What is Inertial mass: Definition and 47 Discussions

Mass is both a property of a physical body and a measure of its resistance to acceleration (rate of change of velocity with respect to time) when a net force is applied. An object's mass also determines the strength of its gravitational attraction to other bodies.
The SI base unit of mass is the kilogram (kg). In physics, mass is not the same as weight, even though mass is often determined by measuring the object's weight using a spring scale, rather than balance scale comparing it directly with known masses. An object on the Moon would weigh less than it does on Earth because of the lower gravity, but it would still have the same mass. This is because weight is a force, while mass is the property that (along with gravity) determines the strength of this force.

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  1. KnightTheConqueror

    B Inertial Mass vs Gravitational Mass

    Why does the text saying that the Newton's framework doesn't require the two masses to be equal? If using f = ma give us inertial mass then how is f = Gm1m2/r² a different things? Isn't the law defined as the force is directionly proportional to the product of the masses and we calculated the...
  2. dom_quixote

    B Tangran, Inertial Mass and Gravitational Mass

    Imagine a tangran puzzle, in which an extra piece "y", identical to piece 'x', is maliciously added. No matter how hard the player tries, he will never be able to restore the game's original form, that is: a perfect square. This illustration has a clear purpose: If gravitational mass and...
  3. W

    I Energy Density in E Field: Does it Contribute to Inertial Mass?

    Hi. I'm not sure where to put this question, it concerns particles, mass-energy equivalence and various things. Classical electromagnetism seems to be as sensible a place as any. There is energy stored in an E field. Energy density (at position r, time t) = \frac{1}{2}...
  4. J

    B Gravitational Mass of C/2 Objects: Jim Adrian's Inquiry

    I would like to be sure that objects passing at high speed (half or more of the speed of light) have more gravitational attraction to each other than they would if their relative speed were forty miles per hour. Thank you for your help. Jim Adrian
  5. T

    I The existence of negative gravitational plus positive inertial mass?

    The term “negative mass” gets puts forth occasionally, and it’s definitions can sometimes be unclear. the topic I’m interested in is particles which have both positive inertial mass and negative gravitational mass. So far, what theories do physicists have of speculating on the existence of...
  6. M

    I Inertial Mass as Speedometer: Physics & Universe

    I get that the concept of relativistic mass has sort of been deprecated in physics these days and that relativistic momentum is supposed to be seen as more well useful. So let momentum equal ##\mathtt ~~ \frac {mv} {\sqrt {1 - \frac {v^2} {c^2}}} ~~## or ##~~{mv\gamma}~~##. So mass is supposed...
  7. M

    Find the fractional increase in inertial mass when an ice cube melts

    Summary: Apparently an ice cube gains mass when it melts So I'm asked to "Find the fractional increase in inertial mass when an ice cube melts ". All I've got off the top of my head right now is that a cube has energy = mc^2, and then when the cube melts, energy Q = (Heat of fusion)(m) is...
  8. TerranIV

    I Particles w/ 0 Inertial Mass Traveling Faster than Light?

    I was just curious if there were any known (theoretical) particles with zero inertial mass that don't travel at light speed. Is this even possible?
  9. H

    I Any direct evidence of gravitational mass increase?

    Is there any evidence that objects moving increasingly closer to light speed gain gravitational mass, in the sense of attracting surrounding (and not co-moving) masses more strongly, rather than solely possessing the increased inertial mass implied by the greater force necessary to...
  10. Lee Sung Bin

    B Relativistic Physics: Gravitational & Inertial Mass

    In Newtonian mechanics, both gravitational mass and inertial mass is m. This principle is known as the principle of equivalence. However, I heard that in Relativity, gravitational mass is γm instead of m because total energy of the particle is γmc2. But in special relativity, it is widely known...
  11. Jan Nebec

    I Can we deal with relativistic mass once and for all?

    Hello! I've been reading about relativistic mass for last few days and it leads me to even more confusion. Supposing, we are assuming SR. 1. Why some people say that relativistic mass leads to confusion? As far as I learned, relativistic mass tells me the mass of an object, that is moving...
  12. T

    I How to prove gravitational mass & inertial mass equivalence?

    There is a video on YouTube where Sean Carroll says for Newton it was just an accident that inertial mass equals gravitational mass, but with the general theory of relativity it became obvious that it has to be so. How does one see that? My own attempt has been consisting of transforming...
  13. N

    Is Charge Equivalent to Inertial Mass?

    I've read about the equivalence between inertial mass and gravitational mass. But i can't undestand why is gravity more special then other kinds of force. I mean, why isn't charge equivalent to inertial mass? After all charge plays the same kind of role of gravitational mass in another context.
  14. S

    Potential Energy in a molecule

    Homework Statement Potential energy in a molecule[/B] (b) The figure below shows all of the quantized energies (bound states) for one of these molecules. The energy for each state is given on the graph, in electron-volts (1 eV = 1.6 ✕ 10-19 J). What is the minimum amount of energy required to...
  15. N

    Quantifying Inertial Resistance

    Hi! I am having a little trouble with a question asked by a colleague. There’s a ball B with a certain mass M, at rest. A small ball A of mass m is moving with speed v toward M. If m=M, and the collision is perfectly elastic and the two objects perfectly rigid, than we know that A would come...
  16. C

    Conceptual difference between gravitational and inertial mas

    I know that this question has been asked many times before on this forum, but on every existing thread either the question or the answers, or both, were too vague. I understand that inertial mass is defined as the property of an object to resist change of its velocity, that is the mass that...
  17. T

    What is the effect of heat on the inertial mass of a body?

    I mean, a body with higher temperature has higher energy so is it heavier than before? We know from e=m*c^2 that energy is equivalent to mass
  18. davidbenari

    Does kinetic energy increase the inertial mass?

    In class we had a conceptual problem: There will be a race between two springs. Both will receive the same initial impulse, but one has been agitated and is therefore oscillating in some way, the other is just still. Who arrives first? The answer is that the still spring arrives first because...
  19. A

    Gravitational or inertial mass gain in cern ?

    Hi, I have been reading about CERN for a while and found amazing - amongst many other things - the fact that hadrons in the LHC turn some of their energy to mass after having reached the maximum possible speed. However this statement was not clear enough. I was wondering whether the mass they...
  20. R

    Reason for separate concepts of gravitational vs inertial mass

    My mechanics prof today said when setting GMm/r2 = ma, the canceling of the small m is actually a bit nuanced because you have to assume the gravitational mass is equal to the inertial mass (though it's supported by experiments). I'm so used to seeing mass as just mass so I'm having a bit of...
  21. C

    Difference between gravitational and inertial mass

    I can't seem to get my head around the difference between the two. Inertial mass appears in F=ma and is a measure of an object's resistance to acceleration when being acted upom by a force/s. Gravitational mass appears in F=(GmM)/r^2 - what 'role' does mass play here?
  22. J

    The concept of inertial mass from Newton to Einstein

    The most common definition of mass, at least in the Newtonian context, is in terms of a measure of inertia: The mass of an object is a measure of, and gives rise to, its resistance to changes in motion. F=MA presumably quantifies this idea of inertial mass. I'm wondering whether any...
  23. R

    Inertial Mass vs. Gravitational Mass

    An interesting idea that my physics teacher posed to us yesterday, and apparently one that scientists have been puzzling over for quite a while: why is the mass as a measure of inertia equal to the mass in terms of gravity in our universe? My teacher said that this doesn't need to be the case...
  24. G

    Relation between binding energy and inertial mass

    This question has been bugging me for a while now. I roughly understand how the Higgs mechanism gives elementary particles their rest mass and I also understand that gravity couples to all forms of energy, including binding energy in a nucleus or atom. I also know most of the mass of a system...
  25. G

    Is the inertial mass of light relative?

    By the equivalence principle, the gravitational mass of light is its inertial mass, which it has because it has momentum. Light can impart some of its the momentum to massive objects, upon which it will lose energy, which is manifested by its frequency (the basic principle behind doppler...
  26. F

    Do the electrons have inertial mass?

    Hello there! According to quantum physics, do the electrons have inertial mass? I read somewhere electrons were an amount of energy, with no mass at all. I think I'm confused about the concept of "mass" since I know two, the one they taught me at school, which I'm considering as inertial mass...
  27. K

    Why is inertial mass not an observable in QM?

    In classical mechanics, I can measure the inertial mass of a particle by measuring force and acceleration: m=F/a. In QM, this equation only holds for expectation values <F> and <a>. Does this lead to the fact that inertial mass is not an observable? Is there a deeper underlying principle which...
  28. L

    Calculate INERTIAL MASS of proton traveling close to speed of light

    Homework Statement A proton is traveling with a speed of v = 2.993x108 m/s. Calculate the value of the inertial mass for this proton. Assume that the speed of light is c = 3.000 x 108 m/s and that the mass of the proton is 1.673 x 10-27 kg. Note: Do your calculations to 4 significant...
  29. N

    Gravitational mass vs inertial mass

    In Sean Carroll's lecture book is written: "... if gravitation did not couple to itself, a "gravitation atom" (two particles bounded by their mutual gravitational attraction) would have a different intertial mass (due to negative binding energy) than gravitational mass..." Would you please...
  30. T

    Inertial mass, gravitational mass, and the Higgs

    If we explain the origin of inertial mass with the Higgs mechanism, how do we explain the origin of gravitational mass? In other words, how does the Higgs mechanism contribute to the gravitational field of a particle? (Note: the closest thread I've found to this is...
  31. T

    What Drives the Mass of Particles According to Theoretical Physics?

    A favourite - good grief no. I don’t even understand some of the Higgsless models. I’m not a theoretical physicist. For one thing, my maths isn’t up to it. No, it’s more of an unease with the Standard Model, even though the Standard Model has good agreement between experiment and theory in the...
  32. T

    Exploring Inertial Mass and Time Travel Possibilities

    No pitchforks please (and lay off the caps with the big 'D' on them too) Following staying up until 4am (all good stories start like this), and making small talk with a friend doing a degree in physics, we both decided to harp on about theoretical theories such as string etc, and as hours...
  33. N

    Gravitational vs Inertial Mass

    (I realized I have a confusing post title but can't figure how to edit it..It should read "Gravitational curvature vs gravitational force" Under 'mass' Wikipedia makes a statement:
  34. R

    Gravitational force = inertial mass

    I am not trained in physics but find it extremely interesting to read about. As I was reading a book on Einstein it talked about about gravitational force being equal to inertial mass. A good deal of the discussion talked about a man in a box and the inability to distinguish one effect from...
  35. K

    Is inertial mass of gas the same as its rest mass

    Suppose we have a box at rest that is filled with a uniform gas. We denote the volume by V and the pressure by p. Suppose next that we apply a small force to the box and accelerate it until it has a speed v. The key question is: Is it harder to accelerate the gas because it takes work not only...
  36. S

    Why is gravitational mass the same as inertial mass?

    Gravitational mass is the property of objects that determines how they interact via gravity. For example how the Moon rotates around Earth. Inertial mass is an object's property that determines how much the object "resists" acceleration when force is applied to it. And it seems both are...
  37. L

    What are the standard units for inertial mass and gravitational mass?

    [SOLVED] What are the standard units for inertial mass and gravitational mass? 1. What are the standard units for inertial mass and gravitational mass? And also apparently gravitational mass can be measured without gravity how can it be done? Thank you very much. My teacher said a hint is in...
  38. E

    Sundance preons twists as a higgless source of inertial mass

    Currently, the standard explanation for inertial mass is the higgs field, which gives particles their mass. Many of the SM's undefined parameters involve interactions between the particles and the higgs field, as well as the mass of the higgs boson itself. Sundance preon braiding has twists...
  39. N

    Gravitational Charge - Equivalence between Gravitational and Inertial Mass

    Gravitational "Charge" - Equivalence between Gravitational and Inertial Mass My mind is currently in a mess regarding the equivalence of gravitational mass and inertial mass. Yes, I know which comes in which equation and that they have been experimentally observed to be equal, etc., but I'm...
  40. P

    Gravitational and inertial mass

    In physics as a general discipline, there are 2 types of mass gravitational and inertial which have different definitions but experimentally they have turned to be extremely similar, 1 part in 10^12. Moreoever, general relativity predicts they are equivalent. They are all measured by an observer...
  41. L

    Gravitational mass & inertial mass

    Hey, first time here. I'm currently reading up on Physics, preparing for a selection test by myself. I need some help in understanding Newton's gravitational mass and inertial mass. Are they different? I read that there are some difference, and these masses ARE slightly different. Any reason...
  42. S

    Measuring Inertial Mass: Force, Acceleration and Mass

    I was wondering, how is it that scientists measure inertial mass. I presume they use F=ma, and thus the mass of an object would be measured by applying a force on an object and finding out the resulting acceleration. Getting acceleration is simple, but how can they measure the force? Then if...
  43. P

    Inertial mass, invariant mass and the photon?

    In some cases, inertial mass does not equal invariant mass? What is the relation between the two? So the photon can have non zero inertial mass but always 0 invariant mass?
  44. S

    What if inertial mass did NOT = grav. mass?

    What if inertial mass did NOT equal gravitational mass? How would our normal daily existence be different? Most interesting and creative answer wins ! [Edit: This is intended to be a fun question to answer, but I'm hoping to learn something quite serious from it. The force of...
  45. I

    Inertial Mass Propulsion? Feedback wanted.

    I have had this idea in my head for years and I want to know once and for all if it will work or not. I understand that a flywheel gains in mass when it spins. If this is true, is my thinking below correct? Any feedback would be appreciated! Inertial Mass Propulsion: I am going to try to...
  46. F

    Lab on measuring the inertial mass

    Ok we just did a lab on measuring the inertial mass. This is going to be really hard for me to explain but i'll try. Anyways here's the problem the gravitation masses are given to us.The are 100g, 200g, 300g and 400g. We also have to use ticker tape and we ended up finding the acceleration by...
  47. P

    Inertial mass of a stressed body

    I was wondering if anyone out there knows how to do Exercise 5.4 on page 159 of "Gravitation," by Misner, Thorne and Wheeler? It goes like this - let d^jk = Kronecker delta Consider a stressed medium in motion with ordinary velocity |v|<<1 with respect to a specific Lorentz frame (a) Show...