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  1. H

    Finding the number of arrangements

    Which problem are u addressing : 1. 3 Reds and 3 Blues 2. 6 red and 3 blues If the FIRST one then here is my question to u : How can two red balls touch each other for it is given that the blue balls must be apart from each other . If any red ball was to touch another red ball, the two of...
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    Finding the number of arrangements

    *amazed* You are right. So how would we proceed in this case , do u have any leads ?
  3. H

    Finding the number of arrangements

    Lets put our method to test, what if the number of red balls and blue balls were not equal . There are 5 red balls (distinguishable) and 3 blue balls (distinguishable) , find the number of possible permutations in which all blue balls are not next to each other . I would speculate : for the...
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    Finding the number of arrangements

    Homework Statement In how many ways can 3 red and 3 blue balls be arranged if no two balls of the same colour are next to each other ? Homework Equations .... The Attempt at a Solution Here is what i did (Which is wrong) 6 x 3 x 2 x 2 x 1 x 1 I did this since there are 6...
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    Electrolysis of Iron(II)Sulphate

    It does indeed but that is something different. In this particular example we have : Fe(II) ions , water molecules, extremely low number of Hydrogen ions and hydroxide ions, Sulphate ions . Since the concentration of Hydrogen ions is almost negligible (as is the case in any aqueous...
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    Electrolysis of Iron(II)Sulphate

    Homework Statement I am given a 1 M solution of Iron(II)sulphate(aq) and it is being electrolyzed using inert electrodes . What will form on the cathode ? Homework Equations Reduction potentials of : Fe =-0.44V of water to from hydrogen : -0.83V The Attempt at a Solution Since...
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    Moment of Inertia - Swinging arms

    No, it is τ = Iα where α is the angular acceleration
  8. H

    Simple Harmonic motion : Is energy conserved

    It is a needle which is being moved by an automated sewing machine I really can't see why do you need that information to answer the question : Why isn't Energy conserved in this problem ? In ANY case, the total energy at each and every point (displacement) during the SHM must be the same
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    Simple Harmonic motion : Is energy conserved

    I thought i had uploaded it, sorry for that. Anyways, it is under gravity and it is going SHM. (why wouldn't it)
  10. H

    Simple Harmonic motion : Is energy conserved

    Homework Statement I doubt energy is conserved in SHM, or it might be possible that i be doing something wrong. The particle (red dot) in the attachment is at its equilibrium position and oscillates with Simple Harmonic Motion between the two yellow colored plates. Amplitude A = 1.5 m...
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    The concept of rotational equilibrium

    I cant see the logic in your answer . I think that even if all three forces were passing through the Center of mass, there MIGHT still be a net torque ! Let me prove it : https://www.physicsforums.com/attachment.php?attachmentid=57701 Consider this diagram in which the three forces are...
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    The concept of rotational equilibrium

    This book was recommended as a great book for introductory physics by ppl here on PF Physics for Scientists & Engineers by Serway. As mentioned in the first post, there was this quiz on page 349~350 which asked whether the given object is in equilibrium, i stumbled across it while reading...
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    The concept of rotational equilibrium

    Here is a text from my Physics Book : The net external torque on the object about any axis must be zero for it to be in rotational equilibrium. I divide the torques into two categories, anticlockwise and clockwise. (This approach works fine for 2-D objects but will it work for 3-D objects...
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    Kinetic Energy Formula definition explanation

    Work done on an object and one of the equation of motion for constant acceleration : V^2 - U^2 = 2AD (A= acceleration vector)(D= Displacement vector)(the rest is self explanatory) W=F.D
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    Approximating a Simple Harmonic motion

    Understandable, my presentation is confusing, that is why you misunderstood my approach. The variable "r" has a value of "a" in this situation. (both of them are just lengths and have dimensions of length) Thanks for the explaining about the mathematical model for the signs . At least now...
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    Approximating a Simple Harmonic motion

    No there is no typing error, i just rechecked the solution archive, it is exactly as i wrote it ! I really can't say anything about its direction since i have not defined them yet. Lets do that ! For the tension Let the clockwise tangent be -ve and the tangent which points in the anti...
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    Approximating a Simple Harmonic motion

    Homework Statement Homework Equations F=ma The Attempt at a Solution I did the first three parts . The last part of this question is quite hard, i tried using newton's 2nd law of motion but ... here is what happens : T is the tension, as stated in the question . so the equation of...
  18. H

    The positioning of the thermometer

    I find that plausible, but would you care to share some experimental results to back this hypothesis ? If i understand your claim correctly: (correct me if i misunderstood) The temperature at the surface is the true boiling temperature of a solution while that deep inside the liquid is...
  19. H

    The positioning of the thermometer

    Simple, since the air just above the surface will be most saturated with the vapors (water) which would exert a pressure along with the atmospheric pressure. Thus the total pressure would just be the sum of the two pressures . (first by vapors and the second by atmosphere). Let me convince...
  20. H

    The positioning of the thermometer

    While the solution is boiling, the pressure at the surface of the liquid will be greater than the atmospheric pressure (14.7 PSI). The pressure at the bottom of the surface will be the sum of the pressure due to the hieight of the liquid and the vapour pressure above the liquid. Will that...
  21. H

    The positioning of the thermometer

    A thermometer doesn't "measure" pressure so i am guessing the key point over here might be that the thermometer ( which is in fact a glass thermometer) might break ? But if that were true, why the need for partial immersion ?
  22. H

    The positioning of the thermometer

    Hello, I am instructed by my chemistry professor to design an experiment to measure the temperature at which a saturated solution of Sodium Nitrate will begin to boil. If the reagents are pure this temperature will be constant . Can someone tell me why does the lab instructor suggests...
  23. H

    Finding the moment of inertia

    Homework Statement Two uniform square laminas are combined into a single body. One lamina ABCD has mass 5m and the other lamina PQRS has mass m. The lamina PQRS has side 2a, and its vertices are at the mid-points of the sides of ABCD, with P on AB and S on AD. The line PS meets AC at K, and...
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    Equilibrium, Torque and Friction (hard)

    Ah, i see, i misunderstood the question (yet again) . CB = 1.2sin(30) = 0.6
  25. H

    Equilibrium, Torque and Friction (hard)

    I am not quite sure what u mean by that statement. Aren't these the distances from the line of action of the force (extrapolated) and the pivot : Shown in Green colour in the diagram .
  26. H

    Equilibrium, Torque and Friction (hard)

    That's simple : The perpendicular distance from the line of action of the forces to the Pivot D (i am taking moments about D)
  27. H

    Equilibrium, Torque and Friction (hard)

    I still can't seem to solve this question : Here is what i did but failed : Taking moments about D : since the reaction force acts through D thus it produces no moment about D. Weight produced an anti clockwise moment about D and Normal force at (which i need to find out) , F produced a...
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