An object starts from rest at the point (1,2,3) and moves with an acceleration of i-vector + 2j-vector.?

Question

Find the position of the object at t = 4

Any help is greatly appreciated < : )

Answer 1

a = acceleration
v = velocity
s = position

a(t) = i + 2j
v(t) = it + 2jt
s(t) = it²/2 + jt² + P

s(t) = <1, 2, 3> + t²<1/2, 1, 0>

Plug in t = 4

s(4) = <1, 2, 3> + <8, 16, 0> = <9, 18, 3>

Answer 2

Just add 0.5*1*4^2 to i and 0.5*2*4^2 to vector j.