Timeline for Magnet falling through tube
Current License: CC BY-SA 4.0
9 events
| when toggle format | what | by | license | comment | |
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| May 16, 2022 at 17:11 | comment | added | Stallmp | Sorry I meant if the magnet falls faster, the drag force $F_d$ will increase faster and balance the gravitational force $F_g$ | |
| May 15, 2022 at 18:31 | history | edited | Puk | CC BY-SA 4.0 |
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| May 15, 2022 at 17:56 | comment | added | Puk | I don't understand your argument of air drag balancing $F_d$, so I can't say what's wrong with it. I've edited my answer to try to clarify. I might be able to help if you tell me what part of it doesn't make sense to you. | |
| May 15, 2022 at 17:54 | history | edited | Puk | CC BY-SA 4.0 |
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| May 15, 2022 at 9:14 | comment | added | Stallmp | And because the magnet falls faster, the air drag will increase faster as well, despite a lower $k$ for aluminium, and balance the $F_d$. But something about my logic is wrong, because if you solve the differential equation, then the magnet in the copper tube will reach terminal velocity faster AND the terminal velocity is lower than the magnet in the aluminium tube. Where is the error in my logic? | |
| May 15, 2022 at 9:12 | comment | added | Stallmp | For some reason my old answer wasn't deleted, so ignore that comment please. I am for some reason still confused about this. Let's look at the situation of the magnet: 1. We drop a magnet in a copper tube and we drop the same magnet in an aluminium tube, so $F_g$ is the same in both cases. 2. We know that the drag $F_d = kv$, where k is directly proportional to the conductivity of the tube (assume tubes have same dimensions). 3. The constant $k$ is greater for copper, so you would think that the $F_d$ will balance $F_g$ faster. But at the same time for aluminium, the magnet falls faster | |
| May 15, 2022 at 8:52 | comment | added | Puk | @Stallmp I don't understand. Free fall isn't the relevant scenario, we are comparing terminal velocities in the presence of air resistance. | |
| May 15, 2022 at 8:39 | comment | added | Stallmp | I don't really think your analogy helps here. If you have a light ball and a heavy ball of the same size, they will accelerate downwards at the same rate in free fall. If you now consider air resistance, | |
| May 15, 2022 at 8:02 | history | answered | Puk | CC BY-SA 4.0 |