A car in a roller coaster moves along a track that consists of a sequence of ups and downs. Let the x axis be parallel to the ground and the positive y axis point upward. In the time interval from t=0 to t=4 s, the trajectory of the car along a certain section of the track is given by(adsbygoogle = window.adsbygoogle || []).push({});

(look at attachment)

where [tex]A[/tex] is a positive dimensionless constant.

I have two questions that i dont get:

1.) Derive a general expression for the speed [tex]v[/tex] of the car.

Express your answer in meters per second in terms of [tex]A[/tex] and [tex]T[/tex].

if i get the derivate of r, respect to time, that would get me the velocity right? so... 3at^2-12t+a

2.) The roller coaster is designed according to safety regulations that prohibit the speed of the car from exceeding 20m/s . Find the maximum value of [tex]A[/tex] allowed by these regulations.

V = V(0) + at

20 = 0 + a(4)

a= 5

did i get any of this right? if not, please give me a hand

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