Gravitational & Inertial Mass: Why the Difference?

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In summary, the conversation discusses the distinction between gravitational mass and inertial mass and the fact that they are equal, which is not apparent in classical physics and requires explanation. The conversation also brings up the concept of acceleration not increasing gravitational mass, and the equivalence of inertial mass and gravitational mass in Einstein's "Principle of Equivalence" and General Relativity. Links are provided for further reading and a research group that tests this principle.
  • #1
JasonRox
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Why do we make such a careful distinction between gravitational mass and inertial mass, rather that talking about one mass only, since they are equivalent?
 
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  • #2
There is no apparent reason why they should be equal in classical physics. The fact that they are equal requires explanation.
 
  • #3
This is a question in the book. Practice question so it's not worth marks. I personally thought they are different, and that gravitational mass is a direct result from inertial mass.

Is that right?

Another question... I've been pondering this one.

Let's say we have they train cars. They say that the first couplings have more force exerted on them than the last one.

If they are moving at a constant velocity, and we ignore friction, would they have all equal forces of 0.

According to Newton's Laws, they will continue on forever. If one had to snap, which is impossible, it would be impossible to predict on top of that.
 
  • #4
I could be wrong about this, but I am under the impression that acceleration does not increase gravitational mass of the object, only it's inertial mass.
 
  • #5
Think about a collsion between two charged objects compared to a collison between two objects with no charge.

Pallidin in relativity the inertial mass and the gravitational mass are one in the same.
 
  • #6
jcsd said:
Think about a collsion between two charged objects compared to a collison between two objects with no charge.

Pallidin in relativity the inertial mass and the gravitational mass are one in the same.

So, the gravitational field coming from a given object is increased by acceleration? Thus, would a finely balanced, perimeter weighted gyroscope, having a rest weight of "x" actually weigh slightly more when accelerated?
 
  • #7
The equivalence of inertial mass and gravitational mass is one form of Einstein's "Principle of Equivalence", which led to General Relativity.

Here's a nice discussion
http://www.pa.uky.edu/~cvj/as500_lec6/as500_lec6.html
http://instruct1.cit.cornell.edu/courses/astro101/lec24.htm
http://csep10.phys.utk.edu/astr162/lect/cosmology/equivalence.html

Here's a research group that tests the principle
http://www.npl.washington.edu/eotwash/index.html
 
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What is the difference between gravitational and inertial mass?

Gravitational mass refers to the force experienced by an object in a gravitational field, while inertial mass refers to an object's resistance to changes in its state of motion.

Why is there a difference between gravitational and inertial mass?

The difference between gravitational and inertial mass is due to the nature of gravity, which is a fundamental force in the universe that causes objects with mass to attract each other.

How is gravitational mass measured?

Gravitational mass can be measured by observing the force of gravity acting on an object. This can be done by using a balance scale, or by measuring the acceleration of a falling object.

How is inertial mass measured?

Inertial mass can be measured by applying a known force to an object and measuring its resulting acceleration. This is known as Newton's Second Law of Motion, which states that the force applied to an object is directly proportional to its acceleration.

Why is the concept of gravitational and inertial mass important in physics?

The concept of gravitational and inertial mass is important in physics because it helps us understand the fundamental forces of the universe and how objects behave in relation to these forces. It also plays a crucial role in many equations and models used in physics, such as Newton's Laws of Motion and Einstein's Theory of General Relativity.

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