a pole
mean?
This means that the train has to travel a
distance equal to its length to go past the pole.
Hence, the time required to go past a pole is the
same as the time required to travel a distance
equal to the trains length.
(Contd)
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SOLUTION
The length of the train will be equal to the
distance travelled in the given time with the
same speed.
Speed 36 km/hr
Time 20 sec
Conversion
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6
36 km/hr
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1
DISTANCE SPEED X TIME
Distance 10m/sec x 20 sec
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200 m
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Time, Distance and Speed in Daily Life
Speed, time and distance is one of the basic
tools a sailor uses in navigation. Using these
simple formulae he can predict the time of
arrival, the speed of travel or the distance he
has to cover.
In athletic events and elimination rounds speed,
distance and time play a major role in the making
and breaking of records.
The departure and arrival of aeroplanes, trains
and buses depends on calculations involving
speed, time and distance.
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Fill in the blanks and complete the following
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60
1 hr 60 ______ sec
Check It Out
1000
Time
Speed
Speed
Distance ___________ X Time
BACK
60 60
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The End
Created by Department of Research