Position Definition and 1000 Threads

The missionary position or man-on-top position is a sex position in which, generally, a woman lies on her back and a man lies on top of her while they face each other and engage in vaginal intercourse. The position may also be used for other sexual activity, such as anal sex. It is commonly associated with heterosexual sexual activity, but is also used by same-sex couples.The missionary position is the most common sex position, but is not regarded as the most favoured one. It may involve sexual penetration or non-penetrative sex (for example, intercrural sex), and its penile-vaginal aspect is an example of ventro-ventral (front-to-front) reproductive activity. Variations of the position allow varying degrees of clitoral stimulation, depth of penetration, participation on the part of the woman, and the likelihood and speed of orgasm.
The missionary position is often preferred by couples who enjoy the romantic aspects of ample skin-to-skin contact and opportunities to look into each other's eyes and kiss and caress each other. The position is also believed to be a good position for reproduction. During sexual activity, the missionary position allows the man to control the rhythm and depth of pelvic thrusting. It is also possible for the woman to thrust against him by moving her hips or pushing her feet against the bed, or squeeze him closer with her arms or legs. The position is less suitable for late stages of pregnancy, or when it is desired for the woman to have greater control over rhythm and depth of penetration.

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  1. J

    Position vector in curvilinear coordinates

    The position vector ##\vec{r}## in cartesian coordinates is: ##\vec{r} = x \hat{x} + y \hat{y}##, in polar coordinates is: ##\vec{r} = r \hat{r}##. But, given a curve s in somewhere of plane, with tangent unit vector ##\hat{t}## and normal unit vector ##\hat{n}## along of s, exist a definition...
  2. nicolauslamsiu

    Equilibrium Position: How Water Affects System

    I want to ask how will the equilibrium position of the system change if water is added to the system?
  3. S

    Advice on obtaining an actuarial position (entry level)

    I'm in the process of job hunting right now and I'm trying to obtain an actuarial position. Looking to hear if any actuaries here have any suggestions or tips on how to increase my chances. Right now, I"m just looking through job searching sites like indeed and monster, and also going to...
  4. S

    Would The Position of the Center of Mass Change Position?

    Take a uniform density bar in space for example. Would the center of mass move if the bar was struck at the very tip perpendicularly by some weight? If so, please explain.
  5. R

    Orbital simulation - Calculate object position over time in a 2d plane

    Hi Im busy creating an application to simulation a rocket in orbit. I am having trouble as the results I am getting are incorrect. Could someone please check if I am using the correct method as stated below. Everything works on a 2d plane, and has a x and y coordinate and a x and y...
  6. E

    Normalizing a wave function and calculating probability of position

    Forgive me if this goes in elementary physics, but I think since it's an upper level undergrad class Homework Statement A state of a particle bounded by infinite potential walls at x=0 and x=L is described by a wave function \psi = 1\phi_1 + 2\phi_2 where \phi_i are the stationary states. a)...
  7. J

    Derive conservation of center of mass position

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  8. JonnyMaddox

    Lagrangian/Hamiltonian problems and find the position

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  9. D

    Position of spot in oscilloscope

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  10. A

    Calculate how far the spring is stretched from its position?

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  11. U

    OPTICS: finding image position using matrix methods

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  12. T

    How to find the at rest position of a particle when trig functions

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  13. atyy

    Joint distribution of position and momentum

    In quantum mechanics, there doesn't seem to be a joint distribution of position and momentum. But in Bohmian mechanics there is. But Bohmian mechanics is quantum mechanics, so what is the error in my reasoning?
  14. C

    Finding velocity as a function of position, constant acceleration

    This isn't actually a homework question, it's for a vehicle safety project at work, but I think it fits in this forum. Homework Statement A truck is traveling down the road at 60 mph, and begins to decelerate at a rate of 0.8 g. I'd like to find the total distance it takes the truck to...
  15. V

    Calculate the z position of the particle as a function of time.

    1. A particle of mass m is suspended from the ceiling by a spring with constant K and relaxed length initial lo, whose mass is negligible. The particle is released at rest with the spring relaxed. Taking the Oz axis directed vertically downward, with the origin on the roof, calculate the z...
  16. B

    Stern Gerlach and Position Measurements

    Homework Statement Given the following stern-gerlach setup, find the probabilities for particles to arrive in detectors D1 and D2. SGx = Stern Gerlach in x direction, SGx = Stern Gerlach in z direction (sorry for terrible ascii drawing) |ψ> = a|+> + b|->, |ψ> is normalized. ..../D1...
  17. 7

    Regarding r and sign convention for Position vectors for moments

    Homework Statement The Attempt at a Solution I'm having trouble understanding how r1 = -1.5j and r2= r3 = 0. Can anyone make this a little clearer for me? I've spent quite a while trying to wrap my head around it but to no avail.
  18. B

    What Are the Steps to Analyzing a Position vs Time Graph?

    Homework Statement Position vs Time graph is given. It is a perfect parabola. So it has a quadratic equation Y: Ax^2+Bx+C that fits it perfectly. (a) Determine acceleration, initial velocity, initial position (b) Sketch a motion map (c) Sketch a v vs t graph My attempt: initial...
  19. S

    Position variables in the wave function

    I would like some clarification as to the mathematical and physical definitions of the position variables in the wave function. I often see that it is treated as a variable independent of time; this is utilized in the separation of variables technique. However, the Schrodinger equation implies...
  20. C

    MHB Change of Position: Word Question

    In a game of tug of war, your team changes -1 and 3/10 (-1.3) feet in position every 10 seconds. What is your change in position after 30 seconds? I said -3.9 but apparently was wrong. What am I missing? Thanks!
  21. M

    Find eccentricity of orbit given position and velocity

    Homework Statement Hey, I need to find whether an asteroid is in a "bound orbit" around the Sun. Furthermore, describe the shape of the orbit (elliptical or circular). The only information I have been given is its velocity and position at a random point. v_o=61m/s r_o=13.75AU=2.06E12m I also...
  22. Philosophaie

    Transform from one position to another.

    Homework Statement Using the Schwarzschild Metric and the Contravariant Position Vector 1x4 ##x^k## with 4 vector: $$x^{k'} = \left[ \begin {array}{c}r \\ \theta \\ \phi \\ t \end {array} \right]$$ where ##x^1## = r = 1 per unit distance ##x^2## = ##\theta## = 50 Degrees ##x^3##...
  23. C

    Temperature is inversely proportional to position away from center

    A metal sphere with center at origin has its temperature that is inversely proportional to the position from center. At point P(1,2,2) temperature is found to be 120 degrees What is the rate of temperature change in direction of Q(2,1,3)?
  24. D

    Charged particle final position equation

    Hello all, I am new to PF; this is my first post. I am currently taking a physics class on electricity and magnetism. I am trying to find an equation to calculate the final position of a charged particle p, given that there are n other particles. Known: + initial (positions and...
  25. N

    How Does the Hour Hand's Velocity and Acceleration Change from Noon to 6pm?

    Homework Statement What are a) average velocity and b) average acceleration of the tip of the 2.4cm long hour hand clock in the interval from noon to 6pm. Use unit vector to express, wth the x-axis pointing towards 3 an y-axis towards noon. Homework Equations The Attempt at a...
  26. J

    How position of quarks decide the type of elementey particles ?

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  27. Ascendant78

    Potential energy vs position graph w/ total mech. energy?

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  28. S

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  29. S

    Expectation value for a position measurement

    Homework Statement Given the wave function psi(x,0) = 3/5 sqrt(2/L) sin(xpi/L) + 4/5 sqrt(2/L) sin(5xpi/L) in an infinite potential well from 0 to L, what is the expectation value <x> and rms spread delta E = sqrt(<E^2>-<E>^2) Homework Equations <x> = integral from 0 to L of psi*xpsi dx...
  30. N

    Kinematics motion - Given position, find velocity and acceleration

    Kinematics motion -- Given position, find velocity and acceleration Homework Statement A particle's position as a function of time is given by xf = xi . sin wt, where xi and w are constants. a) Find expressions for velocity and acceleration. b) What are the maximum values of velocity...
  31. H

    Momentum operator as differentiation of position vector

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  32. N

    Does position operator have eigen wave function?

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  33. P

    Most probable position of electron in an infinitely deep square well

    Homework Statement An electron in an infinitely deep square well has a wave function that is given by http://postimg.org/image/s159u7ynt/ What are the most probable positions of the electron?The Attempt at a SolutionI got the values as L/6, L/2, 5L/6 by finding the x values that made the wave...
  34. KiNGGeexD

    Find velocity as a function of position x

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  35. KiNGGeexD

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  36. T

    Trying to triangulate position of rogue radio transmitter.

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  37. atyy

    Must position be continuous in Bohmian mechanics?

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  38. lonewolf219

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  39. U

    Prediction of electron position

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  40. R

    Find an equation for position vs time given potential vs position?

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  41. C

    What is the notation for the distance between two position vectors?

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  42. C

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  43. R

    What Are Durable Alternatives to Potentiometers for Electronic Throttle Systems?

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  44. E

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  45. T

    Various position functions from dx/dt

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  46. A

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  47. K

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  48. E

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  49. J

    Calculate position of the centre of a rigid bar

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  50. S

    What's the Difference Between a Position and a Position Vector?

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