Body Definition and 1000 Threads

A thin wire of length L and uniformly density ρ is bent into a circular loop with center at O.The moment of inertia of it about a tangential axis lying in the plane of loop is. Ans : Mass M is not given,but ρ is given. So M=ρL3->(1) (L3 means L cube,no idea how to post it in that manner!). For...

Hello I need some help with formulating the constraint force for a sliding and rotating box. The scenario is: A box is sliding down a slanted table. The center of gravity has passed the edge of the table so the box receives a counter force and torque. I am solving the forces and moments...

Make a rough estimate of the volume of your body (in cm3). 8X10^5 cm^3 8X10^3 cm^3 5X10^4 cm^3 5X10^3 cm^3 8X10^4 cm^3 How to solve this problem?

Homework Statement A ball is dropped from the top of a cliff. If time taken for half of the descent is 3s, then what is the time taken for the rest of rest of the descent? Take g=10m/s2 Homework Equations T=√(2h/g) v=u-gt s=ut-gt2/2 The Attempt at a Solution T=√(2h/g) h=T2g/2=45m...

My question is suppose we go to sleep without setting an alarm and intending to get up only when we wake up. How does the body know that it needs X hours of sleep at night. Is our subconsciousness monitoring our stress levels and when it has determined that our stress level is sufficiently low...

Homework Statement This is problem 7.7 from [kleppners mechanics...

We know that a lot of bacteria are present in our body like in our stomach etc. Where do they come from? It's hard to think that at fertilization there is information stored somewhere in the fertilized egg that these bacteria are to be produced which will help in digestion. In other words they...

Dear All, I have come across with a seemingly very simple problem but could not solve it by searching on internet and books. May be I am confused. I want to rotate a 3D body around an arbitrary axis with fixed principal axes. The solutions I found is with Euler angles (Euler rotational...

Hi everyone, I have a very simple and classic question here. Suppose I have a 10cm,0.01kg ruler (uniform density) in space. And I apply a 1N force 2 cm from the left end of it. What happened at this instance? I guess centre of the ruler will start to accelerate as a=F/m=100ms^2. But what...

I'm looking at the free energy of a body (theory of elasticity) but I can't really square the general expression with the one usually used for isotropic bodies. According to wikipedia (http://en.wikipedia.org/wiki/Elastic_energy), Landau & Lifgarbagez etc the general expression for the free...

Homework Statement A thin uniform rod is attached to an axis through its midpoint. The axis is standing on a disk rotating with constant angular speed \Omega about its symmetry axis. The rod's midpoint is located directly above the rotational axis of the disk. Let \theta denote the rod's...

Just a quick question relating to thermal equilibrium between a hot and cold body. If a hot body and cold (closed systems) are opened up to each other, the thermal energy will be transfer from the hot body to cold body through conduction. So even when thermal equilibrium is reached, the...

I read his book "Demon Haunted World" many years ago. I recall that he referred to an experiment where a computer controlled digital readout was placed in a high location not visible to people in an emergency room of some hospital. This display showed computer controlled random words to test...

Homework Statement If a 4kg block is placed on top of a 5kg block which placed on a friction less plane and a force is applied on the lower 5kg block ,For what maximum value of force will the top block not slide ? μ=0.036 Homework Equations The Attempt at a Solution The maximum static...

Hi, I have a question about basic statics. I have heard from someone that the forces acting on a truncated cone in a hole of corresponding geometry is different from an ordinary block sliding down a wedge, since the normal force on one side of the cone will be affected by the normal force on...

Hi everyone, I would like to know if the energy of each body of a two body gravitationnal problem is separately conserved. I know that the individual angular momentum are separately conserved and that the TOTAL energy of the two bodies is conserved. However, I don't know if there could be...

I have arrived at the contradictory conclusion that a body can have a positive or negative velocity and not be moving(variating it's space). It is contradictory because if it has a positive or negative velocity it must be moving (variating it's space) since velocity is a variation in space, as...

Hello All, Greetings. I am new to this forum. I am working for a heater project, in which we use plastic (PA66) over molded on aluminum (6061-T6) body for melting corrosive liquids (similar to sea water). The Aluminum body is heated by means of Positive temperature coefficient material (PTC)...

Hello, I'm trying to determine whether my work for the following rigid body motion is correct, and if so why I'm not able to verify equivalent formulations. For the sake of simplicity small angle approximations will be used, and cross terms were neglected. Homework Statement...

Let me cut to the chase. What are the chances a undergrad who took junior level mechanic class can make useful original research on the 3 body problem? If my understanding is right it hasn't been solved yet. I've been studying from Landua and studying from Taylor and just finished learning about...

Will the friction act on a body at rest. Do not take in the case of inclined plane.

Homework Statement As shown in the attachment, a free body diagram (FBD) must be drawn Homework Equations sum of horizontal force = 0 sum of vertical force = 0 The Attempt at a Solution 1. Forces F1 and F2 appear exactly as they are in the FBD 2. At point A, there is an outward horizontal...

Why does head and body hair differ? Doesn't monkeys have the same type of hair on their head and the rest of their body?

I'm trying to write AI code for a program, in which a spaceship has to rotate to face a target. I've somewhat idealised the situation - the ship can yaw, pitch and roll with a maximum angular acceleration along each axis. I'm representing the rotation of the ship relative to the world...

I have to deal with the problem of finding an expression for the kinetic energy of a rigid body. One of its point is pivoted to a point that moves arbitrarily. So in order to find an expression for the kinetic energy I use König's theorem, but I need the velocity of the center of mass. I use...

Apologies if this is the wrong topic, but I think it's relevant under GR since it involves curved space time and I can't see it applying to Newtonian systems. I found an article about swimming in space by deforming one's body. This should not be possible according to my understanding of...

Hey all, Say you have a slab sitting vertically(like a door) at rest on a frictionless surface. If you push with a horizontal force somewhere near the top(as long as it is above the center of mass), would the slab rotate(tip over)? My friend and I were originally thinking of how much...

After doing some work with a painter friend we were coming home and I put my arm outside of the window as we were going 70 miles an hour. Wondering what the g-forces would be on my arms and hand? Thank you

Hello. I'm currently coding on a physics engine. To do so, I looked up some code from open-source engines. I noted that there is a function where you can apply a force to a rigid body, outside it's center of mass. It goes something like this: ApplyForceAPosition(vector force, vector...

Hello, I have a rectangular object with the following properties: Mass (m) = 1 units Moment Of Inertia (I) = 4.41 units initial velocity (v_{i}) = (5, 0) initial angular velocity (w_{i}) = 0 If the block collides with a solid rigid wall with distance vector r = (1.1, 1.4) from the...

Would an ideal black body be visible to us? What about Ferry's black body? How close was it to an ideal black body?

Hi everyone! Anyone knows what is the maximum displacement covered by a body in a time equal to half of its time period? Please also give an example. Thank you.

Homework Statement Hello, I'm having some issues deriving the momentum equation for rigid body motion in a non-inertial frame. Consider a rigid body moving in a two dimensional (inertial XY) plane. A body fixed frame (origin denoted as B) is located off the center of gravity. The body has...

Having an infuriating time trying to explain physics to co works. The debate is as follows: to get to Pluto in a quick time, say less than a year, you would have to travel extremely fast. If it were possible to reach such a speed via rockets/ion drive the human body would be crushed under the...

Hi, my question in full; Do DIFFERENT observers (in different INERTIAL reference frames) see a DIFFERENT force (Magnitude specifically) acting on an accelerating body? I believe yes . Because... : ƩF = d(p)/d(t) = m*a + v * d(m)/d(t) where m = m0/√(1-v^2/c^2) where v is different...

Hi all http://store2.up-00.com/June12/pG127901.jpg V^2 = u^2 + 2as V = 8.85 m/s which will be intial veloctiy befor hits the second body Bu using e(u1 - u2 )=V2 -V1 m1u1 +m2u2 =m1v1+m2v2 for the body which is 20 N mass 20.3 u1 = 8.86 0m/s V1 after collision = 0 m/s...

Can a body which has no initial velocity move just with acceleration?

Hi all! I need help..:) I need to model the dynamic of this system: I'm in the plane (2-dimensions). There are two points (with m1 and m2 masses) free to move with different speed vectors (in module and direction). At some point, when the distance between them is d, the two points...

I'm still a student who is studying physics and I want to become a theoritical biophysicist, but I don't know what I need for this department.

Homework Statement When I push my belly forward, a force is exerted on my belly by my muscles. So there will be a reaction force acting on the muscles right? But eventually it has a net forward force. So if we treat the belly as one object (muscle fat everything in the belly) then where is the...

So this is a conceptual question, it's not a direct homework question, but it does involve how to do a kind of calculation. I hope this isn't the wrong place to post a nonspecific question like this. In the case of a board/stick/ladder leaning against a wall, about an axis O at the bottom of the...

Homework Statement Draw three free-body diagrams showing the forces acting on a toy suspended by a vertical spring. The diagrams should show the situations when the toy is at its equilibrium position, and above and below the equilibrium position. Homework Equations The Attempt at a...

Hi all 1 ) Direct central impact occurs between a 300N body moving to the right with velocity of 6 m/s and 150 N body moving to the left with velocity of 10 m/s . Find the velocity of each body after impact if the coefficient of restitution is 0.8 . my answer : Given [/color]...

So as I understand a perfect black body in physics would be one that would absorbs all the radiation wavelengts coming onto it ad let nothing out? If sun is a black body, we all know it emits both visible wavelenght, UV and other.The vast majority of the spectrum being in the visible light...

A body moving with simple harmonic motion has an amplitude of 1 meter and the time for one complete oscillation is 2 seconds . Determine the velocity and acceleration of the body after 0.4 second from the mean position ? this is the answer : Vx = w root(r^2-x^2) ax=w^2.X w= 2Pi/t =...

hi let me says you have an arbitrary rigid body and a force F acts on this body at some point A, which is not the center of mass that is called C. how do you get the equation of motion? my idea was to separate out translation and rotation: maybe the whole body moves by F=ma and...

under what conditions can a rigid body collision problem be solved using a system approach, (i.e by using the conservation of angular momentum of the two rigid bodies about some point) the equation M=d[H]/dt is only valid when M and H are taken about a point fixed in a massless extension of a...

Homework Statement See attachments Homework Equations The Attempt at a Solution In the explanation attachment, I don't get the last paragraph "Note that force Fce acts downward on bar...compression." Since from the figure Fce is pointing down, and Fbd is pointing up, shouldn't...

A perfectly rough rod is gently placed with one end upon another rod of equal mass and in the same vertical plane, moving with the velocity √2gc on a smooth table. If the initial inclination of the first rod to the horizon be α, and its length 2a, shew that it will just rise to a vertical...

1 ) If a body is rotating at uniform angular velocity then in t sec , the angular displacement is ... (complete ) my answer the angular displacement is increase . 2 ) If a body is making N revolutions in one second then its angular velocity in rad/sec is my answer the angular...