Body Definition and 1000 Threads

  1. C

    Problem on kinematics of body falling from space

    Problem goes like this.. body falls toward a planet with acceleration of -g0*R^2/s^2. where R is the radius of planet 4000 miles, g0 is 30 ft/s^2, s is the distance of the body from the planets center. the initial distance of the body from the surface is 400 miles. find the impact velocity...
  2. T

    What Forces Are Acting on a Man Climbing an Incline?

    Homework Statement Draw a free body diagram of the incline. Build the free body diagram of the man. Which is the force which makes the man to go up the incline? http://imagizer.imageshack.us/v2/800x600q90/46/t92m.png Homework Equations Newton's 2º Law The Attempt at a Solution...
  3. D

    Body decays in a microbe-free environment?

    Hi! I'm a science fiction writer and need to know if a body would decay in a microbe-free environment. I have a killer running loose on a space station (far future). He kills and leaves a body in a secluded area. After a couple months, would the body have decayed? To what extent? Thanks for the...
  4. C

    Two body decay particle distribution and its Lorentz transformation

    For two-body decay ##A\rightarrow B+C##, if A is polarized, it is clear that we have: ##\frac{dN}{d\Omega}\propto 1+\alpha \cos\theta^*##, for final particle distribution. where, ##\theta^*## is the angle between the final particle's momentum ##p^*## and the polarization vector of ##A## in the...
  5. I

    Geometry problem (angle of body diagonal of a cube)

    refer to the following image so consider the angle of the yellow theta on the top left. this is 45*. if we fix one side of both red lines at the blue circles, and we slide the other end along the green side of the cube, ie just think of the green lines as rails for the red lines to slide...
  6. C

    Angular and linear velocity of a rigid body given a force.

    Hello, I'm trying to prove a simulation of mine is working correctly. the simulation has a cube of sides 1, mass 1 and c.o.m. position at (0,0,0.5) ie sitting on the xy plane. i have a force along the x-axis of 10. Is there anyway given those two, that i can work out the resulting ω and v of...
  7. A

    Angular velocity of rigid body

    Dear All, i was reading a book in which it is written that if a rigid body have both rotational(with angular velocity 'w' about its center of mass)and translation(with velocity 'v' of center of mass) motion then the whole motion can be treated as an equivalent motion of pure rotation about...
  8. M

    2D Rigid Body Dynamics - Newtonian Equaitons of Motion

    Homework Statement In the diagram attached a bar weighs 500 kg and is a 2D plane rigid body with mass centre at G. At the instant shown, the bar is moving horizontally at but reducing speed, causing horizontal deceleration as shown by vector a=-7i m/s2. At the same time, the bar is being...
  9. R

    Statics Rigid Body Equilibrium Problem

    Homework Statement The given force F is equal to 5000N,γ=〖30〗^o and α=〖15〗^o. The moment on member 4 is to be found. The geometry of the structure was worked out separately. Homework Equations To solve the problem I tried to use the Equilibrium equations which state that...
  10. C

    Can anyone help me check my free body diagram for mobile crane

    Homework Statement https://www.icloud.com/photostream/#AE5oqs3qHTNWQ;B21C49F3-02FB-4EA3-8CE5-D1E2C1FA7C49 Homework Equations The Attempt at a Solution https://www.icloud.com/photostream/#AE5oqs3qHTNWQ;A55D9431-FD6D-4884-9AFC-C4D7C8E39AF1
  11. A

    Questions about entropy, normal force, and the human body

    Greetings folks, I'm new to this forum and to physics in general so apologies if I come off like a greenhorn or if I am posting these questions in the wrong place. I have an Arts background and have never really "gotten" science, but my interest in post-Enlightenment philosophy has led me to a...
  12. Ascendant78

    Escape energy required for an orbiting body?

    My current level of knowledge is based on Physics I and my own readings, so bear with me if this is something relatively simple that I'm overlooking... Anyway, my question is regarding the energy required for an orbiting body to escape orbit? I understand the formula of escape velocity where...
  13. L

    Falling Body Equation: Derivation & Meaning

    Hello, I don't think I really understand the derivation of an equation of motion for a falling body under the force of Earth's gravity... I'm a little ashamed by this. I haven't been able to find someone asking quite the same question as I am about to ask. I completely understand that the...
  14. L

    Understanding Relativistic Velocities in a Simple Two Body System

    Hello, Recently I've been researching how to add velocities in a relativistic way, very interesting stuff. But every website I read uses a three body system to explain it. Object A relative to object B and object B relative to object C. I've spent a few hours looking and this is the only...
  15. GeorgeDishman

    Gravitational time dilation for a spherical body of finite radius

    I am considering the gravitational time dilation at the centre of a spherical, non-rotating body (such as the Earth). The usual formula for gravitational time dilation is √(1-r_s/r) where r_s is the Schwarzschild Radius and r is the radius of the clock compared to one at infinity, however, this...
  16. K

    Does rotation of rigid body need a couple or only 1 force is sufficien

    Hi all, Suppose we go in space where no gravity and friction exists. If there is a bar, in say - horizontal plane and we apply a force at one end of the bar, in this plane and perpendicular to the bar. Will that bar rotate and translate or it will only undergo pure translational motion...
  17. C

    Body sliding down an accelerating hemisphere

    We have a frictionless hemisphere M,of a radius R and a body m on the top of it.We give to the hemisphere a horizontal constant acceleration W and consequently the body begins to slide down the accelerating hemisphere.What is the relative velocity of the body in respect to the hemisphere when...
  18. T

    Codes and Standards relevant to district plumbing (see body )

    Hey guys , I've been searching for the codes / standards relevant to District plumbing (Road drainage , District Drainage , District water supply systems ) . Thank You for any help .
  19. K

    What would happen to a human body exposed to space without a spacesuit?

    I always wonder about our human body in space without any suits. I don't know exactly what happens but i want to know which has been a interesting question to me right from my past. What will happen when a human body is exposed to space without any space suits?
  20. P

    Center of gravity of an orbitting body not at center of gravity

    It just occurred to me that in the right gravitational field, say, in a low orbit 100 km from the core of a neutron star with a mass equal to that of the sun, an orbiting object's center of gravity is somewhat noticeably displaced from its center of mass. Specifically, 1 meter closer to the...
  21. O

    Derivation for black body radiation. What is the 2 bout?

    $${\rho}({\lambda}) d{\lambda}=E({\lambda})*f({E(\lambda}))*D({\lambda})d{\lambda}$$ $${\rho}({\lambda}) d{\lambda}$$ is density of radiative energy, $$E({\lambda})= k_BT$$ is the energy of an atom vibrate in 3D, $$f({E(\lambda}))=1$$ is the probability distribution. Equals to 1 because we...
  22. U

    Angular acceleration, rigid body

    Homework Statement A circular disk with the mass m and radius r is hanging from two ropes with length l when suddenly the rope ED snaps. For this moment, find: a, The angular acceleration for the rope OB, the angular acceleration for the disk b, The force T acting in OB The Attempt at...
  23. P

    Finding the friction force for a rotating body

    Homework Statement A solid cylinder is dragged over a surface by a constant force F that has an angle θ with horizontal. It rolls without friction around its symmetrical axis. The mass is M and radius is R and moment of inertia is I=\frac{1}{2}MR^2 The cylinder rolls on the surface without...
  24. K

    Measuring size of a body cavity

    I have to measure the size of a cavity of a animal body(s). What is more important I need to measure it on several bodies and compare the results. The cavity is small and contains liquid. That liquid can be extracted and that sets the volume of cavity to 0. It's important to note that the...
  25. C

    What Is the Role of Point D in a Body Diagram and Moment Equilibrium?

    Homework Statement Homework Equations M=FA Equlibrium condition= net Fy=0 net Fx = 0 Total Moment=0 The Attempt at a Solution I need help with the body diagrem The D circle thing is what? is that a roller?
  26. P

    Discover How to Select Internal Forces for Free Body Diagrams

    Homework Statement http://postimg.org/image/4lvunjeoz/ Solution: http://postimg.org/image/v1d7gilef/ When you have to calculate the internal forces at a point, how do you decide which forces are included in the free body diagram? For D, why isn't the rectangular bit of the distributed load...
  27. M

    Falling: How Our Body Absorbs Force & Reducing Impact

    How does our body absorb the force from falling? And if we roll or bend our knees while landing why is the force felt by our body less? Can somebody explain?
  28. R

    Motion of a body - conveyor/catapult/trebuchet design

    Hello All, I posted this same question to the classical physics forum - but I'm reckoning it's more ideally suited for a Mechanical Engineer: I'm currently working through a scenario in which the following occurs: An object of mass M1 (kg) approaches a rotating wheel at a speed of S1...
  29. Superposed_Cat

    Percentage water human body 90? 70? 53?

    Hi, every time I hear any website/TV program/person mention the percentage water composition of the human body it varies tremendously. 90,80,85,70,53. What is it? any help appreciated. Thanks
  30. AakashPandita

    Rigid Body Rotation: Axis Points Stationary?

    In rotation motion do points through which the axis passes also rotate or are they stationary?
  31. K

    Confused about the speed of a point on a rotating body

    Homework Statement The system consists of a 20-lb disk A, 4lb slender rod BC, and a 1-lb smooth collar C. If the disk rolls without slipping, determine the velocity of the collar at the instant theta=30 degrees. The system is released from rest when theta= 45 degrees. Homework Equations v=wr...
  32. Dotini

    Odd Body in Asteroid Belt with 6 Tails

    http://www.nasa.gov/content/goddard/hubble-sees-asteroid-spouting-six-comet-like-tails/#.UnvGoHemYRc Hubble photos http://www.nasa.gov/press/2013/november/nasas-hubble-sees-asteroid-spouting-six-comet-like-tails/ NASA press release
  33. F

    Inertia - Moments of Inertia of a rigid body (different axes)

    Inertia -- Moments of Inertia of a rigid body (different axes) Here is the problem http://imgur.com/pL6Bdgw So I missed class today because I was studying for a genetics test. I don't need the answer or anything but I was wondering what the general rule for inertia that I would use for...
  34. M

    Pulsar Orbiting another body, doppler shifted pulse rate problem

    Hey all, new to the forum. Had a tough question that I was trying to work out about an orbiting pulsar and the doppler shifted pulse period. So, if we have a pulsar orbiting some central object in circular orbit, with a constant orbital velocity v, and a pulse period of P_0, how can we write...
  35. J

    Force Body Diagram - Running: 115 lbs Weight

    This may be a stupid question, but could any of you help me with the force body diagram of a person running? Before the foot hits the ground, once the foot hits the ground, and after the foot hits the ground? I'm having trouble trying to figure out what forces are being applied to the person...
  36. J

    Force Body Diagrams: Solving Foot Movement Confusion

    Hello, I have been assigned a project to find a device to improve on, and one of the tasks is to create a force body diagram. I have a little bit of confusion when it comes to drawing it because if I'm writing the paper on shoes, and how it improves the movement of the feet, how will the free...
  37. A

    Drag Force on a Streamlined Body

    Hi, I know that the drag force on an object: Fd= 1/2 . ρ . v^2 . Cd . A where A is the reference area. But in the case of a streamlined body, I don't know what will be taken as the reference area. Should it be the largest cross-sectional area of the body?
  38. E

    What would happen to an earth sized body of water?

    Assuming no other compounds are initially present, what would happen to a body of Earth's mass, orbiting the sun at Earth's distance and speed, which is entirely composed of water? Assume that it just blinks into existence, and initially all the water molecules are arranged in a liquid sphere...
  39. R

    What will happen when a body is equally dense as the liquid?

    I am studying Floatation in school and I have some doubts. I get that if an object is denser than the liquid its placed on, it will sink, and if it is less dense then it floats. But what happens when the density of both (the object and the liquid) are same? Will it float or sink? My notes say...
  40. P

    Solving Free Body Diagrams Homework

    Homework Statement http://postimg.org/image/i7phx5pp1/ Im trying to draw an FBD for this, but I don't know how the treat the distributed load or what forces the thing at E contributes. Is it some kind of support? For the distributed load, I don't know what part of it the 800N/m and...
  41. S

    Calculate volume of body T between planes

    Homework Statement Calculate the volume of a body given by plane ##z=0## and ##z=1## and ##x^2+y^2+z^2=4##. Homework Equations ##detJ=r^2sin \theta## for spherical coordinates The Attempt at a Solution ##V=\iiint_{T}^{}dV=\int_{0}^{2\pi }d\varphi \int_{0}^{1}dz\int_{\theta...
  42. F

    Solving Free Body Diagrams with 1.9kg Object & F1=5, F2=2

    1. The question I'm struggling on has been answered on here before but with different values. Here is the link to the question https://www.physicsforums.com/showthread.php?t=344213 but on mine I have a 1.9kg object and F1=5 and F2=2. I figured out that the Y components are 0 for both of...
  43. H

    Archived Can You Solve This Two-Body Dynamics Problem?

    Homework Statement Two blocks are stack on each other. The lower block has a mass of 6.8kg and μs=0.34 with the floor. The top block has a mass of 3.4kg and μs=0.65 between the two blocks. A force of 18N is being applied to the top box to the left. What maximum force can be applied to the...
  44. B

    What is axial rigid body motion?

    What is axial rigid body motion? Is it along Z-axis?
  45. L

    Rigid Body Kinetics: Find Reaction Force at A

    Homework Statement As the picture says, we are trying to find the reaction force on the bearing at A: We are given: M(block) = 26.1kg M(bar) = 8.7kg L(bar) = 1.8m V(block) = 6.2m/s Homework Equations What I have attempted the solution with are: ƩF = ma ƩM = Iα I0 = (m*L^2)/12...
  46. G

    Rigid Body Kinetics: Angular Acceleration of Rod w/ Friction Torque

    Homework Statement A long slender rod has a mass of 0.66 kg and a length of 648.0 mm. The friction torque at the hinge is 0.41 Nm. What is the angular acceleration of the rod when it is 38 degrees below the horizontal? Homework Equations The Attempt at a Solution Torque =...
  47. M

    Calculating Kinetic Energy of Cylinder with Clamped End

    Hi All, I have a very simple question on a calculation, I would not doubt it correctness if it were not for the fact I am told by a colleague it is wrong, and I cannot see why (good job college times are gone). We have a cylinder of length L, density $$\rho$$ constant along the cylinder, one...
  48. T

    Body thrown at angle to the horizon taking into account air resistance

    Hi every body! I'm a new guy here, and want to applologize for my Not perfect English. From the name of the topic you can understand what 'm trying to do here. ok here is an exercise: We have tennis ball m=57gr. and diameter of the ball D=6.7sm. from the start point coordinates Xo=0 & Yo=0.3m...
  49. B

    Why Do Some People Conduct Electricity and Others Don't?

    I wasn't sure whether to post this question in biology or physics. I'm stumped on a couple experiments. Here are the basic experiments. I have people wash their hands and dry them off and then hold onto the probes of a volt meter. To my surprise some people give a reading as high as...
  50. M

    Which elements of the human body are found elsewhere?

    Carbon (18%) Hydrogen (10%) Nitrogen (3%) Calcium (1.5%) Phosphorus (1.0%) Potassium (0.35%) Sulfur (0.25%) Sodium (0.15%) Magnesium (0.05%) Copper, Zinc, Selenium, Molybdenum, Fluorine, Chlorine, Iodine, Manganese, Cobalt, Iron (0.70%) Lithium, Strontium, Aluminum, Silicon, Lead...
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