- #1
johann1301
- 217
- 1
According to wikipedia, «inertia is the resistance of any physical object to a change in its state of motion or rest, or the tendency of an object to resist any change in its motion.»
To explain what i think the common misunderstanding of inertia is, one finds it helpfull to talk about matter without inertia.
Mass with- and without inertia:
If I were to talk about matter without the property of inertia, I would be talking about an unobserved object. In other words; Matter without inertia does not really exist(or very unknown). Yet it is important to stress that a hypothetical object without inertia, would also keep its original state of motion when not-forced-upon, just as an object with inertia would. At least hypothetically.
The difference lies in the amount of force needed to move the objects. An object without inertia - no matter how big or small it is - would need a force of zero Newton(no force) to change its state of motion. In the case where the object has inertia(wich is the realistic case), the amount of force would vary proporsional with the objects mass. (this is a known fact). If the mass is bigger, the inertia is bigger. (and vica versa)
If this hypothetical presumtion is true, it would imply that inertia (not matter) is the reason why a force is needed to move an object.
For example: You get shot by a pistol. If the bullet has no inertia, you would not feel the bullet hitting you.
To explain even further; the period where an object goes from beeing in one state of motion A to another state of motion B, is the timeframe where inertia plays its role. This is the period were one observes resistance. In the case were inertia does not exist, there would be no resistance in this period. In any other time then between A and B, no-inertia and inertia would be the same thing.
These postulates about inertia are therefore misleading:
1. An object at rest tends to stay at rest.
2. An object in motion tends to stay in motion.
Source: http://www.qrg.northwestern.edu/projects/vss/docs/Propulsion/2-what-is-inertia.html
These are well known statements about inertia, but they do not mention anything about resistance.(at least not directly) These statements imply that objects stay in motion and rest becouse of inertia. As described earlier, this shouldn't be the true. They stay at rest and in-motion becouse nothing is acting on it. This leeds to another question...
What makes objects move?
In the example where the non-inertial bullet hits you without you feeling it, the bullet also stops!
Inertia shouldent stop objects, in fact it is known to resist any change of motion. There is no logic then, in that a non-inertial bullet should act any different. Inertia has therefore nothing to do with why objects change their state of motion or change shape. That must be explained by something else.
There are probably many explenations why an object can change its shape or state of motion. The Pauli exclusion principle is perhaps one of the explenations or our general idea of friction.
anyway...
Are there other people who agree with me?
Is saying «An object at rest tends to stay at rest» the same as saying that «An object tends to resist any change in its motion»?
i think not...
To explain what i think the common misunderstanding of inertia is, one finds it helpfull to talk about matter without inertia.
Mass with- and without inertia:
If I were to talk about matter without the property of inertia, I would be talking about an unobserved object. In other words; Matter without inertia does not really exist(or very unknown). Yet it is important to stress that a hypothetical object without inertia, would also keep its original state of motion when not-forced-upon, just as an object with inertia would. At least hypothetically.
The difference lies in the amount of force needed to move the objects. An object without inertia - no matter how big or small it is - would need a force of zero Newton(no force) to change its state of motion. In the case where the object has inertia(wich is the realistic case), the amount of force would vary proporsional with the objects mass. (this is a known fact). If the mass is bigger, the inertia is bigger. (and vica versa)
If this hypothetical presumtion is true, it would imply that inertia (not matter) is the reason why a force is needed to move an object.
For example: You get shot by a pistol. If the bullet has no inertia, you would not feel the bullet hitting you.
To explain even further; the period where an object goes from beeing in one state of motion A to another state of motion B, is the timeframe where inertia plays its role. This is the period were one observes resistance. In the case were inertia does not exist, there would be no resistance in this period. In any other time then between A and B, no-inertia and inertia would be the same thing.
These postulates about inertia are therefore misleading:
1. An object at rest tends to stay at rest.
2. An object in motion tends to stay in motion.
Source: http://www.qrg.northwestern.edu/projects/vss/docs/Propulsion/2-what-is-inertia.html
These are well known statements about inertia, but they do not mention anything about resistance.(at least not directly) These statements imply that objects stay in motion and rest becouse of inertia. As described earlier, this shouldn't be the true. They stay at rest and in-motion becouse nothing is acting on it. This leeds to another question...
What makes objects move?
In the example where the non-inertial bullet hits you without you feeling it, the bullet also stops!
Inertia shouldent stop objects, in fact it is known to resist any change of motion. There is no logic then, in that a non-inertial bullet should act any different. Inertia has therefore nothing to do with why objects change their state of motion or change shape. That must be explained by something else.
There are probably many explenations why an object can change its shape or state of motion. The Pauli exclusion principle is perhaps one of the explenations or our general idea of friction.
anyway...
Are there other people who agree with me?
Is saying «An object at rest tends to stay at rest» the same as saying that «An object tends to resist any change in its motion»?
i think not...