A submarine took 9 hours to complete a journey. For the first 5 hours, it travelled at an average speed of 106 km/h. For the rest
of the journey, it travelled at an average speed of 125 km/h.
What was the total distance of the journey?

1030 km

Explanation:

t= 9 hours

t1= 5 hours

s1= 106 km/h

d1 + d2= d

t1 + t2 =t

5 hours + t2 =9 hours

t2= 5 hours - 9 hours

t2= 4 hours

s2= 125km/h

d= ?

s= d/t

s1= d1/t1

106= d1/5

d1= 106 x 5

d1= 530km

s2= d2/t

125= d2/4

d2= 125 x 4

d2= 500km

d= d1 + d2

d= 530 + 500

d= 1030km

the minimum constant speed at which she can catch the train is 2.7 m/s

given:

acceleration = 0.6

time = 4.5 s

to find:

velocity = ?

formula used:

from 1st kinematic equation we get,

v = u + at

u = initial speed of train = 0 m/s

v = final speed of the train

a = acceleration of the train

t = time

solution:

from 1st kinematic equation we get,

v = u + at

u = initial speed of train = 0 m/s

v = final speed of the train

a = acceleration of the train

t = time

v = 0 + (0.6 × 4.5)

v = 2.7 m/s

the minimum constant speed at which she can catch the train is 2.7 m/s