Starting from the constant-acceleration kinematic equations, write a formula that gives xf in terms of t, xi, vf, and a.

xf

if xf is final distance...

xf=vi^t+1/2 a t^2
or
xf=vf*t/2

To derive a formula that gives the final position (xf) in terms of time (t), initial position (xi), final velocity (vf), and acceleration (a), we can start with the constant-acceleration kinematic equation:

xf = xi + v_avg * t

where xf is the final position, xi is the initial position, v_avg is the average velocity, and t is the time.

To express v_avg in terms of vf and a, we use another kinematic equation:

vf = vi + a * t

Here, vi is the initial velocity. Assuming that the object starts from rest (vi = 0), we can simplify the equation to:

vf = a * t

To find v_avg, which is the average of the initial and final velocities, we can use the formula:

v_avg = (vi + vf) / 2

Since vi = 0, this simplifies to:

v_avg = vf / 2

Now we can substitute v_avg into the first equation:

xf = xi + (vf / 2) * t

So, the formula that gives xf in terms of t, xi, vf, and a is:

xf = xi + (vf / 2) * t