Recent content by TheOldDog

I learned this 50 yrs ago. You, yourself, just pointed out the connection between weight and mass. Or are you saying using the mass of liquid displacement and the mass of the vessel yields different results than using the weight of each ...??? As for why I used mass? Like I attempted to...

Exactly my thought at the time. *thumbsup* (My brain was thinking in weights, which is how I learned it, but when I posted I went to metrics because I know a LOT of science is in metrics these days - much more so than when I was in school back in the stone age.)

I love Mission of Gravity! There was nothing in there that seemed odd at all. (I thought the use of a bowl instead of the outer surface of a sphere for a map was genius!) In the SciFi novel I was reading the hull is rigid and the artificial gravity did not vary over the positions covered in the...

Fairly simple - I think - but I may have missed something; HS physics was decades ago. If a boat in a body of water on Earth has a draft of 1m, will the draft of the boat in a similar body of water on, say, Mars have the same draft? (Assume the same temperature of water.) I figured the change...

Isn't it amazing how many people in the world don't understand this? :-(

When someone earlier mentioned weight, as opposed to load, it threw me off since weight is strictly a downward (toward gravity) force. If lift is always perpendicular to thrust and thrust is always in the direction of travel, with load and drag, respectively, being opposite those forces, I...

? I always thought lift was "up" - but it seems to me you're saying lift has a horizontal component when the airplane is changing altitude?

Work requires a displacement. Since there is no displacement (change in up/down) in level flight there is no work being done in that direction.

Got it. I think that set me on the right course, so to speak. :) I was getting messed up with Bernoulli and flight but thinking about it in light of HallsofIvy's hint Bernoulli's principle seems more like buoyancy, or at least very similar.

So if the airplane rises it must expend at least the same amount of energy from the engine (assuming no losses) as the change in gravitational potential (plus whatever is needed to overcome drag/friction)?

Consider a simple prop plane like a Cessna. I'm a little confused about the origin of the energy for lift. We know the engine accounts for all the thrust and the wings have drag that varies by angle of attack, which also changes lift. But does the engine account for all the energy in lift? If...