# Search results

1. ### 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...
2. ### 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...
3. ### 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...
4. ### 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...
5. ### 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...
6. ### 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...
7. ### 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...
8. ### Equilibrium, Torque and Friction (hard)

Homework Statement A uniform solid cube, of edge 1m and weight 200N, rests on a rough horizontal plane. A light rod AB of length 1.2m is smoothly hinged at A to a point of the plane and B is in contact with a smooth face of the cube. The rod lies in a vertical plane perpendicular to...
9. ### A Series of Even numbers squared

Homework Statement Is there a general formula for the sum of such a series (or can it be self derived) ? 2^2 + 4^2 + 6^2 + 8^2 ..... N^2 (all the way till some even number N) Homework Equations \sum r^2 (from r=1 to r=N) = 1/6 * n(n+1)(2n+1) The Attempt at a...
10. ### Covalency and Oxidation Number in Covalent Compounds

Homework Statement NCl_{3} What is the Co-valency / Oxidation number of Nitrogen in this Covalent compound ? Homework Equations I think the table of electronegativity might be useful The Attempt at a Solution Nitrogen must be "-3" since it is more electronegative than Chlorine. The...
11. ### Permutations : hard question !

Homework Statement In how many ways can the three letters from the word " GREEN " be arranged in a row if atleast one of the letters is "E" Homework Equations Permutations Formula The Attempt at a Solution The total arrangements without restriction: 5P3/2! = \frac{5!}{2! * 2!} The number...
12. ### Combinations Question ; I must be missing something

Homework Statement A large Box of biscuits contains nine different varieties. In how many ways can four biscuits be chosen if : a)Two are the same and the others different b)Two each of two varieties are selected c)three are the same and the fourth is different Homework Equations...
13. ### Photoelectric effect and Compton scattering difference

What is the difference between the two ? Maybe that in the photoelectric effect all of the energy of a photon is absorbed by the electrons ? Is that it ? In Compton scattering, only part of the energy is absorbed hence there is a photon of lower frequency emitted ! OR Maybe in the...
14. ### Confusing Algebra based question

Homework Statement If ADD = 9 BAD = 7 CAD = 8 Find ADA . Homework Equations Algebra The Attempt at a Solution ADDBAD=9*7 BADCAD=56 ADABCC= 56*8/9 B/C = 7/8 I really don't know how to approach this problem, what must I eliminate and how should I do it ?
15. ### Basic Algebra based question

Homework Statement A man had a ten gallon keg of wine and a jug. One day, he drew off a jug full of wine and filled up the keg with water. Later on, when the wine and the water had got thoroughly mixed, he drew off another jugful and again filled up the keg with water. The keg then contained...
16. ### Electrode Potentials and Redox reactions

What is the relation between Electrode Potentials and Redox reactions ? Can we determine the relative strength of reduction of a metal by looking just at the electrode potentials ? Here is a particular thing that confuses me : We know that the standard electrode potential of Lithium is...
17. ### Question on Number theory

Homework Statement How many four-digit numbers formed of only odd digits are divisible by five? Homework Equations Permutations The Attempt at a Solution Here is what I think should be done : Ans : 4P3 * 1 = 24 Is that right ?
18. ### What exactly is centrifugal force

I think that there is no such thing as centrifugal force . Am I right ? is this force fictitious ?
19. ### The vector nature of Angular Momentum

Here is an animation from Wikipedia : http://en.wikipedia.org/wiki/File:Torque_animation.gif The angular momentum is given by the Cross product of r and p We can see that the direction would be perpendicular to the direction of rotation of the particle (as shown in the animation) I don't...
20. ### A rudementary question on dark matter

I think that there is mass associated with all dark matter in the universe and this mass is much greater than the total mass of the stars in a particular galaxy. Now, if I were to classify the mass into two categories : 1. visible 2. invisible How would I carry that out ? Is dark...
21. ### How does this clock work ?

Homework Statement see attachment Homework Equations θ= ω*τ The Attempt at a Solution Nothing. Instead I have some queries about the question itself : 1.Is this a proper clock, will it show the correct time as any normal clock ? 2.what is the angular displacement of one of the...
22. ### Natural Log : seems as a discontinous function

The function f is continuous at some point c of its domain if the limit of f(x) as x approaches c through the domain of f exists and is equal to f(c). In mathematical notation, this is written as lim_{x\rightarrow c} f(x) = f(c) from the positive and negative sides . For ln(x) (the natural log...
23. ### Nuclear Binding Energy (wikipedia is confusing)

http://en.wikipedia.org/wiki/Nuclear_binding_energy What is nuclear binding energy ? Here are two possible answers according to the Wikipedia page : 1.Nuclear binding energy is the energy required to split a nucleus of an atom into its component parts. 2.Nuclei are made up of protons and...
24. ### Capacitors: How do they store energy ?

A Capacitor stores energy when it is charging up but what is the intuition behind such a process ? I, in fact, think that as electrons are being stored on one of the plate, positive charge is being build up on the other plate, an electric field is set up as there is a separation of charges, and...
25. ### Exponential Conundrum

Homework Statement Positron Emission Tomography (PET) scanners frequently operate us- ing the radioactive isotope 18F, which has a half life of about two hours. The isotope is incorporated into a drug, half of which is excreted by the body every two hours. How long will it take before the...
26. ### Gravity in the upper atmosphere

Homework Statement See attachment Homework Equations Centripetal acceleration Mv^2/r The Attempt at a Solution I guess the answer to be D But I am not quite sure about the same rate of acceleration. If we hypothetically remove the space station and visualize the astronaut orbiting around...
27. ### Circuit analysis potential difference

Homework Statement What is the Potential difference between X and Y ? Homework Equations KVL and KCL The Attempt at a Solution I am confused about the two possible answers : 1. 9V (From general concepts) 2. 3V (after applying the KVL and KCL) I think the 2nd answer...
28. ### Application of Circuit laws (KCL and KVL)

Homework Statement Calculate the resistance of this combination of resistors Homework Equations V=IR The Attempt at a Solution By using KVL : V= 3I_{5} = I_{2} = 2I_{4} I = I_{1} + I_{2} I_{3} = I_{2} + I_{4} I_{1} = I_{5} + I_{4} I = I_{3} + I_{5} Now the final result could be...
29. ### What is the power of this bulb

Homework Statement See attachment The question asks to calculate the brightness of the bulbs(g and h) in this new configuration. Homework Equations Since brightness \propto Power P= V^{2}/R P= I^{2}R E.M.F of One cell : V The Attempt at a Solution I used the equation P...
30. ### What is the mass measured on another planet ?

Homework Statement See attachment Homework Equations W = mg The Attempt at a Solution I did this : W(on Mars) = 93*8.8 (since the measuring machine was calibrated on venus) Mass = 93*8.8/3.8 My answer is 215Kg. Can someone confirm its validity ?