The graph below describes the journey of a train between two cities

Step-by-step explanation:

To find : Acceleration in first 15 min . Distance between two cities  Average speed of journey

Solution:

Each horizontal block is 1/8 hr = 7.5 min

Each vertical block is 10 km/hr

Time                    Velocity  km/hr

0 Min  ( 0 hr)            0

15 Min (1/4 hr)           50

45 Min (3/4 hr)         50

60 MIn  ( 1 hr)            100

90 Min  ( 3/2 hr)        100

120 Min ( 2hr)            0

Acceleration in first 15 min  (1/4 hr)  =  (50 - 0)/(1/4 - 0)  = 50/(1/4)

= 200  km/h²

Distance between two cities

= (1/2)(0 + 50)(1/4 - 0)  + 50 * (3/4 - 1/4)  + (1/2)(50 + 100)(1 - 3/4)  + 100 * (3/2 - 1) + (1/2)(100 + 0)(2 - 3/2)

=  25/4  + 25 + 75/4   + 50 + 25

= 125

Distance between two cities = 125 km

Average Speed of journey = 125/2  = 62.5  km/hr

Acceleration in first 15 min = 200  km/h²

Distance between two cities = 125 km

Average Speed of journey =  62.5  km/hr

Hope this helps..

is only a line? i think so