# Tagged Questions

Questions related to the Continuum Mechanics Division of Elasticity. The bending of beams, deflection of rods, or in general, applications of Hooke's Law generalized to three dimensions.

17 views

### Which weapon can transfer more energy to a projectile: sling or slingshot?

Which weapon can transfer the most energy to a projectile, a sling or slingshot? Each is totally powered by a person, one stores energy in elastic the other kinetically. Which can store and transfer ...
12 views

### Interpretation of Evanescent Elastic Waves for Material Damage

In elastodynamic theory, when the slowness vector is imaginary, the resulting elastic waves are called evanescent. I have read that this corresponds to exponential decay. I have also read that complex ...
29 views

### Is it possible a linear compression to result in rotational movement? [on hold]

I am looking for a spring or elastic mechanism that I will compress linearly; and when I let it go, it will rotate. Is there such a mechanism or spring?
140 views

### Will a tennis ball go further if i hit it with the side of the racket?

If i hit a tennis ball 'properly' on the stringing, does it go further than if i rotate the racket 90 degrees in my hand and hit the ball with the same force, but on the side of the frame? I'm ...
415 views

### Fundamental frequency of a material and its Young's modulus

I wonder if there is a connection between fundamental frequency and Young's modulus of a material. For example, how to calculate the Young's modulus of a glass bar by knowing its frequency spectrum?
37 views

### Parabola or Catenary in this case?

Exhibit A: the flexible film sinks into the box due to lower internal pressure inside the box. question is, does the film form a paraboloid or a 3D catenary or neither? this is the usual method used ...
35 views

### Rubber on atomic scale during bending

When you compare rubber with steel whats the difference on the atomic scale when you bend it?
4k views

### Why is the vibration in my wire acting so oddly?

I was soldering a very thin wire today, and when I had one end firmly soldered, I accidentally bumped the wire diagonally with my tweezers. What I'd expect to happen is that the wire oscillates for a ...
1k views

### Inflating a balloon (expansion resistance)

I am doing a quick calculation on how to calculate the pressure needed to inflate a perfectly spherical balloon to a certain volume, however I have difficulties with the fact that the balloon (rubber) ...
15 views

### How does linear elasticity deal with Heaviside forces?

For a particular elastic material with prismatic geometry, I observed a linear relationship between stress and strain but the forces applied to the material are given by a step function where the ...
14 views

### relationship between creep and hysteresis

For a particular material that's suspected to be viscoelastic, I observe a hysteresis curve where the difference in elongation between the loading and unloading curves ranges between 5% and 10% for a ...
42 views

### theoretical explanation for smaller Young's modulus of silicone foam

I measured the Young's modulus of a rectangular silicone foam sample which is equivalent in material constitution to silicone rubber except that it is 80% empty. The Young's modulus for this foam was ...
39 views

### Marsden and Hughes Mathematical Foundations of Elasticity Derivation

in the beginning of the book they discuss transformation between coordinate systems and they use this to show that the velocity of a point transforms into that coordinate system;, in terms of the ...
42 views

### necessary and sufficient conditions for linear elasticity

If it's experimentally observed that a particular elastic isotropic material has a linear relationship between stress and strain for a certain range of stresses and strains, does it follow that a ...
70 views

### Estimating Young's Modulus

In order to measure the Young's modulus of a rectangular sample of elastic material I subject it to a vertical load along its major axis using weights of gradually increasing importance and measure ...
64 views

### the poisson ratio and conservation of volume

In order to measure the Poisson ratio of a rectangular sample of elastic material I subject it to a vertical load along its major axis using weights of gradually increasing importance and measure the ...
60 views

### Impulse in perfectly elastic collision

I am implementing this simplified model at the moment, and I am trying to get my head around the physics concepts behind this model. Event-Driven Simulation So the model has two parts, first is ...
10 views

### stress concentration and geometry of elastic sample

If a rectangular sample of rubber and a cylindrical sample of rubber are both stretched along their major axes I am told that there will be less uniform stress concentration in the rectangular sample. ...
9 views

### Bending and elastic torques origin problem

In the picture, the sheet of metal is hinged and rotated with angular acceleration alpha, bending is quite small. Problem I'm facing is, where is the origin for torque due to elastic forces (M), what ...
553 views

### Determining flexural modulus by performing 3 point bending test using hollow cylindrical tube

I would like to decide the flexural modulus of the material of plastic tube by performing 3 point bending test according to the ASTM D 790 procedure. In ASTM D 790, the form of the specimen is ...
17 views

### ultimate tensile strength for elastomers

I'm doing experiments with an elastomer and I'd like to know how I should determine tensile strength in practice. Is this the point where I begin to observe tears in the elastomer or where the ...
203 views

### What equation predicts at what point a stretched object comes apart?

I am creating a simulation and am interested in pulling stretchy things and when they break, like taffy. I imagine this is a bit tougher then a simple equation like gravity, but I have no idea. Is ...
38 views

### Understanding stress-strain calculations

I'm trying to compute the stress-strain curve for an elastic material with cylindrical geometry subject to an increasing uniaxial load. I understand that this requires: stress = $F/A_0$ where $A_0$, ...
28 views

### Understanding stress-relaxation for viscoelastic materials

I'm studying a viscoelastic material with a cylindrical geometry and I read that for fixed strain(i.e. fixed elongation), I should observe decreasing strain over time. Given that stress $= F/A_0$ ...
22 views

### Modeling rubber foams

Are there any good papers/texts on the subject of modeling the dynamics of rubber foams? So far I haven't found any good papers/texts that cover this particular subject and I've done some searching. ...
109 views

### Mathematical expression of energy storage

I'm trying to develop an idea which is as follows. Put simply, imagine a flat sheet of material which, when distorted (I.e. curved in the third dimension) stores energy. Now, by calculating the ...
43 views

### Studying dynamic elasticity for finite deformations

this is not a question asking for help with a problem but one asking for help where to begin serious study of elasticity, particularly that applied to dynamic systems. Most textbooks about elasticity ...
13k views

### Why is filling a balloon from your mouth much harder initially?

Why is it that when you first fill up a balloon, it's hard to get air through, but after inflating it a bit, it becomes much easier to further inflate the balloon?
309 views

### Relationship of the volume of a plumbing system to pressure

How does the volume of water a plumbing system holds vary with water pressure? I know the ratio would include the modulus of elasticity of the plumbing material, the total surface area of the plumbing ...
51 views

### Are hardness, strength and toughness of materials not the same thing in a way?

I had to look through several videos and re-read Wikipedia statements about these material properties several times before I could even begin to differentiate them. However, now that I have found out ...
33 views

### “Poynting vector” for transverse waves in elastic solid

What is the expression or name for the vector that gives the direction and intensity associated with the energy flux or momentum flux carried by transverse waves in an elastic solid?
33 views

46 views

### Why does a bungee jumper continue to move downwards beyond the equilibrium position of the jumper and cord?

When a bungee jumper jumps, ignoring the mass of the bungee cord, the jumper initially falls in freefall before an inelastic collision occurs between the jumper and cord, and the cord extends as the ...
23 views

### Hooke's Law in 3D and in plane stress problems

Using Lame's constants, the Hooke's law of isotropic materials in 3-dimensions can be written as:  \begin{aligned} \sigma_{ij}&=\lambda \varepsilon_{kk}\delta_{ij}+2\mu\varepsilon_{ij}=c_{ijk\...
37 views

### Illustrating the definition of Young's modulus from spring factor

The relationship between Young's modulus $E$ and the spring factor $k$ from Hooke's law is $k=\frac{E A}{L_0}$ where $L_0$ is the initial length of the stretched material and $A$ the cross-...
155 views

### Derivation of elastic energy per unit volume

So I basically asked this question a little while back and didn't get much help, but I really need help, so I'm coming back and asking again. Looking at the section on Continuum Systems on the ...
47 views

### Speed of Sound in matter

So basically when it comes to the speed of sound, it is said that speed of sound in media is based on two main factors - 1)elasticity and 2)density from the formula V= $\sqrt{E/\rho }$ where E is ...
597 views

### Range of poissons ratio

I know the range of poisson's ratio is -1 to 0.5 but how do you arrive at this expression? I am a 11th grade student and I am not too familiar with advanced physics
300 views

### A moving brush on a vibrating surface

Hi group, I am a HS student in China preparing for a regional Young Physicist Tournament even. We are very puzzled about why would there be such movement. We would be grateful to see any inspiring ...
92 views

### Why does a ball eventually stop?

I was wondering, if the force of friction with the ground does not make any work on the ball and just give it the necessary torque to rotate (hence the consideration of static friction coefficient in ...
131 views

### Difference between stiffness and damping?

I understand stiffness as the extent to which an object (e.g. a mass spring) resists deformation from an applied force, or the rigidity of an object. And I understand damping as the energy ...
18 views

### Derivation of expression for sagging of a beam [duplicate]

I read in my physics textbook that: A bar of length $l$, breadth $b$ and depth $d$ when loaded at the centre by a load $W$ sags by an amount given by the expression $Wl^3/(4bd^3Y)$ where $Y$ ...
Consider a stretched elastic string. Then conducting a thermodynamic analysis of the elastic string. The approach is very similar to that used for $(P, V, T)$ systems, with the pressure and volume ...