Dr Gulshan S. answered 06/05/20
Physics Teaching is my EXPERTISE with assured improvement
Part A X = 5t3 +2t +3
At t=2 S
Position X = 5 (2)3 + 2*2 +3 = 40+4 + 3= 47 m or units as in question for units of X
Part B
Speed = dX/dt
so derivative of X wrt t
dX/dt = d/dt ( 5t3 +2t +3) = V
= 15 t2 +2t +0
Plug in t = 2 sec
Part C
Acceleration = d/dt ( V)
d/dt( 15t2 +2t) = a
= 15*2 t +2 unit m/s
=30t +2 = 62 m/s2 ( For t= 2 Sec)

Arturo O.
(B) v=15t^2+2 (C) a=30t This will change the numbers in the answers.06/05/20