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

                         

        (Contd…) HomeTree

      BACK

NOTE: The units of time and distance determine the unit of measurement of speed.  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. BACK

1000 m = 1 km 1 hr = 60 min 1 min = 60 sec   1 hr = 60  60 sec 1 m = km   1 sec = 1 60  60 hr  (Contd…)

= 90 x 5 m 18 sec 1) Changing the speed given in km/hr into m/sec. e.g. 90km/hr = 90 x 1000 m 60 x 60 sec km/hr = 25 m/sec (Contd…)

 50m/sec = 50 x 60 x ) Changing the speed given in m/sec into km/hr. 50m/sec = 180km/hr 5 3 e.g. 50m/sec = 1 60 x 60 hr  km x x 60 = = 50 x 18 km 5 hr 1 10

To convert the speed given in km/hr into m/sec, multiply the given speed by 5 18  BACK To convert the speed given in m/sec into km/hr, multiply the given speed by 18 5

DISTANCE TIME SPEED = DISTANCE SPEED TIME = If you know any of the two of the three variables, (distance, speed and time) you can find out what the other one is. Easy Way to Remember the Distance Formula: I stay in DSTREET. (DST are in the order as in the Distance Formula.)  DISTANCE = SPEED X TIME BACK

Enter Speed   Enter Time 40m/sec DISTANCE = SPEED X TIME 10sec =X 40 m/sec 10 sec = 400m BACK

= 27 x 5 18  Enter Distance Enter Speed 30m 27km/hr Conversion: Speed = 27km/hr 3 Distance & speed are not in the same unit of measurement, so conversion is required m/sec = 2 ( Contd…….)

= 30 m 15/2 m/sec = 30 X = 4 sec. TIME = 4 seconds BACK DISTANCE SPEED TIME =

 Enter Time Enter Distance 2 hrs 45 min 132 km Conversion : Time = 2 hrs 45 min hr 45 min = Time is given in both hour and minute so this can be converted into hour. 4 3 Time = 2 hrs + 45 min OR ( Contd…….)

3 4 hr 45 min =  2 hrs + 45 min 4 = 2 hr + 3 hr (Contd…….) = hr 4 = 11 hr 4 (Contd…….)

1 DISTANCE TIME SPEED = = 132 km 11/4 hr 4 11 = 132 X 12 SPEED = 48 km/hr BACK

The distance between Pune and Nasik is 352 km. A bus running at the speed of 40 km/hr left Pune at hrs. What time will it reach Nasik? TIME = DISTANCE  SPEED 352 km 40 km/hr = 5 44 = 5 hrs = hrs += 4 5 hr = 8 hrs and X 60 min = 8 hrs and 48 min The bus started at hrs and travelled for a period of 8 hrs 48 min. (Contd…) 

 the bus reached at hrs hrs = hrs = 4 hrs and 48 min Contd… To find the time of the day according to the 24 hours system, let us subtract 24 from hrs min The bus reached Nasik early morning the next day at 4 hours and 48 minutes. BACK

TRAIN GOES PAST A POLE 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. 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 train’s length. What does the phrase “train goes past a pole mean”? (Contd…)

SOLUTION : The length of the train will be equal to the distance travelled in the given time with the same speed. DISTANCE = SPEED X TIME DISTANCE = SPEED X TIME Speed = 36 km/hr Distance = 10m/sec x 20 sec = 200 m Time = 20 sec = 36 x m/sec = km/hr Conversion: BACK

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.  BACK

 1 hr = 60  ______ sec 1 m = 1 km  To convert the speed given in km/hr into m/sec, multiply the given speed by 5 18 Speed = Distance Time = Distance Speed Time Distance = ___________ X Time  1 sec = 1 ___  ___ hr 60 Speed BACK

Created by Department of Research The End