The acceleration of a bus is given by ax (t) = at, where a = 1.2 m/s3.If the bus's velocity at time t = 1.0s is 5.0 m/s, what is its velocity at time t = 2.0 s?

Answer 1

sorry. acceleration a is in m/s^2
and what the heck is ax(t) = at?

In any case, if a is constant, v(2) = v(1) + a
That's what acceleration is -- how much the velocity changes in a second.
a = ∆v/∆t where ∆t=1 in your question.

Answer 2

V = Vo + a*t.
5 = Vo + 1.2*1.0,
Vo = 3.8 m/s.

V = Vo + a*t. = 3.8 + 1.2*2 = __m/s.