Specific Definition and 1000 Threads

  1. V

    Product of a specific sequence of prime number squares

    Here is a good question for maths enthusiasts. I really find this sum very tough. Any help, advice or guidance for this question will be greatly appreciated. find the product upto n terms (1+(1/2^2)) . (1+(1/3^2)) . (1+(1/5^2)) . (1+(1/7^2)) . (1+(1/11^2))...upto n terms Where the nth...
  2. S

    Can Specific Heat Capacity Be Negative? - Physical Meaning Explained

    Can the specific heat capacity be negative? Is there any substance for which i have to add heat to decrease its temperature? By the way,why specific heat capacity has the word "capacity" in it? Is there any physical significance to it or it is simply traditional(historical)?
  3. G

    U, V, and T: Internal Energy, Specific Volume, and Temperature

    u denotes internal energy; v denotes specific volume; T denotes temperature.
  4. R

    Specific heat of a heavy ion plasma

    I am surprised by the result when I estimate the specific heat of the plasma produced by heavy ion collisions in the LHC: C(plasma) ~= 2e5 J/(g-K) (Details below.) This is ~1e6 times greater than C(lead)=0.13 J/(g-K) (1). Did I make a mistake? If not, can the physics experts who read this...
  5. A

    Recombinant dna technology-[how are specific genes chosen]?

    Recombinant dna technology-[how are specific genes chosen]?? IN recombinant dna technology,certain segments of dna are removed from one organism and put in another.How are are specific portions of DNA removed from certain animals and fused into others?? More importantly,how do scientists know...
  6. F

    How can i determine Specific heat capacity of Water cpv if i know all variables

    How can i determine Specific heat capacity of Water cpv if i know all variables If i use this equation: [(mi1 + mi2 +mv)cpv + mg*cpg]dT/dt = H mi1 = mass 1 dT/dt = 0.05 cpg = 890 J/(kg*K) mi2 = mass 2 mv = mass 3 H = 300 W masses are arbitrary numbers Its cpv that...
  7. J

    Specific Heat Capacity of metal in water

    Homework Statement An unknown metal with C=3.6 Mass=150g Temp=160c is added to copper container(85g) filled with water(105g) both with an initial temp of 20c I have to find the final temp of water,container and metal Homework Equations none given but I assume it will be E=Cm(t1-t2)...
  8. N

    Specific heat capacity varies with temperature.

    Homework Statement Heating a .8 kg disk of iron from 20 C to 400 C, but the specific heat capacity changes from 456 at 20 C, to 615 at 400 C. It hints that I'm supposed to find the average to solve the equation. Homework Equations E = mC(dT) The Attempt at a Solution I have a...
  9. T

    Analytically solving ODEs with non-constant coefficients for a specific t

    Given an ODE in the form of f(t)y''+g(t)y'+h(t)y=0 If all I am looking for is the y(t) at a specific value of t and NOT the general solution, can I just plug in that value of t into the original ODE and then solve it analytically or is a numeric solution the only way?
  10. C

    What Force is Necessary to Submerge Mary in Fresh Water?

    What force is necessary to just barely submerge (push Mary under fresh water) Mary if her average specific gravity is 0.95 after taking a deep breath and her weight in air is 660 N? F=mg ; Force of buoyancy=ρgV; F=mg 660/9.8=mass of air mass of air=67.3 force of buoyancy= 67.3 x...
  11. M

    Very specific question on current draw from a dc power supply

    okay so I am just slightly confused about current and about how it is drawn from a power supply, so say we have a device that requires 5 volts and uses a max of 550 milliamps, and now let's say that the power supply used is rated at 5 volts, but 32 amps, does this mean that the power supply...
  12. C

    Chemistry Specific Rotation of Chiral Molecules

    Homework Statement Why may the specific rotation of a sample of (R)-(+)-limonene be less than the literature value of (R)-(+)-limonene. Assume that there are so (S) enantiomers present. Homework Equations The Attempt at a Solution There are no (S) enantiomers, but there are some...
  13. I

    Specific heat capacity question

    Homework Statement When a car brakes, an amount of thermal energy equal to 112500J is generated in the brake drums. If the mass of the brake drums is 28 kg and their specific heat capacity is 460.5 Jkg^-1K^-1? A piece of iron of mass 200g and temperature 300°C is dropped into 1.00kg of water...
  14. P

    Statement of Purpose - School Specific Info

    This is a common subject I'm sure, but for reasons unknown this information is difficult to find. I have written my statement of purpose, all that remains is to customize it to each institution that I am applying to. How did you handle this? Did you talk about faculty you think would be...
  15. E

    Schools Specific interests required for graduate school?

    Hi, I got my BS in Physics/Math in May, but left on a 1-2 year bike trip that is delaying my applying to graduate schools. I plan on applying next fall for admittance fall 2013. My question is: how necessary is it to have specific research interests when applying to graduate school? I am...
  16. 1

    Specific heat mixture, final temp, etc.

    Homework Statement The specific heat of lead is 0.03 cal/g*C. 300 grams of lead shot at 100* C is mixed with 100 grams of water at 70* C. What is the final temperature of the mixture if the container is insulated. Homework Equations The Attempt at a Solution Q1 = c1m1(Tf - 100)...
  17. V

    Newton Polynomials through Specific Points

    I have completed a difference table for 4 points, x0, x1, x2, x3 and found the third degree poly that goes through these four points. Now I need to know how to make the polynomial of second degree that interpolates x0, x2, and x3. Do I just need to remake the table for 3 points, now excluding...
  18. F

    Molar specific heat of an ideal gas

    Homework Statement A sample of a diatomic ideal gas has pressure P and volume V. When the gas is warmed, it's pressure triples and the it's volume doubles. This warming process includes two steps, the first at constant pressure and the second at constant volume. Determine the energy...
  19. T

    Steam at specific volume/pressure

    hi all! i'm trying to figure out how much water i need to heat and to what temperature, to end up with 1 cubic meter of steam at 70atm. i used the calculator found here: http://www.efunda.com/materials/water/steamtable_sat.cfm i punched in 70atm, and got the following data: Temperature...
  20. F

    Specific & Latent Heat - Heat required to turn water in Aluminum Tray -> Ice

    Specific & Latent Heat - Heat required to turn water in Aluminum Tray --> Ice Homework Statement 200 g Water (l) is contained in an Aluminum ice tray that has a mass of 340 g. Both is at 18°C. How much heat (Q) must be removed to turn the water into ice at -15°C? Aluminum mAl= 340g...
  21. F

    Specific rotation and its uncertainity.

    Two Work-Study students were hired to check and test the reproducibility of some new experiments and of the new polarimeter. Student 1 prepared three samples of the same resolved amine by repeating a resolution experiment three times. Student 2 performed three measurements of the specific...
  22. D

    How do you calculate the specific heat capacity of nickel?

    Homework Statement A 28.2 g sample of nickel is heated to 100 degrees C and placed in a coffee cup calorimeter containing 150g of water at a temperature of 13.5 degrees C. After the metal cools, the final temperature of the metal and water is 25 degrees C. Calculate the specific heat...
  23. D

    Specific Heat Capacity Question Mixture Q=MCdeltaT

    Homework Statement A mixture is made by adding 75g of an unknown liquid at a temperature of 25 degrees Celsius to 60g of water at a temperature of 90 degrees Celsius. The final temperature f the mixture is 65 degrees Celsius. Calculate the specific heat capacity of the liquid. What is the...
  24. N

    Heat Capacity v Specific heat capacity?

    Homework Statement what is the different in term of definition between Heat capacity and Specific heat capacity ? Homework Equations Q=mΔTC →C=Q/mΔT The Attempt at a Solution Specific heat capacity is the amount needed per unit mass of material so is a number independent of the...
  25. F

    How Much Heat is Needed to Vaporize Ethyl Alcohol from -50°C to Boiling Point?

    Homework Statement How much heat is required to change 1.75 L of Ethyl Alcohol (C2H6O) at -50.0°C to a gas at its boiling point? Ethyl Alcohol V = 1.75 L Ti = -50°C 46 g/mol density = 0.789 g/cm3 boiling point = 78°C specific heat (c)= 2400 J/kg*C° Heat of Vaporization (Lv) =...
  26. H

    Rolling ball down slope at specific time

    Homework Statement A uniform solid ball rolls down a slope. If the ball has a diameter of .5m and a mass of .1 kg find the following: The equation which describes the velocity of the ball at any time, given that it starts from rest. Homework Equations I've tried using energy...
  27. S

    Understanding Specific Heat Units (hg-C)

    Hopefully this is a really simple question to answer. A problem I have uses the following information: The specific heat of air = 1.05 kJ/hg-C. Does anyone know what the hg-C stands for? I know specific heat is usually expressed in terms of J/C, so this is confusing me.
  28. M

    Finding pairs of numbers that meet a specific criteria

    Hi, I am struggling with this strange problem. I have to find pairs of positive integers that satisfy two specific conditions. 1. you can’t go from one pair to another by subtracting/adding the same number to both members of the pair. 2. You can’t go from one pair to another by...
  29. J

    Equation measuring heat with temperature change, time and specific heat

    hello, If I had a substance (k) and heated it from Temperature1 to Temperature2, for z seconds, is there any (simple) equation that would give me the temperature (x) of this substance at the end? (knowing, of course, the substance's specific heat(C)) I found that: Q(energy exchanged during...
  30. B

    Finding Speed of a Mass in a Frictionless System at a Specific Time

    Homework Statement The three blocks shown are relased at t=0 from the position shown in the figure. Assume that there is no friction between the table and M2, and that the two pulleys are massless and frictionless. The masses are: M1 = 2.00 kg M2 = 7.00 kg M3 = 4.00 kg Calculate the speed of...
  31. L

    Specific heat and heat of fusion lab questions

    Homework Statement given the specific heat of water is 1.00 cal/(g*Celsius), what is the specific heat in Joules/(kg*Kelvin) Homework Equations I realize that this is simply a conversion factor issue but I have NO IDEA how to even start it.. The Attempt at a Solution I know the...
  32. P

    LED specific voltage for specific wavelength

    Hello I am trying to design a precise circuit for LEDs. I have a datasheet from a manufacturer and it says an LED is capable of running 3.0v at 640nm and 3.4v at 660nm. Is there a way to tailor the power (voltage) so that the LED will run exactly or at least approximately at 3.0v or 3.4v...
  33. PolywellGuy

    Specific Question about PWR Fission Reactors

    One fission reaction, of a U-235 nucleouse produces 2.4 Neutrons. In a pressurized water reactor, those uranium fuel rods are clad and sitting in water, giving off these neutrons. They are fast. The water slows them down, but does not absorb them and this generates heat. The inside of that...
  34. Z

    Wave Function in specific range

    I obtained the following from a book. Question is: Periodic Sawtooth described by the following; f(x) = x/2∏ for 0<x<2∏ f(x+2∏) = f(x) for -∞<x<+∞ The solution is: If x = 0 y = 0 If x = 2∏ y = 2∏/2∏ = 1 If x = 4∏ y = f(2∏+2∏) = 2∏ = 1 Can anyone...
  35. A

    Finding specific heat of an object graphically

    Homework Statement Samples A and B are at different initial temperatures when they are placed in a thermally isolated container and allowed to come to thermal equilibrium. Figure a gives their temperatures T versus time t. Sample A has a mass of 5.2 kg; sample B has a mass of 1.6 kg. Figure...
  36. J

    Ideal gas specific heat coefficients

    Hello, I'm trying to find the coefficients for the ideal gas specific heat at constant pressure in the form: Cp = a + bT + cT^2 + dT^3 (kJ/kmol.K) I need to find these coefficients for Octane. I have found them online in a slightly different form.. Cp = a + bT + cT^2 + dT^3 + eT^4...
  37. E

    Calculus gradient at a specific time

    The path of a particle is given by r(t) = tsin(t) * i - tcos(t) * j where t≥0. The particle leaves the origin at t = 0 and then spirals outwards. Let θ be the acute angle at which the path of the particle crosses the x-axis. Find tan(θ) when t = 3pi/2. I was able to figure out a...
  38. B

    How Do You Solve for 'a' in the Equation s = v0t + .5at^2?

    1. s = v0t + .5at^2 , solve for a 2. I don't know any 3. I don't know where to begin. I was thinking that you divide .5 from a to make it s/.5 = v0(t) + at^2.
  39. T

    Specific technical definitions of quantum terms

    I feel that a lot of the misunderstaing in quantum physics arises from the misinterpretations of terms used by physicists. I think that the forum should have a page where all the quantum terms are explained in a precise technical manner to avoid confusion. I will state pop culture's...
  40. G

    Holding a vector value for specific time

    I have been wracking my brain trying to figure this out. I have a 1xn vector I have gained through signal processing. I am multiplying it to another 1xn vector with a different scale. the first vector Xb moves to the next value every 1/1.023e6 seconds the second vector Xc moves to the...
  41. S

    How Do You Solve a PDE Model Similar to the Heat Equation?

    Hello, I derived a model in the form \begin{array}{rcl}\frac{\partial U(\vec{x},t)}{\partial t}&=&\gamma^2\Vert\nabla U(\vec{x},t)\Vert,\\\int_{\Omega}U(\vec{x},t)\, d \Omega&=&U_0,\quad\forall t\\U(\vec{x},0)&=&f(\vec{x}).\end{array} I don't know to solve that. THanks for help.
  42. F

    Proving that a subspace must have a specific number of elements

    Homework Statement Let V = (F2)^3, the set of triples (x; y ; z) of numbers in F2, the fi eld with two elements. V is a vector space over F2. Prove that any subspace of V must have either 1, 2, 4, or 8 elements. Homework Equations F2 = {0,1} The Attempt at a Solution The only...
  43. B

    Calculate Specific Heat Capacity HELP

    Calculate Specific Heat Capacity HELP! Hi guys, I having big troubles with how to calculate the specific heat (cp) for refrigerant r134a i gas phase. I think that assuming ideal gas behavior is a bad idea since this is going to be used in a actual system... I have values of entropy...
  44. N

    Derivation of the Debye Specific Heat Capacity

    Homework Statement Hello everyone! I'm using the text: "Elements of Solid State Physics - JP Srivastava (2006)" I have followed the argument leading up to the derivation of the Debye formula for specific heat capacity, so we now have; C_V = \frac{9N}{\omega_D^3} \frac{\partial}{\partial T}...
  45. A

    Specific heat capacity and temperature

    Why does the specific heat capacity of an object changes with temperature?Please explain in detail.Thanks..
  46. M

    Solving a Student's Experiment on an Ideal Gas: Molar Specific Heat Capacity

    Homework Statement A student performs an experiment on an ideal gas by adding 42.0 J of heat to it. As a result the student finds that the volume of the gas changes from 50 cm3 to 150 cm3 while the pressure remains constant at 101.3 kPa. i) If the quantity of the gas present is 0.007...
  47. S

    Specific Heat (kCal and J) for copper, help please

    Homework Statement How much heat is required to raise the temperature of a 50 gram cube of copper from 20 degrees Celsius to 45 degrees Celsius? (in kcal and J) Specific Heat(20degrees Celsius) for Copper (kcal/kg x degrees Celsius) is 0.092. and the Specific Heat for Copper (J/kg x degrees...
  48. J

    Thermodynamics specific volume, heat, & ideal gases

    Homework Statement I attached the problems. The first one is D) at the top of the page parts a) and b). The second one is E) at the top of the second attachment. 1) The rigid tanks shown below have volumes of .4m^3 and .004^3 respectively and each contains a water liquid-vapor mixture of...
  49. C

    What specific New Technology is the most useful to you personally?

    IT has seen a total transformation in the past decade. Which are the technologies you think is the most sought-after in the present trend?
  50. M

    Open Channel Flow: Specific Energy

    A trapezoidal channel with bottom width b = 30ft, side slopes m = 2, and flow Q = 5100cfs given, and I am supposed to plot a specific energy curve (E vs y). That part I have done. For the second part, it is given that 3 bridge piers, each 2 ft wide, are spanning the channel. With the same m...
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