Airplanes and sailboats
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MortyD then why do we measure the specific
gravity of a suspension? Are not the particles in suspension analogous to particles in flite? Is not an airplane or a fruit fly a particle? Remove the mechanical energy and in both cases the solids settle out of the fluid. In one case the particle drops like a stone and in the other the flying object crashes. But in a contained system with nothing added or removed the mass remains unchanged.
gravity of a suspension? Are not the particles in suspension analogous to particles in flite? Is not an airplane or a fruit fly a particle? Remove the mechanical energy and in both cases the solids settle out of the fluid. In one case the particle drops like a stone and in the other the flying object crashes. But in a contained system with nothing added or removed the mass remains unchanged.
answers
sorry, i just noticed my first reply has vanished. if a five pound bird starts flying inside an airplane by creating its own lift, which is how birds fly, the airplane will lose five pounds of weight. just think of an open cockpit where the bird can fly as high as it wants, keeping pace with the airplane, or not.
sorry, i just noticed my first reply has vanished. if a five pound bird starts flying inside an airplane by creating its own lift, which is how birds fly, the airplane will lose five pounds of weight. just think of an open cockpit where the bird can fly as high as it wants, keeping pace with the airplane, or not.
MortyD, When your five pound bird leaves
the open cockpit the void is filled with air. But in a pressurized airframe whether the bird is at rest or in flite its presence still has displaced the air equal to its volume and replaced that air with its mass. Forget your aeronautical engineering and look to the physics. You have a closed system filled with a fluid (air) with the bird at rest its mass is supported by the structure. with the bird in flite its mass is supported by the fluid which in turn is supported by the structure. Do you hold that a body in zero gravity in the space shuttle can be discounted if that body is not in contact with the structure of the craft when the craft accelerates?
the open cockpit the void is filled with air. But in a pressurized airframe whether the bird is at rest or in flite its presence still has displaced the air equal to its volume and replaced that air with its mass. Forget your aeronautical engineering and look to the physics. You have a closed system filled with a fluid (air) with the bird at rest its mass is supported by the structure. with the bird in flite its mass is supported by the fluid which in turn is supported by the structure. Do you hold that a body in zero gravity in the space shuttle can be discounted if that body is not in contact with the structure of the craft when the craft accelerates?
flight requires moving air downward
For heavier than air flight the plane must move enough air downward to equal gravity pulling the plane downward. So a fly inside a plane is pushing air downward to fly. The air pushes against the plane's floor and there is no net change in the airplane's weight between the fly sitting or flying. The downward movementof air is often as a vortex. A small plane can crash if it flys into one of these vortexs. In flight training you are taught to fly above the vortex or a long way behind a large airplane. The vortexs are more severe as a plane slows for landing as the weight of the plane is transferred to a smaller area of air. This downward air motion is very apparent in helicopter flight. The same thing happens in our boats. You all have probably noticed the water streaming out behind your boats prop. To move forward we push water backwards. Swimming the classic dog paddle is another example of pushing a fluid down so we can go up. Ross you still miss the point that speed is distance divided by time. If you want to stop time then there is no speed because any number divided by zero is meaningless. Also if you insist that there is no movement so there is no distance then you have 0 divided by zero. Which is also meaningless. But if your car is traveling down the interstate at 65 mph your tires on average are traveling the same speed especially if you are using the hour as a unit of time. Even if your tires are spinning in the snow and ice if you reduce the time interval to zero there is no motion relative to anything. Try this experiment. Mark a point on your tire. Drive up the interstate for exactly one hour. Measure the distance that that point on your tire has traveled. It will be 65 miles if your speedometer is correct. Now if I want to know the speed of a bullet at exactly the instant it is leaving the barrel of a gun(zero time interval) I know that it is zero. Of course if I want to know the distance it travels in a second it will be about 2200' for a 22 long rifle high speed. Of course at the end of that second it will be traveling much slower.
For heavier than air flight the plane must move enough air downward to equal gravity pulling the plane downward. So a fly inside a plane is pushing air downward to fly. The air pushes against the plane's floor and there is no net change in the airplane's weight between the fly sitting or flying. The downward movementof air is often as a vortex. A small plane can crash if it flys into one of these vortexs. In flight training you are taught to fly above the vortex or a long way behind a large airplane. The vortexs are more severe as a plane slows for landing as the weight of the plane is transferred to a smaller area of air. This downward air motion is very apparent in helicopter flight. The same thing happens in our boats. You all have probably noticed the water streaming out behind your boats prop. To move forward we push water backwards. Swimming the classic dog paddle is another example of pushing a fluid down so we can go up. Ross you still miss the point that speed is distance divided by time. If you want to stop time then there is no speed because any number divided by zero is meaningless. Also if you insist that there is no movement so there is no distance then you have 0 divided by zero. Which is also meaningless. But if your car is traveling down the interstate at 65 mph your tires on average are traveling the same speed especially if you are using the hour as a unit of time. Even if your tires are spinning in the snow and ice if you reduce the time interval to zero there is no motion relative to anything. Try this experiment. Mark a point on your tire. Drive up the interstate for exactly one hour. Measure the distance that that point on your tire has traveled. It will be 65 miles if your speedometer is correct. Now if I want to know the speed of a bullet at exactly the instant it is leaving the barrel of a gun(zero time interval) I know that it is zero. Of course if I want to know the distance it travels in a second it will be about 2200' for a 22 long rifle high speed. Of course at the end of that second it will be traveling much slower.
Tom I love you like a brother but your theories
are flawed. Place a very small drop of paint on the pavement directly in front of your tire and drive across it. If there is any difference between the speed of the tire surface and the road surface the little drop of paint will be smeared. I think that you missed the point of the joke. The point at which the rubber meets the road has no speed. make a paper loop and hold it down with a finger and push it along another piece of paper, make pencil marks on the inside of the paper loop and the paper you are rolling it on. Remember the bulldozer tracks they grip the ground and do not slip. a car tire has a very short flat section where the rubber meets the road just like a bulldozer track. if you drive through a little water and then on dry pavement your tire tread prints a perfect pattern on the pavement of the tread design. The tire is indeed traveling at the speed of the vehicle but the top of the tire has to travel twice as fast as the vehicle because the tread on the road doesn't slip.
are flawed. Place a very small drop of paint on the pavement directly in front of your tire and drive across it. If there is any difference between the speed of the tire surface and the road surface the little drop of paint will be smeared. I think that you missed the point of the joke. The point at which the rubber meets the road has no speed. make a paper loop and hold it down with a finger and push it along another piece of paper, make pencil marks on the inside of the paper loop and the paper you are rolling it on. Remember the bulldozer tracks they grip the ground and do not slip. a car tire has a very short flat section where the rubber meets the road just like a bulldozer track. if you drive through a little water and then on dry pavement your tire tread prints a perfect pattern on the pavement of the tread design. The tire is indeed traveling at the speed of the vehicle but the top of the tire has to travel twice as fast as the vehicle because the tread on the road doesn't slip.
Consider the aircraft carrier
Aircraft carriers always head into the wind to cause there deck (tarmac) speed to be added to the already present true air speed. This gives the planes an added boost of airspeed when they get shot off the catapult. The real question is if an aircraft carrier is doing 10 knots against a 10 knot current and the wind is not blowing will the jet on the catapult crash or fly once it get out over the water. I believe they have a knob in the catapult control room to adjust the steam pressure of the catapult for just such occurrences.
Aircraft carriers always head into the wind to cause there deck (tarmac) speed to be added to the already present true air speed. This gives the planes an added boost of airspeed when they get shot off the catapult. The real question is if an aircraft carrier is doing 10 knots against a 10 knot current and the wind is not blowing will the jet on the catapult crash or fly once it get out over the water. I believe they have a knob in the catapult control room to adjust the steam pressure of the catapult for just such occurrences.
THE ANSWER IS NO 
IF I READ THIS TRUE boat speed is measured in the water and current is also a water measurement so no the boat is not going anywhere sorry to bust your bubble brian
IF I READ THIS TRUE boat speed is measured in the water and current is also a water measurement so no the boat is not going anywhere sorry to bust your bubble brian
Define headway
The boat does not "know" if the water is moving relative to the ground. So yes, the boat makes 10 knots headway relative to the water. If the water is moving at 10 knots in the opposite direction, the boat makes no headway relative to the ground. Lets change things just a bit: Wind is 10 knots from the North, relative to the ground. Current is 5 knots to the East, relative to the ground. What True Wind Angle and Speed will the boat's instruments display? Assume a course 45deg off the true wind (relative to the boat), and the boat can sail at 5 knots. What is the true course on each tack and what is the apparent wind speed and angle on each tack? What would the Course Over Ground and Speed Over Ground (GPS) be? *666
The boat does not "know" if the water is moving relative to the ground. So yes, the boat makes 10 knots headway relative to the water. If the water is moving at 10 knots in the opposite direction, the boat makes no headway relative to the ground. Lets change things just a bit: Wind is 10 knots from the North, relative to the ground. Current is 5 knots to the East, relative to the ground. What True Wind Angle and Speed will the boat's instruments display? Assume a course 45deg off the true wind (relative to the boat), and the boat can sail at 5 knots. What is the true course on each tack and what is the apparent wind speed and angle on each tack? What would the Course Over Ground and Speed Over Ground (GPS) be? *666
Happy Mardi Gras
While you people contemplate the laws of physics I will go watching the boat babes of New Orleans show their goods for 20 cent beads. I would post some pics but....
While you people contemplate the laws of physics I will go watching the boat babes of New Orleans show their goods for 20 cent beads. I would post some pics but....
yes
the boat will be making headway against the 10 knot current however it will not be making headway over ground. Unless you meant the boat speed was 10 knots over ground? The weight of the airplane in level flight will be the same when the fly is in level flight(does that ever happen?) but its mass will be greater with the fly than without. If the plane,air,pilot and fly could be encapsulated and then weighed on a scale, the weight would remain the same with the fly flying or not. btw i'll bet the tarmac in Corvallis is faster than the tarmac in Seattle.
the boat will be making headway against the 10 knot current however it will not be making headway over ground. Unless you meant the boat speed was 10 knots over ground? The weight of the airplane in level flight will be the same when the fly is in level flight(does that ever happen?) but its mass will be greater with the fly than without. If the plane,air,pilot and fly could be encapsulated and then weighed on a scale, the weight would remain the same with the fly flying or not. btw i'll bet the tarmac in Corvallis is faster than the tarmac in Seattle.
My Wife Wouldn't let me go to Fat Tuesday
I went alone a few years ago and she got really mad and hardly talked to me for a few weeks. I didn't know that so many women have pierced nipples!!! ouch!!! It was fun. I didn't have to drive and kept my attitude adjusted all day. We went to several parades during the day and wandered around the french quarter till about midnight. I want to go back..maybe next year. Now my wife wants me to participate in Ash Wednesday... is it fair to have to participate in Ash Wednesday without Fat Tuesday?? Ross we've about worn out the discussion on movement. It's semantics and not a paradox at all. I still have a fix from sailing Sunday. A great day with the rail almost buried. Plan to go back Saturday. The bad thing about a great day of sailing is that you go back wanting another great day. Unfortunately my experience is that a day spent near hull speed is rare. Most days it's 3-4 knots.
I went alone a few years ago and she got really mad and hardly talked to me for a few weeks. I didn't know that so many women have pierced nipples!!! ouch!!! It was fun. I didn't have to drive and kept my attitude adjusted all day. We went to several parades during the day and wandered around the french quarter till about midnight. I want to go back..maybe next year. Now my wife wants me to participate in Ash Wednesday... is it fair to have to participate in Ash Wednesday without Fat Tuesday?? Ross we've about worn out the discussion on movement. It's semantics and not a paradox at all. I still have a fix from sailing Sunday. A great day with the rail almost buried. Plan to go back Saturday. The bad thing about a great day of sailing is that you go back wanting another great day. Unfortunately my experience is that a day spent near hull speed is rare. Most days it's 3-4 knots.
Different parts of the tire...
move at different speeds, or, more precisely, different velocities. Since the tire is round (hopefully) every point on the circumference of the tire has a unique velocity in any measurable time frame. Cheers, Bob
move at different speeds, or, more precisely, different velocities. Since the tire is round (hopefully) every point on the circumference of the tire has a unique velocity in any measurable time frame. Cheers, Bob
Uncalled for
Personal attacks are uncalled for. Anyone that understands their formal education should be able to point out why the fly in the airplane and and a particle in suspension are different. The particle in suspension is not using energy to remain suspended. The fly buzzing around inside the cabin is using energy. When the fly is resting on the dash, the airplane's energy is used to support it's weight. When the fly is buzzing about, the fly's energy is supporting it. The total energy remains the same. In the case of the fly at rest, the energy is: Airplane 100% + Fly 0% = 100% In the Case of the fly buzzing about, the energy is: Airplane 99.99% + Fly 0.01% = 100% As always; F = MA. The Force needed to maintain level flight is equal to the Mass times Acceleration. In steady state level flight, the Acceleration equals the acceleration due to gravity (32ft/sec^2). Ftotal = Mtotal x A Mtotal = MAirplane + MFly Thus Ftotal = Mairplane x A + Mfly x A or Ftotal = Fairplane + Ffly No need for personal attacks to explain simple physics.
Personal attacks are uncalled for. Anyone that understands their formal education should be able to point out why the fly in the airplane and and a particle in suspension are different. The particle in suspension is not using energy to remain suspended. The fly buzzing around inside the cabin is using energy. When the fly is resting on the dash, the airplane's energy is used to support it's weight. When the fly is buzzing about, the fly's energy is supporting it. The total energy remains the same. In the case of the fly at rest, the energy is: Airplane 100% + Fly 0% = 100% In the Case of the fly buzzing about, the energy is: Airplane 99.99% + Fly 0.01% = 100% As always; F = MA. The Force needed to maintain level flight is equal to the Mass times Acceleration. In steady state level flight, the Acceleration equals the acceleration due to gravity (32ft/sec^2). Ftotal = Mtotal x A Mtotal = MAirplane + MFly Thus Ftotal = Mairplane x A + Mfly x A or Ftotal = Fairplane + Ffly No need for personal attacks to explain simple physics.
I Figured It Out!!
Let's assume that the current is moving east to west. The speed of the earth is 870.2 kt, moving east to west The speed of the current is 10 kt moving east to west The speed of the boat is 10 kt moving west to east So you add 870.2 (speed of earth) and 10 (speed of current) and subtract 10 (speed of boat) and you come up with 870.2kt. Man that's a fast boat. I should have been a mathemetician instead of a nuclear physicist. Here's a new one for you, Brian If I ascend my mast using my brand spanking new ATN Top Climber at .5 kt and the ascender gives way, assuming that the speed of gravity is 32.2 ft/s/s and I am 190 lbs., how much kinetic energy is released when I impact the deck. Don't forget to factor in the momentum of my ascent. Jack Manning s/v Victim of Fate Atlantic City, NJ
Let's assume that the current is moving east to west. The speed of the earth is 870.2 kt, moving east to west The speed of the current is 10 kt moving east to west The speed of the boat is 10 kt moving west to east So you add 870.2 (speed of earth) and 10 (speed of current) and subtract 10 (speed of boat) and you come up with 870.2kt. Man that's a fast boat. I should have been a mathemetician instead of a nuclear physicist. Here's a new one for you, Brian If I ascend my mast using my brand spanking new ATN Top Climber at .5 kt and the ascender gives way, assuming that the speed of gravity is 32.2 ft/s/s and I am 190 lbs., how much kinetic energy is released when I impact the deck. Don't forget to factor in the momentum of my ascent. Jack Manning s/v Victim of Fate Atlantic City, NJ
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