t=6s S=66m Vt=15m/s a=? V0=?

Question

maybe it's easy for you

Answer 1

We have the definition of average velocity as :
average velocity = (displacement / duration)
also in constant acceleration motion because the velocity increases constantly the average velocity can easily calculated averaging the initial and final velocity , thus :
average velocity = (initial velocity+final velocity)/2
since the left side of these relation is the same , the right side should be the same , so we have;
(displacement / duration) = (initial velocity+final velocity)/2
multiplying by 2 we yield;
initial velocity+final velocity = 2*(displacement / duration)

substituting the desire parameters yields for the initial velocity :
initial velocity = 2* (66 /6) - 15 = 22- 15 =7m/s
also to calculating acceleration we should use the definition which yields,
a=(Vt-Vo)/t = (15-7)/6 = 1.33 m/s^2

Answer 2

It is.

The acceleration is a constant, so the velocity vs time curve is a line. The integral of the velocity curve is the distance traveled. The area of a trapezoid is 1/2(H1+H2)*base, so 1/2(Vf+V0)*t =S, the distance traveled. This results in V0=7m/s