Find the height of a free falling object

[KwamKwam]

Homework Statement

An object falls freely, moving 60m in the last 2 seconds. Find the height at which it was dropped.
[/B]

Homework Equations

Vf = 1/2(gt^2) + Vo(t)+ Yo
g= 9.8m/s^2[/B]

The Attempt at a Solution

the object accelerates at 9.8m/s^2 . and the velocity would be 30m/s. (60 divided 2) so do you plug in 30m/s and the acceleration of gravity and solve for Yo? (the initial position)[/B]

 

[BvU]

Dag KwamKwam, welcome to PF

You want to check your equation -- or precisely describe what you mean with Vf. Otherwise the dimensions don't fit.
To me it looks as if two equations from here have been squashed together. And you need both, I think.

 

[KwamKwam]

Thank you, Vf is the objects final velocity

 

[BvU]

You still want to check your equation. On the left you have m/s, on the right you have m + m/s + m . Can't be right !
Can you make sense of the expressions in the link I gave ?

 

[KwamKwam]

yeah I can. so my equations are V = Vo+ a(t) and X=Xo + Vo(t) + 1/2(at^2) instead of my first one?

 

[BvU]

Very good. a(t) and V₀(t) are confusing. Better write a t and V₀ t or a $\times$ t and V₀ $\times$ t

Now you have these two equations you want to sort out how to apply them. What to fill in, how to choose t = 0 and x = 0 and such. Any ideas ?

(bedtime for me, so others will have to help you further).

 

[KwamKwam]

so X₀ = 60, t = 2 and a = -9.8 and V₀is what we're searching for.

 

[haruspex]

so X₀ = 60, t = 2 and a = -9.8 and V₀is what we're searching for.

And X=?