A fly is sitting on the back windshield (inside)a car moving in the forward direction at 50 mph. The fly hen fly's to the front windshield at .5 mph, how fast is the fly traveling?
0.5 mph relative to the car, 50.5 mph relative to the road outside, thousands of mph relative to its path around the sun.
The fly would be flying at 50.5 mph unless someone opens the window and it's sucked out. Then it's at splat speed
He's flying at 5 MPH in a capsule of air that's moving at 50 MPH, so his over ground speed is 55 MPH. He only needs to flap his wings enough to make the 5 MPH because the air he's in is already traveling at 50 MPH.
Adjust my response to .5 MPH - I didn't notice the decimal point.
You forgot the speed of the rotation of the earth on its axis!
Ernst Mach and Albert Einstein would ask, "relative to what?" I think Gilbert has the right idea in that regard.
This is a variation on a familiar theme. Sometimes it's about jumping up and down in a falling elevator so as to lessen the odds of being on the floor when it hits; other times, it involves a child running along the inside of a train in the direction opposite the train's travel; other times, it's one of the musings of pilots considering the possibility of a 120-knot housefly.
Here's how it works:
A 100-knot Cessna, flying over mountains at an altitude of 7,000 feet MSL (mean sea level), is enjoying a tailwind of, say, 20 knots. Its speed and altitude can be interpreted in a number of ways.
In terms of time and space, the Cessna has an across-the-ground speed of 120 knots and if it were to hit a theoretical brick wall in the sky, that's the amount of force with which it would impact.
As far as the air around it is concerned, the airplane is moving at 100 knots. But wait! As the airplane is traveling at 7,000 feet MSL, where the air is significantly less dense than at sea-level, the airspeed indicator will be showing an airspeed of only 86 knots. But wait! Though the airplane is at an altitude of 7,000 feet according to the altimeter, in fact it is lower than that because of the mountainous terrain (and then, there's more mumbo-jumbo about pressure-altitude, density-altitude, standard temperature and a few other things I've forgotten since ground school). I should mention that the real fun comes in when pilots discuss "The Downwind-Turn," which deals with an airplane's speed as it turns from upwind to downwind.
And so it is with the fly on the back of your windshield. It depends on how you look at it. In any case, if it encounters the windshield of your Model T from the outer-side of the windshield as you're racing along at a breakneck 30 MPH, it will bounce off the glass and give you a dirty look.
Bob: I believe the 'Downwind-Turn' follows the cross wind flight.
Swat the fly and be done with it!
A fly never flies in a straight line; a fly curves around, loops, doubles back etc. We should figure the fly's flight path; how much speed he looses flying a curve in relation to a straight tangent etc. All this in relation to the speed of the car, earth and so forth. Does the frog hanging on the windshield really care? The fly is open -- to further discussion. :-)
In a similar vein, you are driving a Model K Ford Six at the Michigan State Fair's new track in 1907. You need to circle the one mile track twice in two minutes. You forgot to advance your spark on the first lap and only made 30 mph. How fast do you have to go on the second lap?
A tree fell in the forest, did you hear it. By the way it fell on your fly sorry.
Down wind turn will open a bigger can of worms than what oil is best for a T. Few modern pilots experience the effects of a downwind turn, so they assume that it is no different than any other turn. I have even heard a well respected aviation writer say that at 10,000 feet, it did not matter which direction the wind was blowing in a turn, what he did not understand is that a down wind turn is always done at or below pattern altitude, and that is where a marginally powered aircraft encounter the adverse conditions if the pilot does not understand the dynamics of the situation.
Tyrone you have too much time on your hands!! LOL
You done and used your two minutes.
Sorry, Im straying from the topic, but what I want to know is. Would any of you pilots fly a airplane with a Model T engine.???
You mean like this?
I doubt it has a good enough power to weight ratio, which is pretty important in an airplane. You might need to run it through a gearbox to get the propeller RPMs high enough, too
Ive seen some pics and info of model T powered airplanes but was wondering if any are being flown today.
The great thing about the T engine is that you would not have to run a gear box to reduce the RPM. The higher the RPM the smaller the propeller that can be used and a larger propeller will give better results. The diameter of a prop is often limited by how far the crankshaft is from the ground when on the ground with the tail up. I would have no problem flying a T powered aircraft.
I've thought about this when operating my trackhoe. When the machine is traveling at 5 mph, how fast are the tracks moving? They're not moving at all on the bottom, so I figure they must be moving at 10 mph on the top.
I need to add that the propeller size is usually limited by the maximum engine RPM, when putting a gear or belt reduction an an aircraft, then the amount of reduction is determined by how large a propeller can be accommodated by the aircraft.
The old question. What's the last thing that goes through a fly's mind when it hits the windshield of a car traveling at 48.6 miles and hour and the fly is traveling in the opposite direction at 2.4 miles an hour?
I'm too fat for 20 hp to get me off the ground, but yeah, if i were the FAA 170lb guy, I'd fly a T powered Piet.
The real question about the fly is this: When it comes to rest on the ceiling of the car, does it do a loop to get there, or just get real close and suddenly flip upside down?
What I wanna know is why the normal whiners aren't complaining about this thread not being about Model T Fords.
PS I'm not complaining. I love it.
I sense this may be an eggnog sponsored thread. Like Makers Mark with mine.
Ha Ha Gary!!! That's one of my favorites!!!
Just to keep Fred happy,this thread isn't as boring as most of the K threads,but it's a close second.
Hey Jack, I'm happy.....just makin an observation.
Have a couple of eggnogs, Uncle Jack, you'll feel better about it all.
Mythbusters elevator of death episode. The dummy jumps at the exact moment of impact of a 9 story free falling elevator car. Problem is he's going at the same speed the elevator is. Approx 45/50 mph. The speed of his upward jump is negligible. Hence the title elevator of death.
I always understood that the biggest attraction to using a model T or A engine is because they put out their maximum torque at very low RPMs.
Boats and airplanes work best with large slow turning props.
All the Piets I have seen have model B engines in them.
If a fish swims from one end of the tank to the other will it change the weight of the tank ends?
You really need to find a way to get off of dial up. If you did you would find that there is more on the net than Model K threads! You might even find that the counter weights of an elevator weigh more than the loaded cab and in an total failure would actually fall up! A loaded elevator is actually pushed down.
PS. I like Model K threads!
Fred since you asked imho the answer lies at the top of the main page. I don't think threads such as this are likely to result in pejoratives and invectives.
Just my take.
The original question first starts to be real interesting if the car travels close to speed of light and the fly is able to fly as fast as that also.
If you are a passenger on a supersonic plane, can you speak to the person in front of you?
Then again, some theoretical physicists are now saying the entire universe may be a holographic illusion.
And don't forget that the sun travels through our galaxy, which in turn travels through the universe. Our Earth orbits the sun and travels at a different speed though the universe depending upon which side of its solar orbit it is on.
Drive carefully, and enjoy, W2
There is a theory, that if matter achieved zero speed, relative to a truly stationary center point in space, it would cease to exist.
(And I love the model K threads!)
Good night Gracie
I've heard these ...
If your traveling at the speed of light and turn on your headlights will they work?
If your traveling at the speed of sound and blow your horn will you hear it?
A friend of mine from back in my Air Force days with several degrees in mathematics ended up for a year or so teaching math to high school classes in Germany. He knew math just fine, but was still a little shaky sometimes on his German. He was presenting the class with a relative velocity problem involving shooting a bullet from a moving train in a direction perpendicular to the train's motion. The point was that the bullet was affected by the motion of the train, the explosion that sent it on its way in the first place, and gravity. What my friend couldn't understand was why the students were laughing so hard.
The verb for "shoot" in German is "schiessen" (schiessen, schoss, geschossen). Unfortunately, there is a similar verb, "scheissen" (scheissen, shiess, geschiessen). (Google it if you don't know what it means.) Instead of shooting from a moving train, his example involved.... well, you know.
If you got Einstein involved he would also need to consider the speed of our solar system in Goldilocks zone of our Milky Way Galaxy, the rotation of our galaxy and the speed at which our galaxy was travelling away from the point of origin thanks to the impetus of the big bang some 15 billion years ago. All for the speed of a fly in a car doing 50mph. Jim Patrick
So Germany has a different rule about:
"i" before "e" except after "c"?
Just like a T....in some instances a minor difference makes a big change...
As long as we're talking fun stuff, here's one:
A car accelerates rapidly. A book on the seat slides to rear as you would expect. However, a helium balloon floating in the car moves FORWARD.
Why? (You can look it up on the net)
ASAIK the Pietenpol was designed and built around a Model A engine, the later Peitenpol Scout was designed and built around a Model T engine. It was a single seater and is what is on display at the museum. I've flown a Piet with a Model B engine and it was OK, I flew another with a 65 HP Lycoming or Continental in it and it was much better.
Every car on the highway below was traveling faster than the Piet was and with a little head wind you could actually lose ground. A couple flights was enough, I don't know who he sold it to but it wasn't me.
Dave, the difference with the "i before e" rule is that English pronounces both versions the same (e.g. receive and believe), but German pronounces "ei" like our "eye" and "ie" like our "ee." I think where my friend's confusion came in was the difference with the past tense (or maybe the conditional), and he just picked the wrong one.
To answer the original question, only if you are traveling north-south, if you are traveling east-west you need to add/subtract 25000 mph from the equation.
Also, our cars must travel faster than we think at night. We can almost out drive our headlights.
Doug, only wreck I ever had I was coming back through Wyoming on a dark and stormy night night, wind was blowing so hard it blew the light off in the ditch and I couldn't see where I was going, wrecked the pickup.
Back in about 1982 I got aboard a flight test 757. Vacuum toilets were new to Boeing, and for some reason they put the biffy tanks in front, even for the aft toilets. The vacuum sucked the flush in an overhead pipe they called a 90 mph poop chute. That meant when you were cruising mach .92, and somebody flushed, you had supersonic sheiss.
The first time they flushed a vacuum toilet on the MD-11, it sucked the sidewalls in. They forgot to vent the room.
The story of the fat woman flushing an airliner toilet while sitting on it, is legendary. The DC-8 Flight Engineer had to go back and slip his hand between her legs to break the seal....
I've always been fascinated by the fact that if I am on a plane flying 300 mph and I walk to the front of the plane, I AM MOVING FASTER THAN THE PLANE!
OK, for you railroad fans:
What part of a train is always moving backwards compared to the rest of the train?
thomas, the track?
The top of every wheel!
Well,.....wait a minute,......no,.....the BOTTOM of every wheel!
Hey Harold, I figured you being from the age of steam trains and all would have said smoke from the stack! ; )
Harold is right, the bottom of the flange, below the top of the rail, is actually going opposite to the rest of the train. That's why the railroads sometimes grease the flanges on sharp curves.
Can't ever be too sure about that smoke Floyd! That all depends upon which way the wind is blow'n!