rocket question

Question

A rocket of mass 1499 kg accelerates at 494 m/s^2 for 40 s from an initial speed of 3100 m/s. How fast will be the rocket be traveling after 40 s?

Answer 1

a(t) = 494

v(t)= integral of a(t) = 494t + initial velocity

= 494t + vo

= 494t + 3,100

v(40) = 494(40) + 3,100 = 19,760+3100 =22,860 m/s