1. R

    Taylor expansion, centered difference formula, third derivative

    Hi again. I'm preparing for a big exam next week and I'm having a little trouble with the attached derivation. Specifically, I have an extra 3/8 multiplicand and I'm not sure what to do with the O(h^3) error term. Sorry if this seems trivial but I haven't taken Physics for almost 40 years and we...
  2. H

    Expansion of Universe- Dark Energy, or Multiverse?

    First, I'd like to clarify that I'm in no way a physicist, not yet, anyway. I'm merely a young college student fascinated by all things..."big-picture" physics, for lack of a better word. As such, my scope is very narrow, and my understanding, limited. That being said, the following, "theory,"...
  3. H

    Expansion of Universe

    Moved to correct thread.
  4. Y

    Please explain the Taylor expansion in Radiation

    For retarded scalar potential of arbigtrary source around origin: Where r point to the field point where V is measured. And r' points to the source point. For r' << r : This next step is where I don't understand how the book do the Taylor expansion. I am going to type the exact word...
  5. R

    the accelerating expansion and inversive geometry

    I'm not sure this belongs in this forum, but here goes... In inversive geometry, as a point within a unit circle approaches the center of the circle, its inversion outside of the circle approaches infinity at the rate of x=r^2/y, which is an accelerating rate. (r is the unit circle...
  6. H

    Time taken for volume expansion

    A certain substance doubles its volume every minute.At 9.00am a small amount is placed in a container and at 10.00am the container just fills.What was the time at which the container was one quarter full ? (ans : 9.58am) Hmmm...I have no idea how to do this & I'm not even sure if this is a...
  7. F

    [SOLVED] Thermal Expansion

    A steel ball of diameter Lb = 4.194 cm is placed on a hole of diameter Lh = 4.089 cm on an aluminium plate. The initial temperature is T5 = 17.4 °C. What would be the minimum temperature so that the ball will fit through the hole if both are heated? The linear expansion coefficient for steel is...
  8. T

    Thermal Expansion

    A square brass plate, 8.00 cm on a side, has a hole cut into its center of area 4.90869 cm2 (at 20.3°C). The hole in the plate is to slide over a cylindrical steel shaft of cross-sectional area 4.91006 cm2 (also at 20.3°C) as shown in the figure below. To what temperature must the brass plate be...
  9. J

    Acceleration of Expansion Rate of Universe: Please Destroy my Theory

    First time poster. Cool site. When I heard that the expansion of the universe is accelerating, I wondered if it might be due to gravitational attraction between our universe and everything that surrounds our universe. I am sure that somebody thought of this and determined that it is...
  10. V

    Linear Expansion

    I wanted to determine the relationship between the temperature of an aluminium bar, and the expansion of this bar from room temperature (RT). I had temperature of the bar as the independant variable, then expansion from RT as the dependant variable (this simply meant measuring the heated...
  11. S

    Thermal expansion

    A rod is measured to be exactly 23.48 cm long using a steel ruler at a temperature of 20.2 degrees C. Both the rod and the ruler are placed in an oven with a temperature of 333 degrees C where the rod now measures 23.58 cm using the same ruler. What is the coefficient of thermal expansion for...
  12. S

    Expansion and volume

    Hi, I am just hoping to get something confirmed here really. If a fluid passes through an expansion valve, where it expands adiabatically, does the volume of the fluid decrease or increase? Thanks in advance. Sean