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. D

    How to find the center of mass of a cube?

    Homework Statement Find the center of mass of a homogeneous solid cube with side ##L## analytically. Homework Equations None. The Attempt at a Solution I don't understand how to find the center of mass on three dimensions. I know that since it is homogeneous, if I center the cube on the...
  2. D

    Find the center of mass of a plate

    Homework Statement Find the center of mass of the next plate if: A) Is homogeneous B) Its density per unit mass is ##\sigma=Axy##, where ##A## is a constant. Homework Equations ##X_{cm}=\frac{\int\sigma x dA}{\int\sigma dA}## ##Y_{cm}=\frac{\int\sigma y dA}{\int\sigma dA}## The Attempt at a...
  3. F

    Maximum displacement in mass spring system

    Homework Statement A block is suspended by an ideal spring of the force constant K. If the block is pulled down by applying a constant force F and if maximum displacement of the block from its initial position of rest is X then, find the value of X. Homework Equations mg + F = XK + K(mg/K)...
  4. osten

    Oscillation Problem -- Ball mass on the end of a horizontal spring

    Homework Statement A 200 g ball attached to a spring with spring constant 2.40 N/m oscillates horizontally on a frictionless table. Its velocity is 20.0 cm/s when x=−5.00cm. What is the amplitude of oscillation? Homework Equations f=√(k/m) /2π x(t) = Acos(2πft) v(t) = -2πfAsin(2πft) The...
  5. A

    Mass hanging from a 2-pulley system

    Homework Statement I have a question about the pulley problem in the attachment. Homework Equations This question can be answered using equilibrium of forces, namely Fx = 0 and Fy = 0. The Attempt at a Solution The answer key states that for the sum of the x-components, we should use the...
  6. C

    About initial mass function and mean mass in stellar cluster

    Homework Statement Assuming a Salpeter IMF with upper and lower mass limits of 0.1 and 20 M⊙ respectively, calculate: (i) the mass point at which half the mass formed in a stellar cluster lies in more massive systems and half in less massive systems. ii) the mass point at which half the...
  7. J

    Finding Ctr of Mass of object w/ given uniform mass density

    Homework Statement Find the Center of Mass locations of a thin stick of mass M and length L, whose left ends are at x=0. The stick has uniform mass density λ1 = 2M/3L along the left half, and has uniform mass density λ2 = 4M/3L along the right half. Homework Equations I know that this is...
  8. S

    I Phonon Mass: Understanding its Sign and Effects on Gravity

    What is the sign of phonon mass? A substance of uniform composition, in a field of gravity, has pressure increasing downwards. This causes the compressibility to decrease downwards - and speed of sound to increase downwards. In a gradient of downwards increasing velocity, a wave propagating...
  9. J

    Finding the POSITION of the center of mass

    Homework Statement Three spheres are placed around a coordinate grid: one of mass m at the bottom-left, one of mass 3m a distance of 3L above the first, and one of mass 2m a distance of 4L to the right of the first. 4 points between these three spheres are labeled: A near (1.3L, 1.5L), B...
  10. Arturas Surblys

    How strong should an electromagnet be to elevate a 1kg mass?

    Hello Everybody, Can somebody help me to find out about Electromagnets and Electric motors? I hope that here it is possible to get an expert opinion about the next question. How strong should be electromagnet to elevate and hold f.e. 1 kg weight in the middle of a ferrous environment (f.e. cube...
  11. H

    Effect of the Location of the Center of Mass on the Falling Time....

    The set-up of the system is like the following: The thing is, a weight was attached to the meter stick and it was placed in different locations. Then the system composed of the meter-stick and the added weight was then released and the time it took for the meter stick to hit the floor was...
  12. nineteen

    Chemistry Finding the Chemical Formula and Relative Molecular Mass

    My chemistry teacher gave me this problem. I tried and tried, but I couldn't figure it out and the deadline is tomorrow. Please help me out here friends. 1. This is the problem : In a compound which is made of element Y, weight percentage of Y is 72% and N( Nitrogen) is 28%. Also, 3 Y atoms...
  13. E

    A variable mass problem with friction

    Homework Statement A water tank with a total mass of m0 is moving on a horizontal road with a coefficient of friction equals to μ. At t=0 water starts to come out of the tank with a velocity equal to u0 in relation to the tank. Each second the mass of water that comes out is λ. Find the...
  14. E

    Why Is Momentum Conserved in a Variable Mass System Like a Sand-Laden Cart?

    Homework Statement A cart with no motor moves on a plane. At t=0 it has a mass equal to m0 and some velocity. Each second sand with a mass of α comes out of the cart with a velocity of 0 in relation to the plane. What is the equation of motion of the cart? Answer: dV/dt=αv(t)/(m0-αt) Homework...
  15. J

    Diving Board Torque with No Mass Given For the Diver

    The board is 4m and has 2 supports: support 1 exerts 5400N and support 2 exerts 6000N before the diver performs the dive. Neglecting the mass of the board, what is the force on the board due to the weight of the diver? My attempt at this question: FS2 - FS1 = 6000 - 5400 = 600N But I'm having...
  16. E

    Where is my mistake? (Pure rolling and center of mass)

    Homework Statement A cylinder with a mass of M and radius R is attached to a spring with a constant of k. The attachment always stays the same as described in the picture. The cylinder is moved to the right and the released, and it rolls without slipping (pure rolling). What will be the...
  17. M

    Twin spring system with a mass in between (X and Y direction)

    Hello my fellow scientists! This is my first post on this forum, but most certainly not my last. I am relatively new to physics. I mean, i understand the basics. I would like to make it my hobby. You know, really find a passion for the physics. BTW, i am from the Netherlands, so please do not...
  18. A

    B Understanding gravity: mass and gravity relation

    << Mentor Note -- thread moved from the Introductions forum to the technical forums >> Hello there, This is my first post, I find myself often wondering about the universe and how it works, and there are a couple of things I just can't wrap my head around. According to wikipedia the force that...
  19. J

    Automotive Torque formula to throw a mass with two pulleys and a belt

    Hey guys What's is the formula to find the force(torque) to throw a mass in the air that is 500kg/m(3) with 2 pulley and a belt. Thanks
  20. Robin04

    Density function, calculating the mass

    Homework Statement The density of a rod in function of space is given as ##\rho (x)=\frac{c}{x^2}## 1. What kind of density is this? 2. What is the dimension of ##c##? 3. What is the mass of the rod in the intervals - [1 m, 2 m], - (1 m, 2 m), - (0 m, 1 m), - [0 m, 1 m]? 4. Can a plate with...
  21. NotSoRobot

    Newton's Laws Homework question: Double incline mass problem

    Homework Statement I have a double incline mass problem where Φ=43° and θ=20°, mass_A=1.00kg and they are connected by a massless string where the net force of each block is equal to 0. Homework Equations I believe I am to use Newton's 2nd law to find the force of the tension which I have next...
  22. S

    I Relativistic mass and gravitational potential

    Hello everyone, Any object has a gravitational potential energy as a function of the distance from the Earth (R). Does this energy depend only on the rest mass of the object; or one must take into account it's relativistic mass? In other words, if we imagine two identical bullets on the top...
  23. Edge5

    Force felt by the accelerometer in a smartphone

    My smartphone has an accelerometer inside it. Does the phone itself and the proof mass of the accelerometer feel the same acceleration OR do they feel the same force, when I apply a force to my phone? I think they feel the same acceleration, F=ma. Force felt by proof mass and the force felt by...
  24. L

    Question About the Escape Velocity from Different Mass Planets

    Hi! I have a question about escape velocity. If a planet is bigger and have a greater escape velocity than another planet. Do this effect the density of the bigger planet in any way? Or do we have to know the mass of the bigger planet to know if the density is larger or lower for this planet?
  25. Arman777

    B Naked Singularity, Black hole mass limit

    I came across a question on PSE. I am not sure its a violation to ask the same question here, but there's no answer to the question in there so I wanted to ask it here. Quoting his question,"Since the universe has a positive cosmological constant, there is an upper limit on the mass of the...
  26. J

    with this tension problem -- Mass on an accelerating cable

    Homework Statement A 35 kg mass is being raised by a cable with decreasing speed. At the instant the upward velocity has a magnitude of 1.6 m/s and the downward acceleration has magnitude of 1.2 m/s2, what is the tension of the cable? m=35 kg v=1.6 m/s a= -1.2 m/s2 g= 9.81 m/s2 Homework...
  27. Buckethead

    B Presentation of mass as a physical quantity

    I have started hosting a "scence open mic" and the first one last month was very successful so I'm doing it again. We had about 30 people show up and 5 presenters including myself giving up to an 18 minute talk on anything science. It was a great experience and I encourage others to try it in...
  28. G

    Modeling a mass hanging by a spring: motion in 3D time/freq domain

    Hello everyone, I am new here, and wondering if anyone would have some knowledge on a current problem I have been working on. I am trying to create time- and frequency domain 3D models of an object hanging using a spring from a fixed point within a shell. I am trying to figure out how the...
  29. dani546237

    Thrust 6.05MN, mass 4,520,000 lbm, what is the acceleration?

    if the first stage provides a thrust of 6.05 mega-Newtons [MN] and the space shuttle has a mass of 4,520,000 pound-mass [lb Subscript m], what is the acceleration of the spacecraft in miles per hour squared [mi divided by h squared]? Equation: F=ma conversions: 1000m=0.621mi 3600s=1 hour I'm...
  30. Leonardo Machado

    I Energy Density & Mass Density: Explained

    Hi everyone! I'm currently strudying some astrophysical equation of states, some stuff about Fermi's gas and I'm kinda confused about the relation between the energy density and the mass density, $$ \frac{\epsilon}{c^2}=\rho. $$ I don't get why they do not use whole $$...
  31. Jeviah

    Spring characteristics when loaded with a mass

    Homework Statement If a spring is loaded with a mass, the spring being completely vertical and the mass hanging below it there would be an extension in the spring relative to the mass applied/force applied according to hookes law. If the same spring was not vertical but coiled (similar to a...
  32. R

    Mass Balance Approach for a 2-Stage Distillation Problem

    Homework Statement 180kmol/hr of a three component mixture made up of 60 mol % A, 25 mol % B and 15 mol %. Component A is the most volatile ,component C is the least volatile. The mixture is to be passed through a 2 stage distillation process. 80% of component C leaves the bottom of the first...
  33. Antony Death

    B Is the current definition of gravity accurate?

    The current definition of Gravity is: The force of attraction between bodies as a result of their mass. Gravity affects both the space and time of the area surrounding a mass, diminishing with distance, so is the current accepted definition truly accurate? Do I have the correct definition and if...
  34. CrosisBH

    Mass of Ice required to achieve a certain final Temperature

    Homework Statement An insulated beaker with negligible mass contains a mass of 0.350 kg of water at a temperature of 76.5 °C. How many kilograms of ice at a temperature of − 23.9 ∘C must be dropped in the water to make the final temperature of the system 40.0 ∘C? Take the specific heat for...
  35. D

    Secondary ions entering a mass filter in Secondary Ion Mass Sprectrometry (SIMS)

    Hello, I have a question about secondary ions entering a mass filter in Secondary Ion Mass Sprectrometry (SIMS). We know that secondary ions are sputtered from surface of studied sample. Those secondary ions are entering a mass filter which sort them out due to their mass/charge ratio. After...
  36. K

    Problem when calculating the center of mass of a triangle

    Homework Statement if the black dot is assumed by (0,0).find the center of mass coordinate of this triangle [/B] i'm sorry but since the pic won't show ill attach the link here https://ibb.co/4Ptw5T7 <Moderator's note: picture added> Homework Equations centroid is 2/3 of median [/B] using...
  37. B

    Calculate rest mass given relative speed and kinetic energy?

    The answer is 3.079*10^-26 kg I tried doing E=mc^2 20*10^9*1.602*10^-19=m*(3*10^8)^2 m=3.56*10^-26 kg However when I do E=γmc^2 I get the correct answer. Is the question wrong, because isn't it 20 GeV of kinetic energy, not total energy?
  38. P

    Calculating the mass and price of LPG needed to heat water

    Hello everyone, Homework Statement How many kilograms of lpg will you use if you heat 5 litres of water from 20C to 90C everyday for 30 days and how much will that cost if a 12.5kg cylinder is 1750 Rupees The attempt at a solution To heat 1 liter of water by 1C requires 4.18kJ so you then...
  39. 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...
  40. Levi Woods

    I How Do I Calculate the Mass of a Planet Using a Simulation?

    I'm having trouble with this simulation I was given by my teacher, any help with how I should go about this?https://www.thephysicsaviary.com/Physics/APPrograms/MassOfPlanet/index.html
  41. S

    B Do Black holes reach a critical mass?

    Are there any theories on Blackholes becoming so massive that the forces generated by the matter within them exceeds the forces compressing them and the tipping point leads to a Big Bang?
  42. Justin71

    Inertial force acceleration (vertical axis)

    Hi, How is the inertial force Fi (acceleration) when the system is vertical. I noted Fi_horizontal=m.a, Ff=mg.μ.cos(Θ) et Fg=mg.sin(Θ) .
  43. Hiero

    Torque about center of mass due to Coriolis force, is it 0?

    It’s essentially a question about cross product identities. I want to analyze a problem in a frame of reference which is rotating with angular velocity ##\vec \Omega## relative to an inertial frame. In this non-inertial frame, we have a rigid body rotating with constant angular velocity ##\vec...
  44. jybe

    Mass launched into the air by a spring

    Homework Statement A child's toy consists of a piece of plastic attached to a spring in the figure below. The spring is compressed against the floor a distance of 2.00 cm, and the toy is released. If the toy has a mass of 117 g and rises to a maximum height of 45.0 cm, estimate the force...
  45. A

    I Calculate mass from time dilation

    Based on the exponential growth of time dilation 0.0 - 1.0 if given the radius of an object how do you calculate the mass of the object? Time dilation is a function of gravity. Which can be thought of as escape velocity from a gravitational field. So if you have to achieve .866 c to escape...
  46. Louis Nardozi

    I What is the mass of all photons emitted in the universe?

    What is the mass of all photons emitted in the universe since the Big Bang?
  47. M

    Find the Mass of the Candy Knowing the Total Mass of the Bags

    [Mentors' note: There's no template because this thread was moved from General Physics. The specification of the problem seems adequate without the template] Hi everyone, I am working through stuff based on the Millikan Oil Drop experiment. There is a question that asks to determine the mass...
  48. T

    Spring and mass with varying force -- what is the change in temperature?

    Homework Statement A system consists of a mass m moving in one dimension and attached to a rigid wall by a spring having stiffness constant ##K##, as shown. The mass is subjected to a constant force ##F##, and is in equilibrium with the surroundings at a temperature ##T##. The partition...
  49. Physics Dad

    Finding an expression for the total mass of a star

    I have made an attempt at the question below and just wanted to check if my thinking was correct or totally wrong. Thank you in advance! 1. Homework Statement In a simple model of a star, the density is described as ρ=ρ0(1-r/R), where R is the stellar radius, and ρ0 is the central density...
  50. Z

    Do Photons Have Mass?

    Does a photon have mass?
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