# What is Shape: Definition and 634 Discussions

A shape or figure is the form of an object or its external boundary, outline, or external surface, as opposed to other properties such as color, texture, or material type.
A plane shape, two-dimensional shape, or 2D shape (plane figure, two-dimensional figure, or 2D figure) is constrained to lie on a plane, in contrast to solid figures.

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1. ### B Do we 100% know what the geometry of the Universe is?

If big bang existed, than universe must be sphere, because explosion expand in all direction.. I read that universe is maybe flat so how this is possible? Why can we with telescope determine shape of universe?
2. ### B Help with personal thoughts and observations in attempt to understand the fourth dimension better

Based on info found in this forum, I have compiled info along with personal thoughts and observations in attempt to understand the fourth dimension better any input or corrections would be helpful, along with links to sites you have found helpful in your experience. Thanks! My notes...
3. ### I Do objects of different mass but same size/shape accelerate the same?

Hi. I remember having learnt in school that if you'd like to verify that bodies of different mass accelerate the same in free fall, but don't have a vacuum available, the bodies should be of same size and shape (e.g. spheres). This made sense to me back then because drag should be the same...
4. ### B When is a polygon not a polygon?

For a shape to qualify as a polygon does it have to be closed. I was just introduced to frequency polygons and was surprised to see each one was a shape that wasn't closed. The definitions of polygon that I've come across go something like, a closed shape consisting of three or more lines.
5. ### B Shape of Lenses -- Why are they always circular?

In a magnifying glass, the lenses are always circular. I don't understand why because no matter what shape the lense is, it doesn't deny its physical properties and refraction would still occur, so why are they so consistent on making circular lenses. I predicted that circular lenses may be...
6. ### I Write probability in terms of shape parameters of beta distribution

Assume that players A and B play a match where the probability that A will win each point is p, for B its 1-p and a player wins when he reach 11 points by a margin of >= 2The outcome of the match is specified by $$P(y|p, A_{wins})$$ If we know that A wins, his score is specified by B's score; he...
7. ### B Aperiodic Tiling with a single tile shape

A tile shape has been identified that can tile a surface aperiodically. Phys Org article
8. ### I Load on leaf blower as function of outlet shape

Would a leaf blower see a different load (in terms of back pressure and flow) depending on whether the outlet tube ends in, say a 1" nozzle, versus a flared out horn of 6" diameter? I am not thinking of viscosity effects here, but rather of Bernoulli type considerations. In the case of the...
9. ### B Shape & Dimensions of Containers: Impact on the Maxwell Boltzmann Distribution

1.Does the Maxwell Boltzmann distribution change depending on the shape of the container? Pressure and the volume is constant. How is the Distribution affected whether the gas is in: a,sphere b,cube c,cuboid? Why does/doesn’t the distribution change depending on the shape of the container...
10. J

### Ideal car rear roofline angle and shape for low drag?

What is ideal rear roofline(rear window and trunk) angle and shape(straight line, curve ..etc) for lower drag? Keep in mind if you increase angle, you reduce butt area / wake, but induce low pressure at rear window/trunk , if you decrease angle you increase butt/wake but increase pressure at...
11. ### I Set up equations for shape

I have a shape based on the idea of having a string, a closed loop, that is sitting outside a rectangle. The string is d longer than the circumference of the rectangle. I noted the sides as a and b. The shapes is formed by drawing a line around the rectangle with the string as a constraint of...
12. ### How can I determine the shape of an oldie acid molecule?

I have done all of the questions apart from c and d. For a I got the answer 2.58*10^_5 cm^3 B) 3.72*10^-7 cm But for c I don’t really know how to start. I first thought of using the formula for volume of cuboid but don’t know how that’d give the answer for the dimension. For D, I turned the...
13. ### I Simple model of thermal shape fluctuations of liquid interface

Consider a container filled with two essentially incompressible liquids with densities ##\rho > \rho'## and (respective) volumes ##V##, ##V'##, rotated by a centrifuge in some orbit-based space lab to maintain a roughly constant (co-moving) simulated "gravitational field" g. Let's suppose that...
14. ### I Shape Dynamics: How Can It Offer Same Predictions as GR & SR?

Developers of Shape Dynamics (as Julian Barbour and Tim Koslowski) claim that Shape Dynamics will offer in most cases the same predictions as GR, and implicitly as SR. How can this possibly be true, since they get rid of time altogether and thus of any notion of simultaneity? How would they get...
15. ### I Shape Dynamics falsifiability

Shape Dynamics implements nicely Mach's principles. But how well does it fare when it comes to Quantum Mechanics? How can it be experimentally distinguished from other theories?
16. ### What's the best shape function/element in finite element methods for phase field simulation?

What's the best shape function/element in finite element methods for phase field simulation?
17. ### What has a shape but no volume?

I was reading a Chemistry book when I read about the three states of matter. Everyone knows what they are, but I didn't know the simplest way to describe each of the three until I read this book. It said that a solid has a shape and a volume, a liquid has no shape but has a volume, and a gas has...
18. ### Find order of rotational symmetry for the given shape

Ok for (1) I would say that the order of rotational symmetry is ##8##. Would that be correct? What about ##4##? For (2) The number of lines of symmetry is ##4##. And if one would say infinity for both (1) and (2) would that be correct?And if you consider a kite. Would the order of...
19. ### B Exploring the Concept of Energy Shape: Is Energy Limited by Matter?

Physical objects have well defined shapes, but does energy ever create well defined shapes or can it only take shape within matter?
20. ### I Broadly spiralling shape from partial sums of Zeta (0.5 + i t)

The first plot shows a large number of terms of Zeta(0.5 + i t) plotted end to end for t = 778948.517. The other plots are two zoomed-in regions, including one ending in a Cornu spiral. Despite all sorts of vicissitudes, the plot generally spirals outwards in a "purposeful" sort of way. It is...
21. ### I Shape of de Sitter Universe: Is Hyperboloid Misleading?

I am confused about the shape of the de Sitter universe. The Misner-Thorne-Wheeler says it can be regarded as the submanifold given by ##-x_1^2 + x_2^2 + x_3^2 +x_4^2 + x_5^2 = k## of a flat space with lineelement ##\mbox{d}s^2 = -\mbox{d}x_1^2 + \mbox{d}x_2^2 + \mbox{d}x_3^2 +\mbox{d}x_4^2 +...
22. ### I Work Done in Changing Shape of Current Carrying Loop

How would you go about calculating the work done in morphing a square current-carrying loop into a circular current-carrying loop, without change in length while maintaining the same angular orientation with an external magnetic field. My book suggests defining P(potential energy) = M.B (dot...
23. ### I Creating a function with specific shape, intercepts, integral....

I'm trying to see if I can calculate the peak draw weight of my bow based on the draw length and the velocity of the arrow and a known shape of a curve, but I'm not quite sure how to make such a function, if there even is such a way. This is the shape of the draw weight plotted against...
24. ### I Why Does Molecular Potential Energy Curve Have That Specific Shape?

Molecular potential energy of hydrogen in dependence with atomic distance for bonding orbital is given by picture below. We can see that at large distances force between atoms is attractive and potential energy drops to minimum which corresponds to bond energy and length. This part of the...
25. ### What is the best shape for a soccer goal post?

disclaimer: this is a made up question, so I don't know if there's a valid solution possible here First let's talk about the square post, it is clear that the shot will go in only if the ball hits the side AB of the square shown below, so the probability of a shot going in is simply ##\frac 1...
26. ### I What is the size and shape of single optical photon?

Optical photon is produced e.g. during deexcitation of atom, carrying energy, momentum and angular momentum difference. So how is this energy distributed in space - what is the shape and size of single photon? Looking for literature, I have found started by Geoffrey Hunter, here is one of...
27. ### Inferring Shape of Phasors in Multi-Slit Diffraction

I know that phasors of a single-slit diffraction form a closed polygon or circle, but how could we infer the shape when phasors generated by slits of a multiple-slit barrier?
28. ### Tetrahedron Simplex Shape Functions in FEA

Hi, 2 part question trying to get tetrahedron Finite Element shape functions working: 1) How do I properly setup the shape coefficient matrix and 2) How do I build the coefficient quantities in the shape functions properly? ANY tips or corrections may unblock me and would be of much value...
29. ### Shape of graph of torque vs angular displacement of galvanometer

I know the torque will be zero when the deflection is zero and will be maximum when the angular displacement is θ0 but how to determine the exact shape of the graph? Thanks
30. ### I Which forces maintain the shape of the Milky Way?

Gravity, inertia, conservation of momentum and angular momentum are some of the forces and conserved quantities that I could think of which will tend to maintain the shape of the Milky Way. How is the separation of the spiral arms maintained?
31. ### Help with best aerodynamic shape of undertray for maximum downforce?

What is best theoretical shape of undertray for maximum downforce , maybe wing shape or venturi shape? classic "venturi shape" with diffuser "wing shape"
32. ### Velocity of wind based on the shape of a smoke trail

Hi everyone. My high-school student got the following homework exercise at school which I have problem with: Smoke from the steam locomotive is carried by horizontally blowing wind. Shape of the smoke trail is shown in the attached figure. Using the drawing, determine velocity of the wind...
33. ### I Shape of exclusion plots of WIMP

Hello! What is the reason why the exclusion plots of WIMP experiments have that "U" like shape? And what sets the minimum of the curve? Thank you!
34. ### B Shape of Hubble sphere at relativistic velocity

Consider the Hubble horizon as the proper distance over which Hubble expansion equals c, so that you are in the center of a Hubble sphere with a radius of about 13.5 billion light-years. As you approach light speed in any direction, does the Hubble horizon draw closer in that direction due to...
35. ### I Big Crunch and the Universe's shape

In another words, to discard the Big Crunch, we discard the spherical universe hypothesis too? k>0 able us to find a solution for a dot = 0
36. ### Misc. Bending a spring steel rod to shape and heat treat, DIY?

There used to be sold a style bicycle handlebar bags that used what I think is a formed spring steel rod that fit over the handlebars and looped under the handlebar stem that supported a handlebar bag. For whatever reason this style does not appear to be available any more. I think it is a...
37. ### Mass moment of inertia of a composite shape

My thought process was to get the mass moment of inertia of the rectangle and then subtract the mass moment of inertia of the quartercircle from it. The MMoI of the rectangle is: (1/3)(0.005*7850*.6*.3)(.3^2)= 0.212 meters The MMoI of the quartercircle is: (1/4)(0.005*7850*¼π 0.3^2)(.3^2) + ? My...
38. ### Altering the shape of a flasks walls

" For the conical vessel, we note that pressure is a local force, and so must be independent of conditions far away. Hence altering the shape of the flasks walls while keeping local conditions constant will not change the pressure locally, and so F = (ρgh+Pa)πr2 also holds for this flask " Can...
39. ### Is it possible to polarize a complex 3d shape?

I have this idea for LED eyes. Basically its an LED screen behind a half spherical shape. I want the user only to see what's on the display if they are looking directly at it. So for that I would need to polarize the half sphere. The half sphere can be made out of anything, the problem is how do...
40. ### I Shape of atomic orbitals

Oritals, other than s-orbitals, don't have spherical symmetry while the atomic Hamiltonian does have spherical symmetry. How is this possible?
41. ### The most efficient nozzle shape

We all know that a convergent nozzle can increase the velocity of a fluid at the throat/exit than the inlet. But there are different type of nozzles available in market now like parabolic nozzles, straight nozzles and elongated nozzles. I want to know which shape/geometry is the best to get the...
42. ### B Exploring the Relationship Between Nucleon Shape and Quark Number

If a nucleon is let say made of 3 quarks then they rather build a triangle than a tetrahedron, so they are flat ? Why is there not 4 quarks ?
43. ### I Possible illogicalness of a 3-sphere shape of the Universe's space?

Metaphorical depictions of the universe in the shape of a 2-sphere are very common. Now, let's consider mapping the three dimensions of space onto the "surface" of a 3-sphere. Like Non-Euclidean de Sitter geometry. The surface of a sphere is positionally symmetrical. However, the positional...
44. ### Please check my calculation of the resistance of this wire shape

I explained what I want to tell you in the picture I add. Thanks in advance.
45. ### Is Lifting Lower Weights Necessary to Keep Shape?

If a person lifts weights at a particular level (by level I mean the weight amount for each exercise) and wants to keep his or her current "shape," then is there any reason that person ought to left lower levels? For example, let's say you curl 10 lbs. of dumbbells and like the figure you've...
46. ### Policy for pandemic issues and how models shape it

https://www.sciencemag.org/news/2020/03/mathematics-life-and-death-how-disease-models-shape-national-shutdowns-and-other This shows how policy can be informed about differing effects of control policies in different environments. One of the bleak aspects of UK choices is shown as a graph...
47. ### COVID About the protein shape of Covid-19

hello i came across an old article about crystalline shape of AEC2 receptor that is been some how associated with covid-19 my question dose knowing the crystalline profile of protein receptors some how can help with finding a better aid against this kind of outbreaks and how crystalline...
48. ### Starship Hull Shape Analysis: Discuss the Reality of Sci-Fi

Using real science we can extrapolate what hull shapes could be used, assuming we actually did have high thrust constant acceleration drives (we don't because it requires energy/mass ratios that tend to cancel each other out). So what shapes? Pill capsules are ideal for crewed vessels. Even...
49. ### Average current around a magnetic loop that changes its shape

To find out what the induced loop current was i used the formula: V=R×I To find out what the value of V was i used the formula that links electromotive force (fem) to angular speed: Fem=ω×B×A The only thing that's missing is the loops area but considering that it's a semicircle and that the...
50. ### Timoshenko Beam Theory (Violin String Shape Functions)

Homework Statement:: Violin String Shape Functions Homework Equations:: Violin String Shape Functions Hello, Is anyone working on violin string shape functions(Timoshenko Beam Theory)? It would be really helpful to my research if we share our knowledge on this topic. Thank you