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## Homework Statement

A bolt is dropped from a bridge under construction, falling 85 m to the valley below the bridge. (a) In how much time does it pass through the last 28% of its fall? What is its speed (b) when it begins that last 28% of its fall and (c) when it reaches the valley beneath the bridge?

## Homework Equations

No idea.

## The Attempt at a Solution

I did .28 x 85 = 23.8 m. I also assumed g = 9.8 m/s^2, xinitial = 23.8, xfinal = 0, but I'm now lost. The five constant acceleration constants need v or t which I have neither.