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re: Let us ponder a fly in a train
Posted on 5/30/18 at 3:15 pm to toosleaux
Posted on 5/30/18 at 3:15 pm to toosleaux
In a vacuum, stationary until the wall hits it.
IRL, I'd suspect that the fly is light enough that the air that is pushed towards the front of the train car when it starts moving probably propels it with the train.
IRL, I'd suspect that the fly is light enough that the air that is pushed towards the front of the train car when it starts moving probably propels it with the train.
0
Posted on 5/30/18 at 3:15 pm to toosleaux
quote:
Does the fly remain stationary until the back wall strikes it, or does it begin to move forward along with the train?
When you are sitting in a car doing 20 mph and the driver punches the accelerator, do you get thrown further back in your seat? Yes you do.
The key is ACCELERATION.
Posted on 5/30/18 at 3:15 pm to toosleaux
What if I killed said fly with a fly-swatter?
Posted on 5/30/18 at 3:15 pm to LSUBoo
quote:see, now you are bringing in relative acceleration. The important thing to remember is that it’s all relative
It will move backwards a little at first as the train starts to accelerate faster than the air inside the compartment. Same reason you'll feel pushed back into your seat a little when it starts accelerating.
Posted on 5/30/18 at 3:16 pm to Boudreaux35
quote:
When have you ever seen a fly hover stationary?
Bingo... /thread
Posted on 5/30/18 at 3:16 pm to toosleaux
2 × 4 (9÷3) × 3 = ??
Posted on 5/30/18 at 3:17 pm to toosleaux
the fly hits the back of the car the trains motion is independent of the fly.
Posted on 5/30/18 at 3:18 pm to toosleaux
The fly exits at Sweetwater, has Teddy's loop and kills all the hosts.
Posted on 5/30/18 at 3:18 pm to bee Rye
quote:
see, now you are bringing in relative acceleration. The important thing to remember is that it’s all relative
Well the OP did say that the train begins to accelerate.
Posted on 5/30/18 at 3:18 pm to Sid in Lakeshore
quote:
do you get thrown further back in your seat? Yes you do.
While I agree you do, that is a product of the seat under your arse moving forward with the car. Remember, this fly is not in contact with the train.
Posted on 5/30/18 at 3:19 pm to toosleaux
The mother was the doctor....
Posted on 5/30/18 at 3:19 pm to toosleaux
If you've got a bug in your car and you slam into a wall at 100mph, that bug is hitting the windshield. If it we possible for the train to accelerate at the same speed with which the car decelerated, the fly would hit the back of the train.
Posted on 5/30/18 at 3:28 pm to toosleaux
The air in the train begins to move forward when the train begins to move forward. So would the fly. Think of the air as just another solid piece of the train that the fly is sitting on. Different story if the windows are open.
That is assuming a slow acceleration though.
That is assuming a slow acceleration though.
This post was edited on 5/30/18 at 3:30 pm
Posted on 5/30/18 at 3:30 pm to toosleaux
Shouldn't there be a "Deep Stoner Thoughts" board for threads like this?
Posted on 5/30/18 at 3:34 pm to NATidefan
quote:
That is assuming a slow acceleration though.
Yeah, in reality, the fly would essentially stay where it is relative to the train floor/wall/ceiling because the train won't accelerate fast enough for there to be any noticeable effect.
However, at the extremes, that fly would hit the back of the wall just like it would hit the windshield if the train came to a sudden halt from a great speed.
Posted on 5/30/18 at 3:37 pm to toosleaux
The confusing point is any meaningful effect, or potential lack thereof, of the air in the train on the fly.
A method of testing this would be to hold a small feather while traveling down the road in your car, then release it just as you slam on the brakes. Does it fly forward, or float straight down?
With something like a golf ball, the answer is clear, it'll fly forward. Its mass relative to any drag caused by differential speed to the air is very high.
The feather, and maybe fly, have a much lower mass relative to the drag they incur from moving through air.
A method of testing this would be to hold a small feather while traveling down the road in your car, then release it just as you slam on the brakes. Does it fly forward, or float straight down?
With something like a golf ball, the answer is clear, it'll fly forward. Its mass relative to any drag caused by differential speed to the air is very high.
The feather, and maybe fly, have a much lower mass relative to the drag they incur from moving through air.
Posted on 5/30/18 at 3:44 pm to toosleaux
I should know this. My uncle was a conductor.
This post was edited on 5/30/18 at 3:44 pm
Posted on 5/30/18 at 3:53 pm to CptRusty
quote:
The feather, and maybe fly, have a much lower mass relative to the drag they incur from moving through air.
Good point. There is a speed at which the fly would hit the windshield/back wall, but the air resistance, even inside the train/car, would make it unlikely in most real world acceleration scenarios.
Posted on 5/30/18 at 3:53 pm to Nado Jenkins83
quote:
better question, can a plane take off on a treadmill?
wait....do you think that a plane taking off goes forwards because the wheels????
Posted on 5/30/18 at 3:58 pm to toosleaux
If the railcar doors are closed, the fly moves with the train, because he is using the air inside the car for his "lift"
Like a toy in your car can fly around as he wants while your doing 80.
Like a toy in your car can fly around as he wants while your doing 80.
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