Question

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

a) Work out the
acceleration, in km/h²,
in the first 15 mins.
120
100
80
b) Work out the distance
between the two cities. 60
40
c) Work out the average
speed of the train during 20
the journey.
0
9am
10am
Time
11am

Answer 1

a) in the first 15 mins

∆ v = 15 km/h

∆ t = 15 mins =
`(1)/(4)h`

So
`a = (∆v)/(∆t) = ( (50)/(1) )/(4) = 200 \: km/ {h}^(2)` Ans.

b) [ The area enclosed by the chart is the distance ]

`= 50 * (1)/(4) * (1)/(2) + 50 * (1)/(2) + (50 + 100) * (1)/(4) * (1)/(2) + 100 * (1)/(2) + 100 * (1)/(2) * (1)/(2)`

`= 125 \: km` Ans.

c)
`average \: \: speed = (125)/(2) = 62.5 \: km/h` Ans.