Solving for Time Given Acceleration & Initial Velocity

[kara123]

Homework Statement

Which equation would you use to determine the displacement of an object moving with uniform acceleration given a value for acceleration?

Relevant Equations

a. ∆d=vi∆t+(aav(∆t)^2)/2
b. Vf=Vi+aav∆t
c. ∆d=[(vf+vi)/2]∆t
d. vf^2 =vi^2+(2aav∆d)

assuming initial velocity is 0 and we have the value for acceleration I'm unsure how to still use any of those equations because you must have a time value at least or a final velocity

 

[TSny]

You are thinking correctly. If the value of the acceleration is the only thing that you know, there is no way to determine the displacement.

 

[kuruman]

You are thinking correctly. If the value of the acceleration is the only thing that you know, there is no way to determine the displacement.

Although I agree with your assessment, I don't think that the author of the question meant to imply that the acceleration is the only given quantity. This looks like a question where one needs to show an understanding of what the equations say. Of the four choices, only two are expressions for displacement. Of these, only one has acceleration on the right-hand side.

A clearer statement of the question might have been

Which equation would you use to determine the displacement of an object moving with uniform acceleration if one of the given quantities is the value of the acceleration?​

 

[haruspex]

A clearer statement of the question might have been
Which equation would you use to determine the displacement of an object moving with uniform acceleration if one of the given quantities is the value of the acceleration?

You would still have the choice of expressing the displacement as a function of any two of initial velocity, current velocity and time.