离心机环境下杆能否垂直于桶底保持平衡？
Awesome question—let’s break this down like we’re picking apart a carnival ride physics hack. Let’s start with the key context: we’re in a non-inertial frame (the spinning bucket), so we have to account for both gravity and that 6g outward centrifugal push.
First, let’s define "down" in the bucket
You noted the bucket tilts ~75 degrees to balance the centrifugal force and gravity. Here’s the critical thing: that tilt isn’t random—the bucket’s flat bottom ends up perpendicular to the combined pull of centrifugal force and gravity.
Think of it this way: if you were inside the bucket, you’d feel like the floor is perfectly level, and "down" would be the direction pointing straight toward the bucket’s bottom. That combined force (centrifugal + gravity) is what we call "effective gravity" in this spinning frame.
So what about the vertical rod?
When you say you’re placing the rod "completely vertical" relative to the bucket’s bottom, that means it’s pointing directly opposite to that effective gravity—exactly like standing a broomstick upright on your kitchen floor.
From inside the bucket, it’ll feel totally normal, and it’ll stay balanced just as it would on stationary ground. If you watched from outside the bucket, the rod would look tilted (along with the bucket), but inside? It’s as upright as can be.
A couple edge cases to keep in mind
- If the rod is perfectly thin (no width at the base), it’s in neutral equilibrium—place it exactly right and it stays, but even a tiny nudge sends it over. But any real rod with a solid base will have stable equilibrium.
- If the spin speed changes suddenly, the effective gravity direction shifts, which could topple the rod. But under the constant-speed scenario you described, it’s solidly balanced.
Bottom line
Yes, the rod will stay balanced when placed perpendicular to the bucket’s flat bottom. It’s all about aligning with the effective gravity of the spinning frame—no magic, just good old vector addition!
内容的提问来源于stack exchange，提问作者kim holder
