Hot answers tagged

9

The mass always means the same thing – but in different theories, one uses different equations and other tools to express the mass. Inertial mass $m$ is the quantity expressing "resistance of the object with respect to acceleration", i.e. the coefficient that enters Newton's $F=ma$. The gravitational mass is what enters the formula for the gravitational ...


7

Particle physics has a set of elementary particles , some of which have zero mass. In this table the general public has heard of the electron and maybe the photon. The mass of the electron has been measured consistent with classical definition of mass. The mathematical theory of elementary particles is called the standard model and the table has the ...


5

The term "mass" is an intrinsic property anf any body, and doesn't depend on external factors. The term "weight" is a force, i.e. it measures how much a mass is accelerated. Your mass is $m = 65\,\mathrm{kg}$. Your weight on Earth, which accelerates you at $g = 9.8\,\mathrm{m}\,\mathrm{s}^{-2}$, is $$ w \equiv mg = 65\,\mathrm{kg}\times ...


4

You are totally correct! Yes, velocity is relative, and therefore "relativistic mass" $m = \gamma ~m_0$ is relative: different people see different values. However, here's the crucial part, anyone who sees you travelling at speed $v$ with mass $m$ agrees on this number $m_0 = m / \gamma$. It is what's called a "Lorentz scalar": every coordinate system ...


4

In classical electrodynamics, assuming a point charge to be having a finite charge, the net electrostatic self energy carried by it is given by $$ Self Energy = 1/2 \int E^2 dV$$ Upon performing the intergral in three dimensions, since the electric field of a point charge diverges at the origin, therefore the rest mass by the virtue of the electrostatic ...


2

I'll reduce your question to its simplest expression: "What is mass?" And give you my best, simplest answer:"It is a measurement of how much an entity opposes acceleration or deceleration". I believe that in the end it all comes to that...


2

The experiment involves sticking the tines of the forks into the cork so that the long heavy handles of the forks extend downward. Take a look at the photo in this link: https://www.kecksci.claremont.edu/physics/demo/corkfork.htm. Now, the cork and the forks are bound together as one object, and the center of mass of that object is down toward the middle ...


2

Do we feel less weight on surface of Mount Everest? (Or have I mixed some wrong values?) The answer to both of these questions is "yes". One would weight a tiny bit less on Mount Everest, but not as much less as the question poses. You have used some incorrect values and assumptions. If you use the numbers you yourself used to compute the gravitational ...


2

Mass doesn't depend on time. As in your equation, if the difference in time increases or decreases, the difference in velocity will increase or decrease, so the mass will be constant. As velocity is a variable you cannot come to a conclusion like that. To get a proportional relationship all the other factors should be constant on the equation.


2

If I understand what the book pretends to show, the theory identified by the existence of $X^{\mu}(\tau)$ in an Lorentz-Poincaré symmetric spacetime can construct physical scalars only by some functionality of $\dot{X}^{\mu}\dot{X}_{\mu}$. The $\dot{}=d/d\tau$ came from the translations in space-time and the product $A_{\mu}B^{\mu}=g_{\mu\nu}A^{\mu}B^{\nu}$, ...


2

Mass affects the acceleration through $f=ma$, The higher the mass, the lower the acceleration for a given force. Drag is not affected by mass, only by the speed and the density of the atmosphere. Mass never ceases to influence the rocket's behaviour. Any change in speed or direction (i.e. any change in velocity) is affected by mass through the above ...


2

This link summarizes the measurements of the speed of light. The first measurement of c that didn't make use of the heavens was by Armand Fizeau in 1849. He used a beam of light reflected from a mirror 8 km away. The beam was aimed at the teeth of a rapidly spinning wheel. The speed of the wheel was increased until its motion was such that the light's ...


1

With some prior measurements such as total mass, volume of lower and upper body. I think you can use these techniques to figure the mass of just lower body. Computerized Tomography (CT) and Magnetic Resonance Imaging (MRI) These two imaging techniques are now considered to be the most accurate methods for measuring tissue, organ, and whole-body fat mass as ...


1

Simple questions are good questions, and often do not have simple answers. Gravity will always effect your rocket, although if you're far away enough from the gravity's source it may be negligible (not noticeable to you). So how far is "enough"? It depends on your limit of precision. Suppose you were making a trip that took 10 days, and you wanted to get ...


1

Here's a hint, We know $I=MR^2$ (considering point mass) from the axis of rotation where $R$ is the perpendicular distance from axis of rotation. Since each point mass is moving with a constant velocity in the same direction, it means that perpendicular distance from axis of rotation remains same. So you can calculate moment of inertia of each point mass ...


1

The value of velocity depends on the observer. Therefore the value of $\gamma$ depends on the observer. Therefore (since the value of $m_0$ does not depend on the observer) the value of $m=\gamma m_0$ depends on the observer. It's not entirely clear what's confusing you, but you appear to be assuming that $m$ should be observer-independent. It's not. ...


1

No, you're not right. The container with more mass on the right will weight more on the scale. Pressure always acts normal to a surface, and the pressure forces acting on the slanted walls of the container will have downward components, which exert net downward forces on the container. You must include these downward forces in the force balance on the ...


1

When the particle is stationary in your frame, the mass you observe is the rest mass.


1

As the definition of "rest mass", when the item is relatively static in your frame, the mass you observed is the rest mass.


1

One electron-volt $=1.6 \times 10^{-19} joules$ and is a unit of energy that is equal to the energy acquired by an electron falling across a 1 volt potential difference. The particle (neutrino) doesn't need a charge to have some energy. Instead of expressing the mass of a particle in kg, we can express it as $mc^2$ which is an energy (joules or eV... your ...


1

Although the eV is defined with respect to a particle of unit charge (an electron) in an electric field, it is simply a unit of energy. There are simple relations between thr eV and everyday units of energy, such as the Joule or calorie. Thus energies of all sorts of things, in fact any energy, can be expressed in eV, even if it has nothing whatsoever to ...


1

It is true that the heavier plane needs a greater lift and this is seen in practice. If two planes at equal altitude loose power at the same time and one weighs more than the other they will be able to glide the ...... same distance! One of them descends faster than the other but it glides forward faster to generates more lift. It seems odd, but one ...


1

The things I learnt in years of pinewood derby racing: use the maximum weight keep it at the back make sure the car tracks straight focus on stability The weight is your "engine". Since you start at a slope, mass at the back has further to drop than mass at the front (really!). You can think about it like this: if the weight of the car is evenly ...



Only top voted, non community-wiki answers of a minimum length are eligible