Relative Posted October 7, 2014 Author Posted October 7, 2014 (edited) And the diagram There's a decent chance that Relative is using "reaction" in that way, which is confusing because it has a specific definition within physics. A general balance of forces, equilibrium, and in the singularity diagram , this would apply to whether it was the sun or the earth has a singularity. Edited October 7, 2014 by Relative
Strange Posted October 7, 2014 Posted October 7, 2014 know what Isotropic means , the arrows represent the direction of the isotropic , I didnt need to put a load of arrows facing the same way around the sphere,, If it is isotropic, then it doesn't have a direction. A singularity, just the one mass, no other mass in the universe, a sun on itself, gravity still exists , output still exists, do you agree with the diagram? OK. That isn't what "singularity" means. But never mind, we are used to that by now... Are you asking: if there is a single mass, then gravity will produce a force towards it (equally in all directions) and potential energy will increase as you move away from it (equally in all directions) ? Then yes. (Although how you define potential energy in the absence of another mass is a problem ...)
Relative Posted October 7, 2014 Author Posted October 7, 2014 If it is isotropic, then it doesn't have a direction. OK. That isn't what "singularity" means. But never mind, we are used to that by now... Are you asking: if there is a single mass, then gravity will produce a force towards it (equally in all directions) and potential energy will output equally in all directions) ? Then yes. (Although how you define potential energy in the absence of another mass is a problem ...) I edited your wording I need to add another diagram associated with the ground pushing back , I see no push back only density? Isotropic centripetal force? Is there a Transverse square law?
Strange Posted October 7, 2014 Posted October 7, 2014 and potential energy will output equally in all directions Potential energy is not "output". It is something an object gains when lifted against gravity, for example. I need to add another diagram associated with the ground pushing back , I see no push back only density? Firstly, 9.8 m/s2 is not a force. It is an acceleration. In your diagram nothing is accelerating downwards because the force upwards from the ground equals the force of gravity downwards. I don't see where density comes into it. Density is the mass per unit volume. So s small object that weighs 1kg is denser than a large object that weighs 1kg. Is there a Transverse square law? I don't even know what that means. A square law means that one value increases by the square of the value of another. For example, the area of a circle is 9 time bigger if you increase the radius by 3 times. An inverse square law means that something decreases by the square of the value of another. For example, gravity is 9 times less if you are 3 times as far away.
Fuzzwood Posted October 7, 2014 Posted October 7, 2014 You add force to either action on the ground when it loses V and curves you do not want me to start drawing cannon balls do you? Nope, just gonna show you why you don't need to throw electronic forces to reason why we don't fall into the sun. Now assume for a minute that we remove the atmosphere and thus all friction caused by air. Let's say we are on the moon right now. Will the stone still fall at our feet when simply released and fall a bit further when it is thrown?
studiot Posted October 7, 2014 Posted October 7, 2014 (edited) A general balance of forces, equilibrium, A general balance of forces does not necessarily mean equilibrium. You need to complete your course in your Torque thread to find out more. If you must know, it is called Poinsot's Theorem. Edited October 7, 2014 by studiot
Fuzzwood Posted October 7, 2014 Posted October 7, 2014 And the diagram A general balance of forces, equilibrium, and in the singularity diagram , this would apply to whether it was the sun or the earth has a singularity. The term you are looking for is 'point mass'.
Relative Posted October 7, 2014 Author Posted October 7, 2014 Potential energy is not "output". It is something an object gains when lifted against gravity, for example. Firstly, 9.8 m/s2 is not a force. It is an acceleration. In your diagram nothing is accelerating downwards because the force upwards from the ground equals the force of gravity downwards. I don't see where density comes into it. Density is the mass per unit volume. So s small object that weighs 1kg is denser than a large object that weighs 1kg. I don't even know what that means. A square law means that one value increases by the square of the value of another. For example, the area of a circle is 9 time bigger if you increase the radius by 3 times. An inverse square law means that something decreases by the square of the value of another. For example, gravity is 9 times less if you are 3 times as far away. You are not considering that an object on the ground still a force pulling it on it equal to the acceleration of 9.81ms2, if i take way the ground the object would accelerate at that? you are also not considering that also the ground is been attracted by the earths center of gravity, the ground also is trying to accelerate at the force equal to acceleration of 9.82ms2. I drop a rock into a natural hole in the Earth and it falls at that acceleration, The ground compresses towards the center of gravity, more dense, centripetal isotropic compression of matter, following the inverse square law, but inwards rather than outwards. Yes gravity weakens square to the inverse outwards, and so does density of matter in the earth. The term you are looking for is 'point mass'. Thank you A general balance of forces does not necessarily mean equilibrium. You need to complete your course in your Torque thread to find out more. If you must know, it is called Poinsot's Theorem. Thank you and will go over to the torque thread, and look up that Theorem. Nope, just gonna show you why you don't need to throw electronic forces to reason why we don't fall into the sun. Now assume for a minute that we remove the atmosphere and thus all friction caused by air. Let's say we are on the moon right now. Will the stone still fall at our feet when simply released and fall a bit further when it is thrown? The stone on the moon will fall at our feet, however if we add horizontal force, the stone will travel further because there is less opposing force from gravity slowing it down. You are not considering that an object on the ground still a force pulling it on it equal to the acceleration of 9.81ms2, if i take way the ground the object would accelerate at that? you are also not considering that also the ground is been attracted by the earths center of gravity, the ground also is trying to accelerate at the force equal to acceleration of 9.82ms2. I drop a rock into a natural hole in the Earth and it falls at that acceleration, The ground compresses towards the center of gravity, more dense, centripetal isotropic compression of matter, following the inverse square law, but inwards rather than outwards. Yes gravity weakens square to the inverse outwards, and so does density of matter in the earth. Thank you Thank you and will go over to the torque thread, and look up that Theorem. The stone on the moon will fall at our feet, however if we add horizontal force, the stone will travel further because there is less opposing force from gravity slowing it down. Or gravity drag I call it. You are not considering that an object on the ground still a force pulling it on it equal to the acceleration of 9.81ms2, if i take way the ground the object would accelerate at that? you are also not considering that also the ground is been attracted by the earths center of gravity, the ground also is trying to accelerate at the force equal to acceleration of 9.82ms2. I drop a rock into a natural hole in the Earth and it falls at that acceleration, The ground compresses towards the center of gravity, more dense, centripetal isotropic compression of matter, following the inverse square law, but inwards rather than outwards. Yes gravity weakens square to the inverse outwards, and so does density of matter in the earth. Thank you Thank you and will go over to the torque thread, and look up that Theorem. The stone on the moon will fall at our feet, however if we add horizontal force, the stone will travel further because there is less opposing force from gravity slowing it down. Or gravity drag I call it.
swansont Posted October 7, 2014 Posted October 7, 2014 Or gravity drag I call it. Drag is yet another word that has a specific meaning in physics (and fluid dynamics) There is no drag in Fuzzwood's example. Gravity cannot exert any kind of tangential force on uniform objects, i.e. points or spheres. The forces are between the centers, and thus there is no torque.
Strange Posted October 7, 2014 Posted October 7, 2014 The stone on the moon will fall at our feet, however if we add horizontal force, the stone will travel further because there is less opposing force from gravity slowing it down. Wrong. One important thing to understand in these sort of simple examples is that (perhaps surprisingly) if you throw the rock sideways, it always has the same sideways velocity. It doesn't slow down (until it hits the ground). On the other hand, it's vertical velocity starts at zero and accelerates due to the force of gravity. This force is less on the moon so it accelerates more slowly so it takes longer to reach the ground. That is why it goes further: it has the same sideways velocity but it takes longer to reach the ground and so it can travel furtehr sideways. Does that make sense? By the way, this is all very easy to measure and confirm that things really do behave like that. (I remember doing something with cameras and strobe lights ...) So this isn't just "repeating known science" or "copying from a book" as you like to complain. You could even confirm this behaviour for yourself, if you wanted.
Relative Posted October 7, 2014 Author Posted October 7, 2014 Wrong. One important thing to understand in these sort of simple examples is that (perhaps surprisingly) if you throw the rock sideways, it always has the same sideways velocity. It doesn't slow down (until it hits the ground). On the other hand, it's vertical velocity starts at zero and accelerates due to the force of gravity. This force is less on the moon so it accelerates more slowly so it takes longer to reach the ground. That is why it goes further: it has the same sideways velocity but it takes longer to reach the ground and so it can travel furtehr sideways. Does that make sense? By the way, this is all very easy to measure and confirm that things really do behave like that. (I remember doing something with cameras and strobe lights ...) So this isn't just "repeating known science" or "copying from a book" as you like to complain. You could even confirm this behaviour for yourself, if you wanted. No it slows down or else you would not have curvature, if that were the case it would be linear and angled towards the ground, it loses V to curve, gravity curvature . I have to have velocity that has the force to escape gravity, to keep linear momentum, I fire an arrow and with a pyramid tip on , if there is not enough compensation of acceleration to gravity the arrow will instantly fall, if I give the arrow enough F, the arrow will travel linear. Only when the arrows force runs out, slowing down the arrow, and then gravity takes hold.
Fuzzwood Posted October 7, 2014 Posted October 7, 2014 (edited) The curve forms because the stone accelerates towards the ground. It doesn't start at the same vertical velocity as when it hits the ground. Contrarily, once the stone leaves my hand when on the moon, it WILL travel at the same velocity horizontally until impact as when it left my hand. The stone WILL, however, immediately start falling towards the ground when I release it. The horizontal component of the force applied has 0 effect on the vertical compound of the force. Edited October 7, 2014 by Fuzzwood
Strange Posted October 7, 2014 Posted October 7, 2014 No it slows down or else you would not have curvature, if that were the case it would be linear and angled towards the ground, it loses V to curve, gravity curvature. As I say, it is very easy to test this and find out that your intuition is wrong. That is why science works: it doesn't accept "common sense" or what "seems right". It tests it to find out what really happens.
Relative Posted October 7, 2014 Author Posted October 7, 2014 The curve forms because the stone accelerates towards the ground. It doesn't start at the same vertical velocity as when it hits the ground. Contrarily, once eythe stone leaves my hand when on the moon, it WILL travel at the same velocity horizontally until impact as when it left my hand. The stone WILL, however, immediately start falling towards the ground when I release it. The horizontal component of the force applied has 0 effect on the vertical effect of the motion. Hey?, if i continue to accelerate an object horizontal on a y axis , it continues into space, if i set the velocity of an object to V?, horizontal, it will orbit around the planet, or I can increase the v to have it fly off the planet y axis.
Strange Posted October 7, 2014 Posted October 7, 2014 In your diagram you are applying a continuous(?) force sideways and therefore the object will continue to accelerate. When you throw a ball, you give it an initial velocity and then no more force is applied horizontally. Therefore it carries on at the same speed horizontally. Meanwhile, completely independently, it accelerates downwards.
swansont Posted October 7, 2014 Posted October 7, 2014 No it slows down or else you would not have curvature, if that were the case it would be linear and angled towards the ground, it loses V to curve, gravity curvature . I have to have velocity that has the force to escape gravity, to keep linear momentum, I fire an arrow and with a pyramid tip on , if there is not enough compensation of acceleration to gravity the arrow will instantly fall, if I give the arrow enough F, the arrow will travel linear. Only when the arrows force runs out, slowing down the arrow, and then gravity takes hold. This is absolutely NOT how it works. There are a multitude of misconceptions. (All of which are addressed by taking a physics class) Gravity is always working in such an example, and the travel of such an arrow is never linear. It will follow a ballistic trajectory — a parabolic arc. In the absence of air resistance, the speed will not change in the horizontal direction, because there is no force in that direction.
studiot Posted October 7, 2014 Posted October 7, 2014 Gravity is always working in such an example, and the travel of such an arrow is never linear. It will follow a ballistic trajectory — a parabolic arc. In the absence of air resistance, the speed will not change in the horizontal direction, because there is no force in that direction. Just to clarify something for you. It is implied in what is being said about horizontal that posters are approximating the Earth (or Moon) to a flat surface in the region where the stone is being thrown sideways and that a horizontal line is a straight line at right angles to the vertical at the point of projection. Of course in reality the surface of the Earth etc is curved, not flat and a truly horizontal line is a curved line that follows this curve.
Strange Posted October 7, 2014 Posted October 7, 2014 Here is a plot of how a thrown object falls. The dots are 1 second apart. In this example, it is thrown with a horizontal velocity of 10m/s. See how it moves 10 m horizontally in each second. But see how the distance it falls vertically increases each second because it is accelerating.
Relative Posted October 8, 2014 Author Posted October 8, 2014 (edited) ''In your diagram you are applying a continuous(?) force sideways and therefore the object will continue to accelerate.''YES When you throw a ball, you give it an initial velocity, yes, and then no more force is applied horizontally.YES Therefore it carries on at the same speed horizontally. NOMeanwhile, completely independently, it accelerates downwards.'' Not quite From an instant an arrow is launched it starts to lose energy of the force applied on the arrow from the Bow and the arm pulling the string back, Before the launch, both the bow and the arrow are been attracted by gravity, the force of gravity is already acting on the arrow, from launch , gravity is still attracting the arrow , although the flight is horizontal , G still attracts the arrow, the force is always down, even when horizontal and at maximum velocity, the gravity drags on the arrow, hence what I call gravity drag, the force of the drag taking out the velocity of the arrow slowing it down, eventually the tip drops and then the curve occurs. Fire an arrow vertically , and watch it slow, then eventually a pyramid tip, will flip 180 and return to you. And the net force is zero to the moon? ''The Moon has an external magnetic field that is very weak in comparison to that of the Earth'' The moons magnetic field is not a magnetic field , that you consider a magnetic field, the moons magnetic field is because by electrostatics , the moon absorbs electrons from the sun, it is charged, well maybe? And the moons equilibrium is now offset been repelled by the earth, Here is a plot of how a thrown object falls. The dots are 1 second apart. In this example, it is thrown with a horizontal velocity of 10m/s. See how it moves 10 m horizontally in each second. But see how the distance it falls vertically increases each second because it is accelerating. Clipboard01.png I understand that but if the velocity drops it does the same thing Edited October 8, 2014 by Relative
Strange Posted October 8, 2014 Posted October 8, 2014 Therefore it carries on at the same speed horizontally. NOMeanwhile, completely independently, it accelerates downwards.'' Not quite As I say, it is very easy to check this. Those of us who have done it know that you are just making baseless assertions here. And the net force is zero to the moon? Obviously not, or it would fly away in a straight line. The moons magnetic field is not a magnetic field And it really is made of cheese.
swansont Posted October 8, 2014 Posted October 8, 2014 From an instant an arrow is launched it starts to lose energy of the force applied on the arrow from the Bow and the arm pulling the string back, Before the launch, both the bow and the arrow are been attracted by gravity, the force of gravity is already acting on the arrow, from launch , gravity is still attracting the arrow , although the flight is horizontal , G still attracts the arrow, the force is always down, even when horizontal and at maximum velocity, the gravity drags on the arrow, hence what I call gravity drag, the force of the drag taking out the velocity of the arrow slowing it down, eventually the tip drops and then the curve occurs. At no point is the flight actually horizontal, though the deflection angle is small at the beginning when the downward velocity is small. The force of gravity cannot change the horizontal velocity of the arrow, since the two are perpendicular. Fire an arrow vertically , and watch it slow, then eventually a pyramid tip, will flip 180 and return to you. Any evidence this has ever happened with a normal arrow?
Fuzzwood Posted October 8, 2014 Posted October 8, 2014 When you throw a ball, you give it an initial velocity, yes, and then no more force is applied horizontally.YES Therefore it carries on at the same speed horizontally. NO <-- YES
Strange Posted October 8, 2014 Posted October 8, 2014 When you throw a ball, you give it an initial velocity, yes, and then no more force is applied horizontally.YES Therefore it carries on at the same speed horizontally. NO <-- YES Bigger letters: you win! (Oh yeah. That and the evidence.)
Relative Posted October 8, 2014 Author Posted October 8, 2014 (edited) Bigger letters: you win! (Oh yeah. That and the evidence.) Evidence- force decreases over distance, it slows down F=ma , You get shot by an arrow at 50 yrds, and I will stand 1000yrds Edited October 8, 2014 by Relative
andrewcellini Posted October 8, 2014 Posted October 8, 2014 Evidence- force decreases over distance, it slows down F=ma , what force?
Recommended Posts