Body Definition and 1000 Threads

Homework Statement One body of constant pressure heat capacity C_P at temperature T_i it's placed in contact with a thermal reservoir at a higher temperature Tf. Pressure is kept constant until the body achieves equilibrium with the reservoir. a) Show that the variation in the entropy of the...

Ok so I'm trying to show how a bullet in real life will not actually make a person fly backwards like it does in movies. I have some idea of how to go about this but need help. So far... I know it's a perfectly inelastic collision since the bullet sticks into the person so would I have to use...

Hello.. The query is regarding thermal conduction of heat from a solid body: Suppose we have a long metallic rod which is insulated on the curved surface and one of the bases. If we supply Q amount of Heat for a small time to the rod from the non-insulated end, initially the temperature of...

Homework Statement http://i.imgur.com/0h6dF.png Homework Equations ƩFx=0 ƩFy=0 ƩMo=0 The Attempt at a Solution not sure what unknowns are

Homework Statement https://dl.dropbox.com/u/66988308/Capture.JPG Homework Equations V=rWThe Attempt at a Solution I tried to plug in the forumla , and algebras but I keep getting rc/rf as answer instead of rf/rc as the book says. Work: Vf=(rf)W W=Vf/rf W=Vc/rc Vc/rc = Vf/rf (Vc)(rf) = (Vf)...

Hi guys, I'm working on one assignment about C-Spanner screw an impeller failure analysis. However, we're unsure if the free body diagram we draw is correct or not, given that our calculated safety factor is unreasonable. Can anyone give us a hand and have a look. Moreover, if someone can...

Homework Statement A 60 kg man stands in a 30 kg box on a light weighing machine. If the box is kept at rest due to force applied by the man by the rope , what is the weight shown by the weighing machine? Homework Equations The Attempt at a Solution .answer given in book is 15...

Homework Statement How would the free-body diagram of two 45 degree right angle wedges stacked on one another look like? (It is stacked so that the two wedges form a square) There is friction that is holding the wedges together. The wedges are in place and not moving. ___ |\ | | \| ----...

Homework Statement Identify all forces acting on the object and draw the free-body diagram. Draw the force vectors with their tails at the dot. The orientation of your vectors will be graded. The exact length of your vectors will not be graded but the relative length of one to the other...

Homework Statement A force of magnitude F= 7.30 N pushes three boxes with masses m1= 1.80kg, m2= 3.00kg and m3= 4.20kg, on a level surface. Draw a free body diagram showing all the individual forces acting on the system consisting of boxes 2 and 3 together. Indicate the directions of the...

This problem is for a Fluid Dynamics course, but it is mostly math and thus I figured it should be posted here. If it should be moved elsewhere, please let me know and I will do so! Homework Statement We saw in class the hydrostatic force acting on a body at rest in an incompressible...

Homework Statement The picture attached is the problem. Also given is the constant acceleration of 2m/s^2, a frictional force of 75N, and the mass of block A is 25kg. Homework Equations The Attempt at a Solution I just need help with drawing the free diagram part involving the normal force...

In the figure below, m1 = 10.5 kg and m2 = 3.5 kg. The coefficient of static friction between m1 and the horizontal surface is 0.50, and the coefficient of kinetic friction is 0.30. I've drawn the free body diagram myself and labeled it but don't know how to structure the equations and stuff...

Homework Statement Now , I Will Begin by stating the calculation and i will post the query at the end. so here we begin, we know that If W is the work done by a conservative force, potential energy change is given by: ΔW= - ΔU ...(1) ie when work done by conservative force is positive...

Homework Statement Assume the system is massless. The Attempt at a Solution Here is my quick attempt at drawing a free body diagram for this system: What I am not sure about is the direction of the force at F. Should the force be A or B?

Homework Statement Much of the of heat lost from a cross-country skier's body is radiated from the head, since it is often uncovered. Treat a head as a 20-cm-diameter, 20-cm-tall cylinder with a flat top. If the surface temperature of a body is 35 C, what is the net rate of heat loss on a...

When a black body is heated the colors listed are IR, red, orange, yellow, white, blue-white, UV. Why doesn't a black body radiate all colors when heated: Red Orange Yellow Green Blue Indigo Violet? And why not shades of these colors?

Hi everyone! Which is the formula and the proof of the projection of the angular momentum of a rigid body along the rotation axis? I searched on the web and on my mechanics book but cannot find anything... does somebody know this curiosity ?

Hi I am making physics engine (computer) and i have some problems with interpretating multiple forces on one body. http://img837.imageshack.us/img837/396/75i7i47i6.png On the fourth car (on right) there are two forces acting on two rear wheels, interpretation is obvious, but what when...

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...

scenario - A free falling body impacts water at terminal velocity. During what time period is the body considered to be in impact. I am trying to calculate the impact force alone. Is the impact force considered at the initial contact, during the body is fully transitioning from one medium to the...

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...

Hello all! I'm a programmer looking to put together a system modeling the force a character's limbs exert on the environment as that character moves around. Characters can either grasp (with a hand) or press against (with a foot or something) viable contact points in the environment in order...

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've been having trouble with a certain part of a homework problem. I wish I had posted this earlier so there would be more time! Anyway... The shape is a semi-ellipsoid (a Rattleback, in particular). Here's a good picture of what I'm talking...