If anti-gravity is possible?
If anti-gravity is possible?
yes Anti-gravity is an idea of creating a place or object that is free from the force of gravity. It does not refer to the lack of weight under gravity experienced in free fall or orbit, or to balancing the force of gravity with some other force, such as electromagnetism or aerodynamic lift
In simple terms Anti-gravity is generating a counter to Newton's law of gravity F=GmM/r^2. The properties of anti-gravity are: um
- The strength of force should be proportational to mass the product of the mass of the objects
- It should be a repulsive force
- The force should drop off an inverse distance square law
- The potential energy generated by the force should be proportional to the distance.
- It should work in a vacuum.
Nowhere does it say these "EXACT" rules are needed. So we could be flexible on some so long as it has the net effect desired. For example, I'm sure we would consider a force that dropped off more slowly than the inverse square distance law a suitable source of anti-gravity if it met the other criteria.
What you are seeing in the above picture is a super conductor suspending a magnet. Impressive, almost magical. But as impressive as it looks, it only meets criteria 2 out of 5 criterias to be considered anti-gravity. It is repulsive and works in a vacuum.
There is another common force that seems to meet these criteria:
If you guessed normal force you are correct. Thanks to the Pauli exclusion princible, two objects cannot occupy same state. This creates a force that prevents the book on the table from falling through the table into the floor. If the table is flat compared to the ground the table is not moving relative to the Earth, and the only other force on the block is gravity, then the normal force will exactly counter the force of gravity. A table on the moon works as well as one on Earth. So at first it actually seems to meet all the criteria to be anti-gravity. The strength of the force is proportational to the mass of the object, the force is repulsive, and as you move the table through space, the normal force on the block drops off with an inverse square law.
What are we missing? Potential energy. The normal force is based purely on the distance from the table. If the block is on the table it feels the force. If it is not, it doesn't. There is no potential energy associated with this force. To lift an object with the normal force, you have to supply all the work needed to lift both the block and the table. Or in the case of an elevator, you need to supply all the work to lift both the elevator and the occupants.
So sadly, a normal force seems like anti-gravity, but it isn't.
Another one that seems like anti-gravity:
If you guessed buoyancy, you are correct. Like the normal force, at first buoyancy seems to meet all the criteria. However the force is not determined by the mass of the balloon, but the net mass the balloon displaces, and buoyancy does not work in a vacuum. With increasingly large balloons buoyancy works in a very near vacuum, so in many cases this is a suitable substitute for true anti-gravity.
Anti-gravity is an idea of creating a place or object that is free from the force of gravity. It does not refer to the lack of weight under gravity experienced in free fall or orbit, or to balancing the force of gravity with some other force, such as electromagnetism or aerodynamic lift
In simple terms Anti-gravity is generating a counter to Newton's law of gravity F=GmM/r^2. The properties of anti-gravity are: um
- The strength of force should be proportational to mass the product of the mass of the objects
- It should be a repulsive force
- The force should drop off an inverse distance square law
- The potential energy generated by the force should be proportional to the distance.
- It should work in a vacuum.
Nowhere does it say these "EXACT" rules are needed. So we could be flexible on some so long as it has the net effect desired. For example, I'm sure we would consider a force that dropped off more slowly than the inverse square distance law a suitable source of anti-gravity if it met the other criteria.
What you are seeing in the above picture is a super conductor suspending a magnet. Impressive, almost magical. But as impressive as it looks, it only meets criteria 2 out of 5 criterias to be considered anti-gravity. It is repulsive and works in a vacuum.
There is another common force that seems to meet these criteria:
If you guessed normal force you are correct. Thanks to the Pauli exclusion princible, two objects cannot occupy same state. This creates a force that prevents the book on the table from falling through the table into the floor. If the table is flat compared to the ground the table is not moving relative to the Earth, and the only other force on the block is gravity, then the normal force will exactly counter the force of gravity. A table on the moon works as well as one on Earth. So at first it actually seems to meet all the criteria to be anti-gravity. The strength of the force is proportational to the mass of the object, the force is repulsive, and as you move the table through space, the normal force on the block drops off with an inverse square law.
What are we missing? Potential energy. The normal force is based purely on the distance from the table. If the block is on the table it feels the force. If it is not, it doesn't. There is no potential energy associated with this force. To lift an object with the normal force, you have to supply all the work needed to lift both the block and the table. Or in the case of an elevator, you need to supply all the work to lift both the elevator and the occupants.
So sadly, a normal force seems like anti-gravity, but it isn't.
Another one that seems like anti-gravity:
If you guessed buoyancy, you are correct. Like the normal force, at first buoyancy seems to meet all the criteria. However the force is not determined by the mass of the balloon, but the net mass the balloon displaces, and buoyancy does not work in a vacuum. With increasingly large balloons buoyancy works in a very near vacuum, so in many cases this is a suitable substitute for true anti-gravity.
