Body Definition and 1000 Threads

Hi everyone, I was recently talking to someone with a non-maths background about rotational stability, in particular how rotation is stable around the largest and smallest principal moments but not the intermediate one. He asked me if there was any 'obvious' reason for this, but one didn't...

My name is Bradley and I am a first year university student attending Intro to Quantum mechanics lectures but didn't understand... Why the black body radiation curve (unlike the quantized emission seen from atomic spectra), is continuous over all frequencies. I am wondering what exactly gives...

1. The problem statement, all variables and given/know Say I have a can of water, and I am rotating it about its central axis at a constant angular rate. The water in the tank should make a 3D almost parabolic curve as it touches the the walls of the tank. Can I use Bernoulli's equation along...

Homework Statement Suppose I've got a static mass on a downward plane. (For instance a car on a drive way). How would you set up this free body diagram? Homework Equations F = f1+f2...etc The Attempt at a Solution My preference is A, but I've seen it displayed in examples in my book as B...

Homework Statement In figure (a), four identical crates weighing 2,000 lb each are stacked one on top of another, and in figure (b) a simple model for determining the deformation of the stack of crates is shown. In this model, each spring has the same stiffness k = 4,500 lb/in. and the forces...

Homework Statement A collar with a pulley slides on a frictionless vertical bar GH. A string A B C D is wrapped around, where portion AB of the string is horizontal. A spring with 2.5 lb/in. stiffness is placed between the collar and point H. The spring has 7 in. unstreched length and 5 in...

Hey all, question about gravitational potential energy. If an object begins on ground then gains height when it falls then energy it consumes to fall down was the potential created by moving upwards, if an object was created in space, then moves gravitationally towards a celestial body where...

Hi, I have a question about rigid body rotation. If I have a rod out in space in free float and I attach a battery powered fan to center of mass and then the fan is turned on to spin in a clockwise direction, then the rod should spin in a counterclockwise direction. This much I...

It's the best science fiction novel from my country for now. First long Chinese sci-fi novel translated into English. Written by an "electrician" as we call him, but Liu Cixin(刘慈欣) was actually an software engineer, that worked at a power plant.

I was just reading about Archimedes principle. Suppose a cylindrical body (attached figure) is immersed in liquid of density d. if the weight of body outside liquid is Fout then can we say that this body will immerse in liquid when released to a depth where upward force F2 = Fout. And then it...

Hey guys, what do you think about this: Let's put a planet in empty space, on the surface of the planet we put a a guy named Bob, Bob's task is to accelerate the planet by pulling on a provided rope. He must extend his arm, grab the rope and bend his arm at maximum force. Bob's identical twin...

Homework Statement You throw a ball vertically upward from the roof of a tall building. The ball leaves your hand at a point even with the roof railing with an upward speed of 15.0 m/s; the ball is then in free fall. On its way back down, it just misses the railing. Find (a) the position and...

Homework Statement A ball is thrown vertically upward with an initial speed of 19.6 m/s from the top of a building 44.1 m tall. Assuming that there is no air resistance. a.) At what two times is the ball 10.0 m above its starting point? b.) What is the position of the ball at t = 5.00 s? c.)...

Homework Statement Two blocks sitting on a frictionless horizontal surface are connected by a light spring. The natural length of the spring is ##d##, and the spring constant is ##k##. The two objects are initially both at rest, with the spring neither stretched nor compressed. At time ##t =...

Homework Statement Consider two objects with masses ##m_1## and ##m_2## exerting forces on each other with magnitude ##F##. If no other net forces act on the objects, they obey the equations of motion ##m_1\ddot r_1=F##, ##m_2\ddot r_2=-F## Show that the corresponding equations of...

Hello everyone! I'm a aerospace engineering student. I'm working in my own program for blended wing body aircraft parameterized design. I'm triyed to use Tornado program but it doesn't even allow me to setup the geometry, after introducing the chord the program goes in a bucle and when I stop...

Hi, I am trying to implement a low tech, quick "check" source for our radiation thermometers to ensure they are in good working order between calibrations again a calibrated black body radiation source. My idea was to use an integrating sphere with an incandescent lamp as a source. Then two...

Hello, I am looking for the general direction that I need to go to calculate the following: The time-dependent change of temperature of a finite, but continuous, mass of air moving across a water/air boundary. Let's say you have 150 degree F air moving at 0.007m^3/s over a relatively infinite...

Hi everyone, i was reading the article of Cristenson,Cronin,Fitch and Turlay of 1964, the one that discovered CP violation in the system of neutral K mesons. There is one point in it that i don't get it. They say "the angle should be zero for two body decay and is, in general, different from...

This stems from considering rigid body transformations, but is a general question about total derivatives. Something is probably missing in my understanding here. I had posted this to math.stackexchange, but did not receive any answers and someone suggested this forum might be more suitable. A...

Homework Statement A body is moving on an inclined plane which has a slope of 30o. When the body is h=1,5m above the surface it has a velocity of vo=3 m/s. At the bottom of the plane it bounces elastically and starts moving upwards. Find the height it reaches, when the coefficient of frictions...

The astronauts who were traveling to the space. in what way their health were affected? During the rocket launch the spacecraft should travel greater than the Earth's escape speed. Is this speed affect the astronaut? And tell me which is the maximum speed that our human body can bear?

Hi, I once considered myself enough to be decent enough to solve some problems but lately I'm thinking to revisit and start solving problems again. I would like to know whether there is a book good which has problems (starting from basic to tough ones) for practicing free body diagrams. The book...

Hello! While studying from the book 'Fluid Mechanics' by Cengel I came across the section which explains the behavior of fluids acting like a rigid body when the cylindrical container which contains the liquid rotates with a uniform angular velocity. Without much explanation the author states...

Homework Statement [/B]Homework Equations [/B] (1) (pink) Is it vertical displacement ? * 4 - 2 (unstretched length of the spring) ? (2) (blue) What does it mean ? * I was thinking that maybe they used The Pythagorean theorem (62+42)=7,2 ≅ 7) but I'm not sure. Besides I don't understand...

I know how to solve "typical" Kepler problem but I'm interested in a global view to "binary" systems. For example Earth - Moon. If I set lagrangian of system as ##L=\frac{1}{2}(m_1\dot{r}_1^2 + m_2\dot{r}_2^2)-V(|r_2-r_1|)## there isn't included a spin. My questions are: 1) If it is solved as...

If I placed a anti-symmetric object in water, and if it floats,is it possible for it to move left or right due to a force imbalance in calculating \int p * \vec{dA} . I know that if the object is a closed surface, we can apply the divergence theorem and because we also know how pressure...

Homework Statement When a force of 2 lb is applied to the handles of the brad squeezer, it pulls in the smooth rod AB. Determine the force P exerted on each of the smooth brads at C and D Homework Equations ##\sum F_x=0## ##\sum M=0## ##\sum F_y=0## The Attempt at a Solution I drew a free...

Homework Statement A body is thrown upward and remains in air for 10 seconds , the initial velocity at which it was thrown in is? The Attempt at a Solution g = -10 , t = 10 s , vf = 0 , vi = ? Vf = vi + gt 0=vi + (-10) (10) Vi = 100 but its answer is not 100 its answer is 50 help me please...

Why does a body kept on a rotating disc tend to slip away from the centre?

it is said that the energy spectrum of two body and three body decay is discrete and continuous respectively.

Hi, Could anyone help me out on how to apply pressure on a portion of a face in ANSYS 15.0, as in like a concentric area within a solid body. Thanks in advance

Starting from a locked thread I tried to work the gravity of a body of mass ##M## on another body starting from infinity to some distance ##d## from the gravitating body. We have from the SR 2nd Newton law that: \gamma^3 a = \frac{GM}{r^2} writting a= \frac{dv}{dt}= v \frac{dv}{dr} =...

I am making home automation model and I have few sensors installed to sense some changes in the environment to detect any changes. So these sensors provide me data , but I want to know what changes does Human body exerts on the environment it enters, so that I can install those sensors which...

Hi, I'm having a discussion with someone on the plausibility of the physics in a science fiction movie (I know, very efficient use of time!). There's a scene with a space station shaped like a ring. It has a center body that is attached radially to one edge of the ring. This space station is...

Hello all. After reading both chapters on rigid body motion both in Kleppner - Kolenkow and Taylor books, I still do not undertand the physical meaning of Euler equations. Let me explain: In Kleppner - Kolenkow, they claim (page 321 - 322) that in Euler equations, Γ1, Γ2 and Γ3 are the...

Homework Statement Two ropes are connected to a steel cable that supports a hanging weight as shown in the figure. Draw a free-body diagram showing all of the forces acting at the knot that connects the two ropes to the steel cable. Draw the force vectors with their tails at the knot. The...

< Mentor Note -- thread moved to HH from the technical physics forums, so no HH Template is shown >[/color] I have a problem here. what's the formula for the acceleration of a system wherein. A disk with a cylinder on top of it with a shaft underneath to wound the thread to connect it with a...

I'm trying to understand lipid pneumonia. It's been reported that vaping on electronic cigarettes, which contains vegetable glycerine, is the cause of lipid pneumonia. That claim is denied for the reason that vegetable glycerine is not a lipid. It's an alcohol. But glycerol / vegetable...

Neglecting drag, I'm trying to understand how a wheel driven by a motor on a level surface rolls without sliding and experiences constant velocity. I'm trying to construct a free-body diagram. The wheel has a weight and a normal force acting on it in the vertical directions. The sum of...

It is said that around 90% of the cells in a human body are symbiotic bacteria living thanks to us. When we die, do most of them also die? Or do they manage to survive without us and find a new 'home human'? And opposite, when and how do we get all those bacteria after conception? Do we get...

Generally pressure in a liquid changes with height at which we measure. But still blood pressure remains almost same throughout the body. How is this possible?

We know that Force= Mass x Acceleration. When the force applied on a body is 0 the accelaration produced in the body is also 0. (F=m a). So, what will be the mass of a body on which no force is applied and no acceleration is produced? [ mentor note: post moved from New Member...

I want to get a half convex lens (thick in the middle, flat on one side). And coat it in thermally and optically reactive transition filters. They are to be segmented so to reduce spread of filtering. This will give a view of the sky with any bright light inhibited at the focus. Next to the...

I want to know, excluding the sun with an appropriate boundary, whether it is possible for the balance of bbr to be positive for outerspace rather than on earth? I am thinking of a half convex with an active polariser across-the outer surface which allows through most radiation below the...

3-D Why in bcc central atoms does not touch other atoms in that layers while in that of hcp and all others cases central atoms touch atoms in that layer..

I know from physics 101 that f = ma. And if I want to lift an object straight up i have to multiply its mass times gravity (acceleration) and I get the force I need to require to overcome it. But what about lifting your body out of bed? Just the part where you physically get up from the lying...

Homework Statement In the picture, I am confused with the sign of the moments. When taking moments about D, the moment due to the 100N is taken as positive, but when they take moments about B, its negative. Homework EquationsThe Attempt at a Solution Shouldn't both cases be negative since in...

Homework Statement A black body absorbs all incident electromagnetic radiation, including visible light which has wavelengths from 380nm to 750nm. IR radiation has wavelengths that are so long they are measured in microns. That suggests that visible light has a higher frequency than IR, and...

Hi. I'm trying to write some anatomical systems for a game I'm coding, and i need some good data to work from. Our game is about dogs, not humans, but i figure a human will be close enough What I'd really like is a case study of a specific organism, and i'd like to know the compositions, by...