When do I use this k5 Kinematic Equation

[EASports555]

Vƒ = velocity final
Vi = velocity initial
a=acceleration
t=time
0.5 = ½
^2 = squared
- = minus
d = displacement
Equation
d = Vƒt - 0.5at^2

 

[mpresic3]

I look at your equation, and it has 4 variables; d, vf, a, and t.
I look at the list you have in parentheses and there are 5 variables (vi, a, vf, t, and d)
Clearly one of the variables in parentheses is not in the equation. Which one is it? That will tell you the variable that you do not have.

That seems to be the answer, but I do not see how that is going to be useful to you. Is this part of a more elaborate, or better stated problem? Are you trying to find the initial velocity? If you are, it looks like you will need some other equation.

 

[PeroK]

Summary:: What Variable do I not have when I use this equation? ( Vi = velocity initial , a = acceleration, vf = velocity final, t = time, d= displacement)

Vƒ = velocity final
Vi = velocity initial
a=acceleration
t=time
0.5 = ½
^2 = squared
- = minus
d = displacement
Equation
d = Vƒt - 0.5at^2

With any equation you can find a single unknown quantity if you know all the others. The equation: $$d = v_ft - \frac 1 2 at^2$$ has four quantities. If you know any three, then you can calculate the fourth. This may require you to rearrange the equation. For example, if you know $d, v_f$ and $t$, then you can find the acceleration by rearranging the equation to: $$a = \frac{2(v_ft - d)}{t^2}$$ And you can calculate $a$ by plugging in the known quantities: $d, v_f$ and $t$.