posted by Ted
Starting from the constant-acceleration kinematic equations, write a formula that gives xf in terms of t, xi, vf, and a.
in terms of vf?????
yes in terms of vf. we are asked to combine different kinematic equations to drive xf. I believe the equation v=vo+at^2 can sub for vo. does this make sense?
v = Vi + a t
vf = Vi + a T so Vi = vf-aT
x = xi + Vi t + (1/2) a t^2
xf = xi +(vf-aT)t + (1/2) a t^2
if t = T final time
xf = xi + vf T - a T^2 + (1/2) a T^2
xf = xi + vf t - (1/2) a t^2
ok, it just changes the sign of the at^2 term
(It still uses the AVERAGE speed during the interval !!)