Rod Definition and 1000 Threads

  1. T

    Heat in a Rod Fundamental Solution

    Homework Statement The Attempt at a Solution So I know that I must have boundary conditions u(0,t) = 0 and ux(L,t) = 0. My textbook recommends reducing the given boundary conditions to homogeneous ones by subtracting the steady state solution. But, I thought these were already...
  2. jim mcnamara

    Lubricant for nylon rod in iron tube

    This is way outside my area. I have a 4" long 1/2" D. rod of 6/6 nylon, inside a mild steel tube. The application is all-weather. Length of rod travel is .70 to .75 inch. Light use, 20-50 actions per day. The application is an oddball latch release lever. Nylon was chosen because of cost...
  3. T

    Trying to improve heat flow through a rod by changing its shape.

    Hi all, I have a mostly theoretical question here. I have a copper rod approximately 2cm in diameter and 3cm tall. It is fit snugly inside a much taller cylinder. Heat enters through the base of the copper rod and exits through the sides into the tall cylinder. I need to improve conduction...
  4. S

    Angular acceleration and Torque when rod reaches vertical position?

    Angular acceleration and Torque when rod reaches vertical position?? A rod (mass 1.30 kg, length .670 m) attached to a frictionless axis is released from rest in the horizontal position. What is the magnitude of the torque and angular acceleration when the rod has reached the vertical...
  5. W

    What techniques can be used to analyze a rod rotating about the edge of a table?

    A uniform rod of length 4x is rotating about the edge O of the table. (The rod does not fall off the table.) The centre of mass G of the rod is distance x away from O. The rod is making an angle θ with the horizontal. The only forces present are the weight W of the rod, the normal reaction N...
  6. N

    Thermal Expansion - Both rule and rod

    Homework Statement A brass rod's length is measured at 20.0 degrees C with a metre steel rule. The length of the rod is determined to be 0.5260 m. The measurement is repeated at 61.6 degrees C. Taking into account the expansion of the rule and rod, what is the new measured length in metres...
  7. M

    Emf in a conducting rod moving away from a wire with current I

    Homework Statement A conducting rod of length l moves with a constant speed v perpendicular to an infinately long, straight wire carrying a current I. What is the emf generated between the ends of the rod when it is a perpendicular distance r from the wire? Homework Equations no idea...
  8. D

    Finding stress energy tensor of a rod under tension

    I am given a rod with mass per unit length \mu , cross sectional area A, and under a tension F. I am also told that the tension F is uniform over the cross sectional area A. Find the stress energy tensor inside the rod. I know that for the stress energy tensor T^{00} gives the energy...
  9. D

    Find the force of the rod on the point charge

    Homework Statement A rod of length L and total charge Q is a distance D from a point charge q which lies along the perpendicular bisector of the rod. Find the force of the rod on the point charge Homework Equations E = ∫ dE dq = λdx F = qE The Attempt at a Solution I'm...
  10. A

    Motion of a rod on another rod of same mass.

    Homework Statement A perfectly rough rod is gently placed with one end upon another rod of equal mass and in the same vertical plane, moving with the velocity √2gc on a smooth table. If the initial inclination of the first rod to the horizon be α, and its length 2a, shew that it will just...
  11. G

    Induced EMF on a moving rod next to a line of current.

    Homework Statement I'm currently reviewing some of the old E&M material that I haven't seen in a while and have gotten stuck on this problem. I'm sure I'm just making a simple mistake but I can't seem to make any headway. Here's the problem: Figure 35-32 shows a copper rod moving with...
  12. T

    Max Angle Rod Rotates when Hit w/ Ball

    EDIT: Title should say "To what maximum angle, measured from vertical, does the rod rotate when hit will a ball?" Did not see that it had cut off. Sorry. Homework Statement A 78 g, 40-cm-long rod hangs vertically on a frictionless, horizontal axle passing through its center. A 14 g ball of...
  13. J

    Finding the gravitational field of a rod

    Homework Statement A homogeneous rod with even thickness has mass M and length L. a) Find the gravitational field g(x) at a distance x from the rod on an axis normal to the midpoint of the rod. b) Find the gravitational field g(y) at a distance y from the rod's midpoint on an axis through...
  14. S

    Period of rod connected to spring

    Homework Statement A spring has one of its end connected to the ceiling and the other end connected to the end of horizontal rod. The rod is free to rotate in xy-plane about its vertical axis. The mass of the rod is 0.6 kg and the spring constant is 2000 Nm. If the rod is displaced and...
  15. C

    Moment of Inertia of an Infinite Rod with Non-Uniform Density?

    Homework Statement A thin rod extends along the x-axis from x= +b to infinity. It has a non-uniform linear mass density of A/x^{4} where A is a constant with units of kg m3. Calculate the moment of inertia of the rod for rotation about the origin. Homework Equations The Attempt at a Solution...
  16. H

    Conservation of Angular Momentum - Two ants on a massless rod

    Homework Statement This is a problem about angular momentum and torque from the physics textbook Don't Panic Volume I. Attached is a screenshot of the problem. Homework Equations L = mr2ω The Attempt at a Solution The angular momentum must be conserved to keep ω constant...
  17. T

    Copper rod vs. bundle of wires in a magnetic field

    I was wondering what the difference in current is if there is one when you have a bundle of copper wire passing through alternating magnetic fields verses a solid copper rod of the same diameter. Will the rod have more current because there is more copper? Would it have less because more copper...
  18. D

    Rod rotational inertia - axis at end of rod

    I want to ask why a rod's rotational inertia with rotational axis at its end is not 1/2 mR2 but 1/3 mR2?
  19. K

    Real formula for gamma(deformation) in torsion of a rod?

    Okay, so I'm studying for a Mechanics of Materials final at the moment, and I am reviewing the chapter on torsion. I was reading through the given formulae, and I stumbled across one that I could not fully visualize (or simplify): the formula for gamma. Based on my understanding and from...
  20. A

    Pivoted rod - impulse applied so no horizontal force on pivot

    Homework Statement There is a rod of length L pivoted on one end. It is originally at rest horizontally then released. When vertical, an impulse is applied to bring the rod to rest. Throughout the question I have worked out I = 1/3 mL^2 w= √(3g/L) at the vertical position and an...
  21. E

    Coplanar forces equilibrium- a rod in a sphere

    Homework Statement A rod whose CG divides it into two portions of length a and b rests inside a smooth sphere in a position inclined to the angle θ to the horizontal. If 2α is the angle it subtends at the centre of the sphere, prove that tanθ= (b-a)/(b+a) tanα Picture is attached...
  22. S

    Velocity of CM of Rod if struck below CM ?

    Let's say there is an elastic collision b/t a particle and a rod. The rod (initially motionless) is struck by the particle at some distance below its CM and particle comes to rest. So we have an elastic collision where v of particle is completely transferred to rod. BUT how do I analyze...
  23. T

    A rod hanging by two strings find theta

    Homework Statement A uniform rod is supported by two strings. The string on the left hand side is horizontal. The string on the right hand side is at 30 degrees with respect to a straight line going from the end of the bar to the ceiling. If you had a straight line going from the end of the...
  24. C

    Centre of mass problem; Non uniform rod with ball weights

    Homework Statement A non uniform rod of length L=1m and linear mass density: λ(x)=λo(1-(x/2L)) with λo=1Kg/m. It is supported at it's midpoint and initially tips over so that it's left end lies on the ground. Part a: Find the position of the centre of mass along the rod when it is in it's...
  25. fluidistic

    Potential of an infinite rod using Green's function

    Homework Statement Same problem as in https://www.physicsforums.com/showthread.php?t=589704 but instead of a spherical shape, consider an infinite line of constant charge density \lambda _0. Homework Equations Given in the link. The Attempt at a Solution I assume Phi will be the...
  26. L

    Moment of a rod of varying thickness

    Homework Statement Q A cylindrical steel shaft of radius 2cm and long is turned upside down on a lathe to one half its radius for a distance of 20cm from one end find the distance of its centre of gravity from the thicker end.? Homework Equations The Attempt at a Solution
  27. S

    How Fast Does the Tip and Center of Mass of a Falling Rod Travel?

    A long, thin rod of mass 9.65 kg and length 10.18 cm is standing stright up on a table. Its lower end rotates on a frictionless pivot. A very slight push causes the rod to fall over. What is the speed of the tip of the rod as it hits table? What is speed of center of mass of rod? 1/2 m...
  28. FeDeX_LaTeX

    Potential Energy of System (Uniform Rod and String)

    Homework Statement http://desmond.imageshack.us/Himg339/scaled.php?server=339&filename=53171696.jpg&res=medium Homework Equations GPE = mgh, EPE = λx^2 / 2l The Attempt at a Solution I'm taking the horizontal line through A as the zero-level for potential energy. Clearly, the...
  29. H

    Forces Acting on a Rod in Empty Space: Motion & Kinetic Energy

    Suppose I have a metal rod in empty space with a uniform mass distribution. Suppose a force acts perpendicular to the rod at some distance R from the rod's centre of mass over some time Δt. There are no other forces acting on the rod. (1) What type of motion will the rod have over Δt? Will...
  30. N

    Determine the maximum tension in the pendulum rod

    Homework Statement A clock’s pendulum is 60 cm long with a bob at the end of mass 500 g. Determine the maximum tension in the pendulum rod when the bob is b) swinging at a speed of 2.4 m/s Homework Equations v^2 / r = ac The Attempt at a Solution 9.8m/s^2 = g (2.4)^2 / 0.6 = 9.6m/s^2...
  31. B

    Panel Structure vs. Solid Rod Structure

    Hi Everyone, I have a question about panel vs. solid rod structures. Assume a two cubes of equal dimension and weight. Cube 1 is made of panels, ie. a hollow cube. Cube 2 is made with solid rod Material is linear elastic Which would be stiffer? I think the panel...
  32. Y

    Deflection of light through a relativistic glass rod.

    Let us say we have a very long glass that has a uniform square cross section. Its long axis is aligned with the x axis. A beam of light is directed along the y-axis such that it is normal to the side of the glass rod's side surface. When the rod is stationary wrt to the observer we would expect...
  33. B

    How to stop leak of water tank while steel rod enters and exits?

    Hi: I have a tank of water (of plastic) of about 2 x 4 feet. I want a steal rod (with a ball of 5 inch at end of rod) to be cross that water tank from center, but water should not leak from tank (rod will enter from right and exit from left of tank) You can get more idea from image that...
  34. A

    Three forces in equilibrium. Uniform rod

    Homework Statement A uniform rod AB of weight W rests in equilibrium with the end A in contact with a smooth vertical wall and the end B in contact with a smooth plane inclined at 45 to the wall. Find the reactions at A and B in terms of W. Homework Equations The sum of the three forces equal...
  35. H

    Why Is Potential Higher at the Positive End of a Conducting Rod?

    When an induced emf is created in a conducting rod why is the resulting potential higher at the positive end of the rod? Since the electrons accumulate at the negative end of the rod then wouldn't this be the higher potential instead? Don't negative charges flow from lower to higher potential?
  36. A

    Potential of a non-uniform charged rod

    Homework Statement A thin charged rod of length L lies along the x-axis as shown in the diagram below. The charge on the rod is distributed with a density of λ= c x (C /m) where c is a constant. What is the potential at a point (0,y)? (Your answer should be in terms k, c, L, and y). See...
  37. B

    Analyzing Rotational Motion of Massless Rod and Object

    Homework Statement A mass-less rod of length, Ls, is rotating clockwise about a point, P1 in the horizontal plane. Attached by a cable of length, Ls, to the end of the rod and at angle θ is an object of mass, M. Starting at rest and then with the rod having and angular acceleration α, describe...
  38. F

    Does a Yank of 100 Newton Meters Affect a 5 Kg Rod?

    So Imagine that a force of 100 N is being applied continuously on face of 5 kg cylindrical rod (1 light year across) causing it to accelerate at 20 m/s^2. If the force was abruptly removed would the rod continue to accelerate a noticeable period of time before coming to a halt? The density of...
  39. C

    Relativistic rod moving in two directions.

    Homework Statement A rigid rod has rest length L0 and moves relative to a system S' for which it's coordinates is x'=0, y' = b-ut', z' = 0. In this reference frame the rod is at all times parallel with the x'-axis. a) A point (A) on the rod is measured to be a distance= a, away from x' = 0...
  40. P

    Gravitational Potential Due to a Thin Rod of Varying Density.

    Homework Statement GRAVITATIONAL POTENTIAL AND FIELD DUE TO A “THIN” ROD A thin rod of length L lies along the +y-axis, with one end at the origin (see diagram). Assume: • The rod has length only- no thickness in other directions. • The density of the rod increases proportionally to...
  41. M

    Calculating Mss of a Rod using Integration

    Homework Statement Let a rod with length L and constant cross-sectional area A have the density ρ(x) = ρ((3.x^2 + 2.x.L)/L^2) 0 ≤ x ≤ L where x is the distance from one end of the rod and ρ0 is a real constant. (a) Find the total mass M of the rod. (b) Find the x-coordinate xc of...
  42. Y

    How is the field inside a rod magnet in the presence of ferro magnetic material?

    For a rod magnet, how is the field inside the rod change if another piece of ferro magnetic material is being brought close to one end of the rod? Does the presence of ferro magnetic material increase the field strength inside the rod magnet?
  43. A

    Find Instantaneous Center of Rotation for Impulse on a Rod

    Homework Statement Suppose there is a rod on a friction less horizontal plane and an impulse "J" is given to it at a distance "x" from its center. Using this data I have to find out the instantaneous center of rotation. The Attempt at a Solution By impulse-momentum theorem, J =...
  44. I

    Balance of the cylinder on the rod

    It is told, that all homework-like threads should be posted there. So, here I go. Imagine such a situation: there is a vertical rod and a cylinder, with the hole diameter sightly larger than the diameter of rod. There is also a second rod, attached to the cylinder perpendicularly. There is a...
  45. I

    Balance of the cylinder on the rod

    Imagine such a situation: there is a vertical rod and a cylinder, with the hole diameter sightly larger than the diameter of rod. There is also a second rod, attached to the cylinder perpendicularly. There is a friction between the main rod and the cylinder. It is known, that if we put a...
  46. C

    How Do You Calculate the Electric Field at a Point Near a Charged Thin Rod?

    Homework Statement Thin Rod - Length = 5.0cm - Total Charge = 8.4 nc Calculate the electric field at point p, 3cm away. Homework Equations E = (1/4∏ε) * (q/r^2) λ = Q/L The Attempt at a Solution I think you treat the rod as a series of point charges, meaning the electric...
  47. D

    What is the required force to bend a rod into a horseshoe shape?

    I need to calculate the force necessary to bend a rod 180 degrees around a radius of 1.75 meters. Basically bending the rod into a horseshoe. I have looked at the simple bending calculations and I am sure this must be similar to those but I do not see anything for a constant radius bend. Any...
  48. teroenza

    Gravitational Force Due to Infinitely Long Rod

    Homework Statement Infinitely long rod with the z axis at its center. The rod has a uniform mass per unit length \mu. Find the gravitational force vector F on a mass m, at a distance \rho from the z axis. Homework Equations F=-G*(M*m)/R^2 (times radial unit vector rhat for the vector form)The...
  49. R

    Rotation of Rod Homework: Max Angle, Motion Analysis

    Homework Statement A uniform thin rod with mass M and length L nailed by frictionless pivot can swing freely on the wall as shown in Fig. The pivot locates at the distance L/4 from the bottom and stops inside. The velocity of the bullet before hitting the rod is v. (a) Compute the max. angle...
  50. S

    A steel rod and an iron rod is placed inside an ac current soleoid

    What happens? I think nothing should happen since the rods will not get magnetised at all due to the ac current.. Thanks for the help!
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