The acceleration of force is given by :
At t = - 5 s :
There is no force acting so accleration is zero and u = 10 m/s
or
or
At t = 25 s :
Acceleration is - 20 m/s2 and u = 10 m/s
or
or
At t = 100 s
We have acceleration for first 30 sec, and then it will move with constant speed.
So for 0 < t < 30 :
or
or
Now for t > 30 s :
We need to calculate velocity at t = 30 sec which will be used as the initial velocity for 30 < t < 100.
or
Now
or
or
Hence total displacement is : - 8700 + (- 41300 ) = - 50000 m.