what dries faster, hot or cold water?
General Discussion: The late crew - night thread - Physics thread
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6 Sep 2006 19:19
6 Sep 2006 20:00
Sorry i find this hard to accept, I dont think you would stop dead, your flying ffs, just because your wheels are on a converyor belt all of a sudden should not effect your momentum airspeed?
Its a teaser, i mean if your moving forward in the air, but if the ground you touch is in effect moving against at the same speed are you moving?
6 Sep 2006 20:22
6 Sep 2006 20:55
i think it would fly as the energy is not being forced form the ground up, as in the wheels are not the source of power.
wings work by the movement of air under the, to cause a pressure difference, it would not fly.
the power lies within the engines which have no connection to the travelling ground.
They are conencted to the whole body which is connected to the ground through the wheels
so wouldnt the plane just roll over the ground as the force is generated from the wings to push the weight from on top of the wheels to behind???
the engine thrust is a horizontal force in parallel with the ground, it attempts to push the plane forward but it cannot as the floor is moving the other way.
also on a side note, if you let a bird loose on a plane say the plane is big enough for it fly aorund in, would it eventually be drawn to the back of the plane?
No, every object in the plane is subjected to the same forces, the air everything, just becasue its floating doen't mean it doesn't feel the force. This how sounds works…
or better yet, an open top bus, if you throw a ball in the air on the bottom floor it will go in a stright vertical line.
if you thrown the ball up in a vertical line say 5 feet on top of the bus, how far will it go back, if at all.
Straight up. you are travellign forward so is the ball, when you release it it already has the same horizontal speed as yourself hence it goes up and down…
if you're sitting at the back of the bus on the top open deck and throw the ball forward but diaginally upwards, can you throw it hard enough with the right amount of speed for it land in your lap????
only if the bus suddenly acceralated while the ball was in the air, the force on the ball when you release has x, when you trown it forward it has x+5 for example, the bus would have to acceralate faster to get to atleast x+5 speed for that to work, this is unlikely or course.
wings work by the movement of air under the, to cause a pressure difference, it would not fly.
the power lies within the engines which have no connection to the travelling ground.
They are conencted to the whole body which is connected to the ground through the wheels
so wouldnt the plane just roll over the ground as the force is generated from the wings to push the weight from on top of the wheels to behind???
the engine thrust is a horizontal force in parallel with the ground, it attempts to push the plane forward but it cannot as the floor is moving the other way.
also on a side note, if you let a bird loose on a plane say the plane is big enough for it fly aorund in, would it eventually be drawn to the back of the plane?
No, every object in the plane is subjected to the same forces, the air everything, just becasue its floating doen't mean it doesn't feel the force. This how sounds works…
or better yet, an open top bus, if you throw a ball in the air on the bottom floor it will go in a stright vertical line.
if you thrown the ball up in a vertical line say 5 feet on top of the bus, how far will it go back, if at all.
Straight up. you are travellign forward so is the ball, when you release it it already has the same horizontal speed as yourself hence it goes up and down…
if you're sitting at the back of the bus on the top open deck and throw the ball forward but diaginally upwards, can you throw it hard enough with the right amount of speed for it land in your lap????
only if the bus suddenly acceralated while the ball was in the air, the force on the ball when you release has x, when you trown it forward it has x+5 for example, the bus would have to acceralate faster to get to atleast x+5 speed for that to work, this is unlikely or course.
Ok the read mill is moving in the opposite way to your movement. Put a stationary object onto it, it sticks to it the travels in the direction of the treadmill. Its energy is absorbed by friction in the horizontal and by the treadmill pushing back up on it in the vertical. Becasue it sticks it then travels in the direction of the treamill, the wall is the deacceralting force the treadmill applies to the object to get it to stop then stick (in combination with friction) obviosuly with a wheeled device friction is less as the wheels spin.
As the plane lands normally it has a speed say constant 100mph the ground applies a force vertical to stop the plane sinking inot the floor and friction on the wheels slows it down. The rate of negative accelartion is small, so hence the force felt by the plane . passengers is small.
you feel a bump upwards but you are not pinned in your seat on landing like you are on take off, this is horizontal not vertical force.
If the runway was a treadmill, you would feel the force like when you break hard in a car, that is becasue the ground is now producing a horizontal force to slow the plane down, if the speed was the same, it would deaccerate the plane from high speed to low speed very quickly.
By F = ma with m and a being very large you have a massive force on the plane, hence the wall effect.
Crashing the car inot a wall is the same type of rapid deacceration.
As the plane lands normally it has a speed say constant 100mph the ground applies a force vertical to stop the plane sinking inot the floor and friction on the wheels slows it down. The rate of negative accelartion is small, so hence the force felt by the plane . passengers is small.
you feel a bump upwards but you are not pinned in your seat on landing like you are on take off, this is horizontal not vertical force.
If the runway was a treadmill, you would feel the force like when you break hard in a car, that is becasue the ground is now producing a horizontal force to slow the plane down, if the speed was the same, it would deaccerate the plane from high speed to low speed very quickly.
By F = ma with m and a being very large you have a massive force on the plane, hence the wall effect.
Crashing the car inot a wall is the same type of rapid deacceration.
Sorry i find this hard to accept, I dont think you would stop dead, your flying ffs, just because your wheels are on a converyor belt all of a sudden should not effect your momentum airspeed?
Its a teaser, i mean if your moving forward in the air, but if the ground you touch is in effect moving against at the same speed are you moving?
If the wheels can take the force entirely then its like two moving cars hitting each other at exactly the same speed, if they were exactly eqaul mass the would both stop dead against each other (assuming they are indestructable)
Ignore the medium adn object, you are just talkign about vector forces colliding, i have simplied it to a 2 dimension description.
A wall , someone running inot you, a moving floor are all things that slow you down by appling force int he opposite direction as long as one point contacts with it the force is applied to the object.
The transferance of force i am describing is perfect, as the wheels and tread mill ar enot perfect it would skid forward a bit before stopping, but it would stop significantly quicker than just a normal runway.
Ignore the medium adn object, you are just talkign about vector forces colliding, i have simplied it to a 2 dimension description.
A wall , someone running inot you, a moving floor are all things that slow you down by appling force int he opposite direction as long as one point contacts with it the force is applied to the object.
The transferance of force i am describing is perfect, as the wheels and tread mill ar enot perfect it would skid forward a bit before stopping, but it would stop significantly quicker than just a normal runway.
but why would it skid if the conveyer belt is moving at an equal speed to the object, but at the same time the ground speed is irrelevent as the plane is travleling in the air, just because its wheels touch the ground makes no odds does it? I dont know, carnt get my head around it, dont worry.
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