Mass Definition and 1000 Threads

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. Dale

    I What is the meaning of the mass assigned to an individual quark?

    A hydrogen atom is less massive than the sum of an unbound proton and an unbound electron. If I add energy to the atom the system becomes more massive, and when I add enough then I have an unbound electron and proton, each of which has the usual mass. So the mass of an electron is the unbound...
  2. draikens

    Chemistry Molar Mass Calc: My Solution | PDF File

    pdf file is my solooution l think its wrong
  3. kaycha

    Complex motion equation (projectile with changing mass and thrust)

    I need an equation to predict the flight path of a changing mass projectile under changing thrust. Any thoughts?
  4. L

    Chemistry How Accurate Should Experimental Data Be?

    Aldehyde + H2 = alcohol Ethanal + H2 = ethanol This is all that I have done so far
  5. B

    Engineering Gyroscopic Precession - Mass of wheel & Angular Momentum

    Hello, I have this i am learning. I have been trying to find information online but have struggled to find anything which helps me. YouTube usually has good videos, but doesn't seem to on this. This is one topic i have never learned before. But keen to. I was hoping someone could help me...
  6. J

    Are There Any Alternative Brass Weight Sets for Lab Equipment?

    For the past 8 years I have used weight sets like the one below and they have been very versatile. But, just before Christmas, most of them were stolen. The person was nice enough to leave me some of the 100g and below masses. I've finally gotten permission to get new sets and now I can't find...
  7. Leo Liu

    Why do objects always rotate about their centre of mass?

    Why do unconstrained objects always rotate about the lines passing through their CMs when tangential forces are applied to them? I understand that if an object does not rotate about its CM, then its rotation will decay to the rotation about the axis passing through its CM. Also, when a roller...
  8. 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
  9. ttesss

    Newton's 2nd Law: Force, Mass and Acceleration

    I´m currently studying Newtons 2nd law and I don't get how can force only depend on mass and acceleration and not on velocity.. I mean, if I punch something with my fist going at constant velocity ( acceleration=0) it stills has a force right?
  10. George2020

    The relationship between friction and mass

    Mass is directly proportional to static and kinetic friction and inversely proportion to the coefficient of friction. Material affects the coefficient of friction as well as both static and kinetic friction. eg rough surface will have a higher coeffieiceint of friction
  11. Amirul96

    Mass and Volumetric Flow rate of Natural Gas

    Hi. I am currently doing my internship in the oil and gas industry (contractor) as process engineer. My supervisor give me a task to do some reverse engineering where i need to study how a spreadsheet (calculation) construct by other process engineer was been constructed. Ok the situation is the...
  12. J

    Chemistry Calculating the Mass of a Precipitate

    Hi there, I have a problem from an exam which I passed recently, however this was one problem I got wrong and I want to understand how to solve the thing. Now I shall detail the problem below. This is my subsequent attempt to solve it after the exam (so I don't know if this attempt is correct...
  13. S

    Center of mass energy for two relativistic colliding particles

    Starting from the center of mass energy S = (E_{1} + E_{2})^2 - (\vec{p_1}+\vec{p_2}) knowing that E^2 = m_{0}c^4 + p^2*c^2 one has S = (E_{1} + E_{2})^2 - (\vec{p_1}+\vec{p_2}) = ( m_{0}c^4 + p_{1}^2*c^2) + m_{0}c^4 + p_{2}^2*c^2)^2 - p_{1}^2 - p_{2}^2 - 2p_{1}p_{2}cos \{theta} and then...
  14. T

    What I do not understand about mass spectrometers

    I try to do my assignment which is based on mass spectrometer entirely. The mass spectrometer i am working on has these parts below: 1.Accelerator region 2.Velocity selector region 3.Spectrometer The elements i am working on are isotopes of the same element and they all enter the accelerator...
  15. astroYEEET

    Mass, luminosity and magnitude of a galaxy

    So i first calculated the angular area of the galaxy. a=22.6'' and a/b=0.85 => b = 26.588''( btw I do not know why a/b =0.85 since b is the semi minor axis). Then the area of the elipse is a*b*π =1887.745''. Then using the first equation we get an apparent magnitude of m=16.511. Using the second...
  16. G

    I Why does nothing happen at the Planck mass?

    It appears as clear to me that the Planck mass has a fundamental role, since for it the deBroglie wavelength and the Schwarzschild radius are equal. So it is some borderline between elementary particles and black holes. What intrigues me, however, is that the universe is mostly made up of...
  17. Islam Hassan

    I Mass & Radiation 3D Distribution in the Universe

    What percentage of the universe’s A) total mass —including dark matter— and B) radiation energy is estimated to reside in: Inter-galactic space covering i) inter-galactic medium and ii) distinct inter-galactic astronomical objects; and Galaxies covering iii) inter-stellar gas clouds, iv) stars...
  18. R

    B How the role of Mass is justified for below cases? (Earth/Moon, Jupiter/Io)

    How the role of Mass justified for the above cases in Newton's gravitation laws & in Einstein's GR?
  19. ElectronicTeaCup

    How can I calculate work done when raising a mass using W = 32r^2?

    I do not understand how to get ##W = 32r^2##
  20. J

    Static equilibrium: mass on beam

    A diagram of the physical situation is below: Choosing the positive ##y## direction to be upwards and the positive direction of rotation to be counterclockwise, Newton's linear second law gives: $$-m_D g + F_L + F_R = 0$$ where ##F_L## is the magnitude of the force exerted on the bar by the...
  21. R

    Mass spectrometer with a Lead element

    Summary:: How to load the plates with the Lead element in the spectrometer I have a mass spectrometer with lead element which has an electronic configuration 1s^2 2s^2 2p^6 3s^2 3p^6 3d^10 4s^2 4p^6 4d^10 5s^2 5p^6 4f^14 5d^10 6s^2 6p^2. It has 2 free electron, so the ejected electrons go...
  22. S

    Do photons, phonons and electrons have mass?

    These articles have energy but do they have mass?
  23. Arman777

    A N-body simulation with varying neutrino mass

    I am trying to find a picture of the N-body simulations that shows the LSS. Particularly I am looking for different neutrino masses without the CDM. For instance pictures likes this But with more varying/different neutrino masses. I am looking for articles
  24. person_random_normal

    I Visualizing the Fourier transform using the center of mass concept

    I found this video on youtube which is trying to explain Fourier transform using the center of mass concept At 15:20 the expression of the x coordinate is given in the video. I believe it is wrong, and it should be: ##\frac{{\int g(t)e^{(-2 \pi ift)}.g(t).2 \pi f.dt}} { \int g(t).2 \pi...
  25. Y

    Moment of inertia where mass and torque are at a different positions

    The formula for moment of inertia is: I=mr^2 A common derivation for this is: 1. F=ma 2. τ=rma 3. τ=rmrα = r^2 mα This is a rotational version of Newton’s second law, where torque replaces force, moment of inertia replaces mass, and angular acceleration replaces tangential acceleration...
  26. K

    Cantilever beam deflection with point mass and point load at the end

    Hi all, I was looking for help with obtaining deflection at end of a cantilever beam with point load at end as well as point mass at the same location. I believe it would be exactly same. Is this correct? That is, I think just adding point mass at the cantilever's end wouldn't change the...
  27. LCSphysicist

    Find the period of a pendulum consisting of a disk of mass M

    I did the first step pretty well, and the answers match, but i don't understand why in the second case the period changes.
  28. J

    Chemistry Find the mass of one element of a sample

    1 mole of K2CrO4 has formula mass of ((2 x K) + (1 x Cr) + (4 x O)) g => ((2 x 39.0983) + (1 x 51.9961) + (4 x 15.9994)) g = 194.1903 g we have 2 moles of K in 1 mole of K2CrO4 = (2x 39.0983) g = 78.1966 g so for 1 mole of substance we have 78.1966 g So how many moles of the substance do we...
  29. jamiebean

    A mass being pushed up an inclined plane

    i tried to solve the problem with the above way then i calculated Fg= mass x 9.8 = 242.06 N FgII= Fg x sin50 =185.4287N so the force required is 185. is this correct?
  30. S

    New amplitude of a spring-mass system when a 2nd mass falls on the first

    I am confused about conservation of momentum for this question. I take the system as two objects, each having mass m. For first object (the one performing simple harmonic motion), there is net external force acting on it in horizontal direction (restoring force of spring). For second object...
  31. Den tredje

    A mass collides with a stick and they stick together....

    (Note: the stick weight is 0.4kg not 1.0kg) Im not a native English speaker. So please excuse my bad english. I had this on my exam, and Ím really unsure what the answer to this is. Ím suppose to calculate the hight and angle of the swing Of this stick after a “stuck together” collition. But...
  32. N

    Proving that mass is an additive quantity

    I already have referred to the solution to this problem. But the way I originally solved the problem is completely different from how the available solution proceeds. I wish to know if my solution is right or wrong. My Solution: Consider three particles undergoing one-dimensional motion all...
  33. E

    Can anyone explain this derivation of the variable mass equation?

    This question stems from one of the recent homework threads. I'm familiar with the derivation given here regarding mass accretion and ejection, where the general idea is to define a system around body and all of the incoming/leaving mass so that we can once again apply NII to the whole thing. I...
  34. D

    How Does a Variable Mass Affect a Simple Pendulum?

    Hello, I've got to rationally analice the form of the solutions for the equations of motion of a simple pendulum with a varying mass hanging from its thread of length ##l## (being this length constant). I approached this with lagrangian mechanics, asumming the positive ##y## direction is...
  35. dcheme7373

    Is There a Maximum Mass Limit for Black Holes?

    The question, "why didn't the emerging universe collapse into a black hole" has been answered in other forums. Though I am not sure I understand the reason. But it got me thinking. Is it particularly stupid to ponder whether a black hole has a maximum possible mass? Or rather a certain mass...
  36. T

    Spring: does it have mass or is it massless?

    I can easily do the second problem if only I knew the answer to the first. I am just not sure how I would go about figuring out if the spring has mass or not. And if it does, how would I calculate that mass?
  37. cheekyhouidini

    Mass of water given only power and density

    Cannot figure out where to start, apart from maybe something to do with specific heat capacity of water?
  38. S

    Distance traveled and period of a mass - spring - pulley system

    1. How will the motion of M be? I assume wire S is inelastic so will M move downwards but not in straight line? (I mean M moves downwards but because the left side of pulley is connected to S, it will be static and the right side of pulley can go down along the extension of the spring so its...
  39. C

    Graphing a spring mass collision with a wall

    Hi, I'm looking for help making a graph/model for evaluating the "bounce" of a mass behind a spring that collides with a wall. The setup would include one simple spring mass system that is attached to a wall, and another wall which is closer to the mass than the spring's free length. The mass is...
  40. E

    B The Missing Mass of a reaction

    Wikipedia says this about the missing mass of a reaction: I wondered where such an expression is coming from? The invariant mass of a system ##M##, in natural units, satisfies $$M^2 = \left(\sum E \right)^2 - ||\sum \mathbf{p}||^2$$ If anything, then the "missing" mass (which they also...
  41. mcastillo356

    Question about the quotient of the charge and mass of an electron

    hello Witch of these are certain sentences? a-\dfrac{e}{m_e}>\dfrac{H^{-}}{m_{H^{-}}}\cdot{1000} b-\dfrac{e}{m_e}>\dfrac{H^{+}}{m_{H^{+}}}\cdot{1000} The first accurate measurement of e/m was made by english physicist J.J. Thomson in 1897, who demostrated that the quotient charge-mass of the...
  42. DarkMattrHole

    I Mass distribution behavior of the singularities during black hole mergers

    When two BHs collide the resulting single BH bulges and contorts until it settles down to a stable state. 1) Does this mean that during this 'settling' period the mass internal to the merged BH is not (yet) a singularity, but instead two 'singularities' spinning down around each other in...
  43. P

    Find the tension in the string of this two mass system

    I know that it will probably execute something similar to circular motion. I thought of conserving momentum but I think there is an external force being applied due to the impulse which will prevent me from doing so. I know that once I find the tension it would become very easy to find the...
  44. C

    Using Effective Mass to find the accelerations of 3 masses connected by pulleys

    Since 2nd pulley accelerates downward with the same acceleration of m1, and because the string around pulley has a constant length, it must be that a2=−a1+ar and a3=−a1−ar, where ar is the relative acceleration between the pulley and m2. From the above 4 equations, we are supposed to determine...
  45. LCSphysicist

    Question about potential energy as a mass approaches infinity

    I was thinking, what would be the consequence if we wouldn't adopt the ro in the infinite, and i conclude that it would just irritate the accounts, with one constant more, am i right? Once what matter is the diference between the U, and no the U infact.
  46. S

    Refrigerant - mass flow, power, COP

    This is a past exam Q, I don't have the attached pressure enthalpy diagram. Q = 120kW Cp = Refrigerant enthalpy = I've looked this up, for ammonia enthalpy = 35.06 kJ / mol T2 = 5 degrees C = (5 deg C) (1100 kPa/300 kPa) = 18.33 deg C +273.15 K = 291.48 K T1 = 2 degrees C = (2 deg C)(1100...
  47. harry_thawne

    What is the relationship between mass and weight?

    What does it mean that the relationship between mass and weight is constant and proportional? I think I don't get it yet. The weight depends of mass, but at the same time depends of gravity, so if mass increase, the weight so does. But if we're on Earth we know that"g" has a value, therefore...
  48. Physics Dad

    How Accurate is the Initial Mass Function in Predicting Stellar Distributions?

    Assumptions: 1) The minimum stellar mass in this cluster is 0.1M⊙ 2) The maximum stellar mass in this cluster is 150⊙ First calculate the local stellar density constant (ξ0) for this cluster using eq 1: Having rearranged this equation and using the limits of the minimum and maximum stellar...
  49. D

    Not sure if I have the correct angle and mass for this sum of forces

    Balance the forces east-west: 3.5kg*sin45º + 4.2kg*cos30º - 4.8kg*sin30º - E*cosΘ = 0 E*cosΘ = 3.712 kg balance north-south: 2.8kg + 3.5kg*cos45º - 4.2kg*sin30º - 4.8kg*cos30º + E*sinΘ = 0 E*sinΘ = 0.982 EsinΘ / EcosΘ = 0.982 / 3.712 tanΘ = 0.2645 Θ = 14.8º ◄ E = 3.712kg / cos14.8º = 3.84...
  50. Adesh

    Oscillation of a boat in still water (Metacenter and Center of Mass)

    Let’s say we have a boat whose longitudinal axis is the y-axis (which goes into the screen in the figure below) standing upright in a still water . ##S## is the Center of Mass of the boat and ##C## is the Center of Mass of the displaced water.On ##S## lies the force ##\mathbf W##...
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