hello, I been doing physics homework and I came across this problem that i think i know how to do but for some reason i cannot get the right answer! any help will be very appreciated(adsbygoogle = window.adsbygoogle || []).push({});

thanks a lot:)

1. The problem statement, all variables and given/known data

The highest waterfall in Canada is the Della Falls in B.C. with a change in elevation of 440 m m. When the water has fallen 12% of its way to the bottom, its speed is 33 m/s. Neglecting air resistance and fluid friction, determine the speed of the water at the top of the waterfall.

answer in the book: 5.0 m/s

2. Relevant equations

Ek = 1/2 mv^2

Ep = mgh

3. The attempt at a solution

This is what i tried,

i found what 12% of 440 m is, and it ended up to equal 52.8 so i subtracted it by 440 m to get 387.2 m as the height after the water has fallen 12% of its way to the bottom.

Ek1 + Ep1 = Ek2 + Ep2

(masses cancel out) and we are left with

1/2 v^2 + gh = 1/2 v^2 + gh

1/2 v^2 + (9.81)(440) = 1/2 (33)^2 + (9.81)(387.2)

and i get v= 66 m/s (dont think it is right but it is possible that the book might be wrong)

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