An object accelerates uniformly from rest at a rate of 2 m/s2 for 3 s and then 5 m/s2 for 15 s. Find its final velocity?

Answer 1

Do it in two parts.

Or, find the total impulse given

F=ma
1) F=m*2
2) F=m*5

Impulse=2m*3+5m*15
set that equal to the change in momentum mV, and solve for V

Answer 2

2m/s