Mass Definition and 1000 Threads

Hi, I found this interesting thread, https://www.physicsforums.com/threads/accelerating-a-car-including-the-moment-of-inertia-of-the-wheels.930374/ but as it has been closed to replies, I decided to ask here. The thread ended up with the equation: where τ - 200Nm engine torque provided on...

For this problem, For part(a) the solution is, However, how did they know that the max speed is reached in the vertical position? For part (d) the solution is, However, I thought the solution would be because there is net gravitational torque in clockwise direction (torque due to small mass...

The block starts to slide if friction can no longer hold the block. F=u*n and F=(m1+m2)a so: (m1+m2)a=uN=>am1+am2=uN=>am2=(uN)/(am1) So:am2=(uN)/(am1) is the force. The answer is F=(u*m1g(m1+m2))/m2 I do not see how the acceleration terms are canceled. Is my answer equivalent to this?

Observational evidence for cosmological coupling of black holes and its implications for an astrophysical source of dark energy Comments?

Hi, I am not sure if I have derived the matrix correctly, because of my results in task b I solved task 1 as follows, I assumed that all three particles move to the right $$m \dot{x_1}=-k(x_1 - x_2)$$ $$2m \dot{x_2}=-k(x_2-x_2)-3k(x_2-x_3)$$ $$3m \dot{x_3}=-3k(x_3-x_2)$$ Then I simply...

Since space is expanding, and that expansion moves things, then those moved things must be moved by something. If moved by space itself, then space must be providing the energy. And if gravity is a function of space and time interacting, then what is the energy or mass of a volume of space...

A satellite is orbiting a planet in a circular orbit. The planet's mass doubles instantly. What happens to the orbit of the satellite? I think it would move to an elliptical orbit with major axis equal to the old radius and a minor axis equal to either 1/2 or sqrt(2)/2 times the old radius. I'm...

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In the derivation of the conservation law of the conservation of mass, the flux on one side enters and the flux on the other side leaves the control volume. I presume this is due to the assumption that the volume is infinitesimally small and hence v(x,y,z,t) will not change directions...

For part (f) Solution is I don't understand why the bit highlighted in yellow is true. Would anybody be kind enough to help.

Einstein showed (via general relativity) that spacetime is curved by mass, mass moves in relation to this curvature, and that gravitation arises as secondary effect. Why then are we looking for quantum gravity as some sort of mass<->mass interaction? Aren't the fundamental interactions better...

I was reading a recent physics article on the google home page that stated that the current theory of mass is that it is a photon moving at light speed but stationary in space. My analogy of this was like a photon moving in a circle but it is not moving. I wish I could sight the article but...

How is the mass inertia product calculated? I have two examples and each one uses something different. Example 1: Example 2: moments and product of inertia of the cylinder

my solution: a) F(upward)=Fb +Fw =(1.3+1.5)X9.8 =27.44N total Mass = 2.8kg b) Volume increased = π(0.2/2)^2 x 1.5/100 =4.7x10-4 m^3 T+Fb =mg T=mg-Fb T=2.2x9.8 -1000 x 4.7x10-4 x 9.8 T=17.4N T is the apparent weight of the rock, so the mass of the rock in the water...

In Section 3.4 of Shapiro & Teukolsky (1983), a simple derivation, due to Landau, of the maximum mass limit for white dwarfs and neutron stars is given. I will briefly describe it here and then pose my question. The basic method is to derive an expression for the total energy (excluding rest...

This is a piston I had DMLS printed from AlSi10mg - the geometry is derived from generative design using some basic inputs and a starting shape. It's really just an experiment whether a consumer grade design and print can be bolted in and work for a time. After machining, it is predicted to...

^ This is my personal drawing of the diagram, I couldn't take a picture of the actual one. The setup is a pulley wrapped with a cord and mass hangers attached to each end. My first thought when approaching this problem was to first determine the rotational inertia of the pulley, then use some...

Hello! I have the following Lagrangian: $$L = \frac{1}{2}mv^2+fv$$ where ##v = \dot{x}##, where x is my coordinate and f is a function of v only (no explicit dependence on t or x). What I get by solving the Euler-Lagrange equations is: $$\frac{d}{dt}(mv+f+\frac{\partial f}{\partial v} v) =...

I've been thinking about how rotational speeds don't fall off high distances from galactic centers, for which dark matter is generally an explanation for the increase in acceleration Speed = distance / time But time is relative What "time" is used in these calculations? Wouldn't time be...

I am looking for a formula that I can use to find out how high a steel rod or ball will jump up. If I hit mass M with force F how high will it jump up. If there is a program that would be great. every thing will be in pounds So if ball or rod of 10 lbs is hit on the bottem with 14 lbs of force...

So i got some equations but i think i am missing something, my main doubt is what is the relation between dx / dt and v(o) [ here] . Workings in attachment

What I did was plug in the outer radius time the force into the torque and then the mass moment of inertia is equal to m*ro^2 so then I plugged in the mass times the radius of gyration squared into I and solved for a but this is not right.

Is it possible to have a universe with only space and time but no mass ? I ask this question because a friend told me that time is an illusion. In fact, time does not exist. Because of the existence of matter, time can be felt through the movement of matter. If matter does not exist, time does...

Since the question made no indication of the disk rotating about its center, I just straight up assumed that the disk did not rotate about its center, and instead treated it as a point mass. However, to my surprise my calculations did not bear me any fruit. Below is my first attempt at the...

What force causes the surface to move to the left? Can I say that it's due to the force component of the weight along the vertical force of the surface?

What I have already attempted is on my Ipad and I don't know how to upload it on here. With hope of help DJ

I used the regular way of solving problems with pulleys. I tried to find the tension forces, which must be the same in the rope, but I get it wrong

I tried approaching this question like this: F_N - mgcos(theta) = -mR(theta_dot)^2 and theta_dot = v/R since R is constant F_N = m(gcos(theta) - (v - v_0)^2/R) (with v being final velocity and v_0 being the initial velocity from the impulse) and then using energy conservation: at t = 0: E =...

Net torque = 2gx20xcos30 - 2gx35xcos20 - 2gx15xcos60 + 2gx30xcos80 = -357Nm Have I done it right?

I tried using the equation w^2 = (4*K)/(mr^2) but I don't think this is right... I got my answer to be 3.2243 and that's not correct

I'm not sure where to start, I feel like I'm missing the mass but it is not listed.

I calculated the following in the attached file, I hope I did it correctly...

I have a conceptual question about this problem. I can write the 3.5 kg block equation as Fnet(block 1)=(Force of tension)-(Force of friction)=m1a I can write the 2.8 kg block as Fnet(block 2)=(Force of tension)-(Force of gravity2)=m2a My question is this If I set the forces of...

Stars are basically large objects that convert mass to energy as allowed by the mass-energy equivalence in special relativity. So I was thinking, following the same equivalence, shouldn't the reverse be possible too? I.e. a kind of reverse star that sucks in energy and converts it into mass? I...

On the test, I said they hit the ground simultaneously. However, that, in retrospect, doesn't seem to be the correct solution.

Hi , Can someone tell me wether my answer is corrrect or false ?

tried writing the x position as x = Acos(wt) (ignoring the phase) so that d2x / dt2 = -w2x Substituting that into the individual motion equations would get the required result for the individual masses, but I am not sure how to combine the equations to get the reduced mass

Unfortunately, this is not the right answer.

I got 13N but is that right because apparently, it's wrong Here's my work: F = mg = 2(10) = 20N F = ma a = F/m = 20/4+2 = 20/6 = 10/3 = 3.3m/s^2 T = mg - ma T = (2kg)(10m/s^2) - (2kg)(3.3m/s^2) = 13.4 N I appreciate it! And if I'm wrong could you show how you got your answer? Thanks

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...

So, I use Ansys (well known FEM software) and get the next output for a modal analysis toy problem (If you happen to know Ansys that's a pre, but I promise it shouldn't matter). The problem is a simple beam, clamped at one end. I used 160 20-node brick elements to solve it (so no Timoshenko...

Has anyone looked into the details of stellar orbital speeds and required (visible) mass distribution in the Milky Way? Doing some math here - if the local mass density is significantly higher in the inner 10-15% of the galaxy, and then lower and gradually thinning outwards in the disk, we will...

I am new to this forum and in line with its rules I am trying not to repeat a question already asked. I find that Jeremyfiennes original question I.e Experimental evidence for effective mass increasing with speed” is the question I want to ask but I am not satisfied with the answers given so...

This is a homework problem of my grand daughter. The question is to find out the conditions of an object M on a slope with angle shown and applied force "F". I find there are 3 conditions, sliding up, sliding down and not moving. This is my work. I just want to get comments on my work: At the...

Gravity isn't a force in the strictest sense of the word, yet magnetism is exactly that: a force. As is strong, EW, etc. Therefore, it's possible that the more massive magnetic object gets drawn to the center of a magnetic source at a faster rate than the less massive magnetic object. Discuss!

Hi I'm just a student so this: F = - mg - kv (Being kv friction) doesn't sound intuitive. Looks like both are going in the same direction... I just don't get it. But that's what my book says (Symon mechanics) and my classmates are also using "-"kv . Can someone explain me please? Shouldn't...

I understand that the uncertainty is low when you're dealing with a "macro" scale area that is much bigger than Planck's constant. But what's confusing to me is when you know with extreme precision the location, but there's so many particles involved that there is little uncertainty since the...

I have a question. If we assume that ##dm## is positive, is the answer supposed to be different from the one when we regard the ##dm## as negative? 1. If I assume that ##dm## is positive: By using momentum conservation, we will get $$mv=(m-dm)(v+dv)+dm (v-u)$$ simplify the equation $$m \,dv=dm...

Since high frequency photons have more relativistic mass, should we expect them to bend more than lower frequency lights when traveling through a gravitational field, thus produce a rainbow effect? But we don't seem to experience rainbow effects with star light.

If I start with two, otherwise isolated, masses M and m initially together and do work to separate them then the work done, I assume, goes into the gravitational binding energy between them. Will the system of mass M and m have increased in mass due to this in accordance with e=mc^2? I...