Question related two different ways to do solution

Thread starter helloword365
Start date Apr 12, 2025

AI Thread Summary

The discussion revolves around the different methods used to solve a problem involving cross-section sidelengths. One method expresses the sidelength as 8-8x/3, while the other relies on similar triangle relationships. The user questions the correctness of both approaches and seeks clarification on which answer is accurate, either 470 kJ or 117 kJ. There is also a suggestion to try the integral method indicated in red. The conversation highlights the complexities of solving the problem and the potential for multiple valid approaches.

Apr 12, 2025

helloword365

Homework Statement: An upside-down square pyramid with a height of 3 m and side lengths of 8m is filled to the brim with water. How much work is needed to lift all the water out of the container through the top. (ρ = 1000 kg/m3, g = 9.8 m/s2)

Relevant Equations: Work = Force * displacement

My work:

Answer Key (red font one) *may not be right.

My question is why is sidelength of cross section written as 8-8x/3, while my way of doing it doesn't involve that (involves suspicious similar triangle relationships)? Which answer (if any) is right here? 470 kj or 117 kj? Thank you!

Last edited by a moderator: Apr 13, 2025

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Apr 12, 2025

haruspex

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Did you try doing the integral in red?

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