226: Swingset

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Swingset

Title text: Someone bring me a pocket fan so I can drift around the yard.

Explanation

In the opening panel of this comic, Blondie, probably as Miss Lenhart, sees Cueball sitting on a swing set. She tells him that at the apex of his swing, he'll become weightless. Cueball then imagines that at the peak of his swing, he is able to become permanently weightless, floating above the ground without any support.

When on a swing or other pendulum rides, there is a moment between swinging up and swinging back down when the forces of gravity, friction, air resistance, etc., bring the velocity and normal force of the swing to zero. At this moment, there is no acceleration toward the pivot of the swing (since the centripetal acceleration is proportional to the square of the speed). So the swinger experiences no centripetal force. Of course, gravity still acts on the person, but if the swing is horizontal at that point, then there is no reaction force, so for one moment, the swinger is in free-fall and experiences weightlessness. However, that weightlessness can only be maintained for a fraction of a second, so if Cueball tried this in real life, he would come crashing to the ground.

In the title text, Cueball asks for a pocket fan, believing he could fly around the yard using this small device as a propeller. By using the fan to blow air in the opposite direction he wishes to travel, he could perhaps use the reaction force to push himself around. Note that this form of travel does not work at high altitudes because it works by pushing air molecules, which decrease in concentration at high altitudes. Another method of propulsion could be machine guns

Transcript

[Woman talking to Cueball on swing-set.]

Woman: You know, at the peak of a big swing, you become weightless.

[Thought bubble from Cueball.]

[Cueball swings higher and higher. At the peak of a big swing, he shoves himself off the swing. Cueball remains hovering in the air.]

Cueball: Hey guys. Come check this out.

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Discussion

A glass with water can be momentarily inverted at this moment and the water will not leave the glass!--DrMath 08:56, 16 November 2013 (UTC)

Isn't the point about illustrating that you do in fact have weight even in instences that are written off as weightless? In space you just happen to be falling at the same velocity of your surroundings, maintaining orbit simply by moving fast enough to miss the Earth. On top of which, in a low enough orbit g is still close to 9.8 m/s^2 if only because altitude is insignificant compared to the radius of the Earth.--Passing Stranger 14:10 August 2014 (UTC)

No, you don't have weight in some instances. Weight is dependent upon gravity, so in deep space with no planets or stars close enough to matter you would be weightless. Mass, on the other hand... 173.245.50.154 01:46, 10 January 2015 (UTC)

He was talking about orbit around a body, where in one sense you still have real weight. The bureaucrats on the ISS have nearly earth-normal weight, being only what, five percent farther from the center of the earth's mass? That weight is simply hidden by the fact that everything else around it has the same relative velocity, all of it falling at the earth and eternally missing, thanks to its forward velocity. I miss Douglas Adams. —Kazvorpal (talk) 01:48, 22 October 2019 (UTC)

The woman appears to be his mother. -- 173.245.52.173 (talk) (please sign your comments with ~~~~)

Nah, I think it's Miss Lenhart. 172.68.23.151 15:27, 3 October 2024 (UTC)

Weight is actually a description of reaction force; if you're in free fall, and therefore not being pushed on by the floor or pulled on by a rope, you are weightless. If you are being swung on a rope, the direction of your "weight" is constantly changing. This might seem arbitrary, but it avoids things like everyone on a rotating space station being considered "weightless" due to the lack of gravity; a closed physical system can't tell the difference between gravity and uniform acceleration. 108.162.238.159 08:51, 13 May 2015 (UTC)

When I'm alone in elevators, I'll sometimes jump right before the elevator stars to descend. Because I have to fall a longer distance than I jumped, it tricks my brain into feeling a moment of weightlessness more than what I feel at my apogee. I also sometimes like to float underwater for long periods of time, pretending I'm on the ISS. Unfortunately I'm fucking terrified of deep water, and due to my lack of water-based activity, I've quite declined in my ability to hold my breath underwater. I used to be able to do it for at least a minute to a minute and a half when I was 12. I used to either pretend I was Neo, or pretend I was on the ISS or generically in space. Never both, though. Now I can hardly do 20 seconds. Now that I really want to start swimming again, I can't. I grew up with a pool I hardly used, and now I'm in college, and all of our pools are lap-based. i.e. I can't hog 25sqft of space to just be all floaty in. I'd have to take up an entire lane, which I don't want to do. So the only way I'd really be able to experience this is if I scuba dived. Maybe I should do that again. It's the closest, for now, I'll ever get to feeling like I'm in space. Maybe later I can afford a Zero G flight. Maybe later I can do some space tourism stuff. Maybe later I'll be an actual astronaut. Only I'm two inches too short, for now, apparently -3- International Space Station (talk) 09:21, 27 October 2015 (UTC)

Guys, don't jump in elevators. Modern elevators have failsafes to detect unnatural changes in momentum. Jumping in an elevator can trigger it to come to a halt, and then you're stuck there until maintenance can come by to see if everyone is OK and what went wrong. You're now just wasting everyone's time. 162.158.91.91 18:22, 19 September 2024 (UTC)