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August 6

Engineering question: water flowing through a steel pipe.

Is there a formula in engineering that takes into account velocity, temperature, and friction? Say at room temperature you have water flowing through a horizontal steel pipe. If you increase the T of the water and steel pipe to 50 C, water will flow faster due to less friction. So about how much faster would it flow, would it be like 1% faster? 67.165.185.178 (talk) 15:56, 6 August 2022 (UTC).[reply]

As you propose, the main effect of temperature is on other properties. "Friction" involves both the pipe surface (not sure how much that changes for small changes in temperature) and the nature of the fluid itself. Temperature might have a substantial effect on the viscosity of the fluid, and possibly also its density. Flow also depends on pressure, so one would have to keep that constant (or include that as an additional variable). And it all depends how turbulent vs laminar the flow is. Some lead topics include include Reynolds number and dynamic and kinematic viscosity. DMacks (talk) 16:16, 6 August 2022 (UTC)[reply]

See Darcy–Weisbach equation. Dolphin (t) 23:01, 8 August 2022 (UTC)[reply]

Plant question: does UV harm fruit more after it left the plant?

So like cherries, nectarines. If you have an apple that fell off the true, and is now on direct sunlight, does the UV harm the fruit or berry more? I believe berries like blueberries can still do respiration a little longer after being plucked, but other fruit essentially instantly stop respiration. If that were a factor. 67.165.185.178 (talk) 16:00, 6 August 2022 (UTC).[reply]

I have never heard that fruit stop respiring once severed from the mother plant. They are still doing metabolic processes, with the best known being ripening and the production of ethylene. Even if they aren't doing much respiring, they should have all kinds of mechanisms working to protect the fruit and seeds within. Abductive (reasoning) 01:02, 7 August 2022 (UTC)[reply]

Some fruits and vegetables can continue to ripen after picking, but some don't. Here's a decent list of what does and what doesn't. Sunlight hitting picked fruits that can't ripen any further may or may not be harmful, but it's not going to do much good and the warmth may encourage spoilage. Matt Deres (talk) 13:23, 7 August 2022 (UTC)[reply]