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  1. R

    Calculate attractive force between Cu2+ and O2- ions.

    The equation F= ke(|q1q2|)/r2 looks good. So if I plug in 3.204 × 10^-19 coulombs for q1 and -3.204 × 10^-19 coulombs for q2 (because O2- has a net charge equal to -2 times the charge of an electron and Cu2+ has a net charge equal to twice the charge of an electron), then I get 2.307*10-8...
  2. R

    Calculate attractive force between Cu2+ and O2- ions.

    Well I don't know the force equation, my teacher only gave us the equation for bonding energy... Perhaps since energy=force*distance we can find force by dividing our energy equation by some distance? I'm still stuck but I see now that z_1= 2 and z_2=-2. Any more help?
  3. R

    Calculate attractive force between Cu2+ and O2- ions.

    Homework Statement Calculate the attractive force between a pair of Cu2+ and O2- ions in the ceramic CuO that has an interatomic separation of 200pm. Homework Equations E_A= -\frac{(z_1\cdot e)(z_2\cdot e)}{4\pi\cdot\epsilon_o\cdot r} Where z_1 and z_2 are the valences of the two ion...
  4. R

    Finding number of atoms per cm^3 of zinc?

    Homework Statement Zinc has a density of 7.17 Mg/m^3. Calculate (a) the number of Zn atoms per cm^3, (b) the mass of a single Zn atom and (c) the atomic volume of Zn. Homework Equations atomic mass of zinc = 65.39 g/mol The Attempt at a Solution For part (a) I use the fact that...
  5. R

    Finding the energy of an electron from n=4 to n=2?

    Homework Statement Find the energy of a He+ electron going form the n=4 state to the n=2 state. Homework Equations E_n=\frac{m\cdot e^4 \cdot z^2}{2n^2 \cdot \hbar^2} Where m= mass of electron, z= atomic number, e= charge of an electron, n is the energy level. ^ I think those are...
  6. R

    Computing energy in the electron of Li 2+?

    Homework Statement Using the Bohr model of the atom, compute the energy in eV of the one electron in Li2+. Homework Equations E_n=\frac{m\cdot e^4 \cdot z^2}{2n^2 \cdot \hbar^2} Where m= mass of electron, z= atomic number, e= charge of an electron, n is the energy level. ^ I think...
  7. R

    Period of an Oscillating Particle

    Sorry, how do we have ## \frac {dt} {dx} = f(x) ##?
  8. R

    Period of an Oscillating Particle

    "Period" is the time it takes for the particle to make one cycle. The particle traveling from 0 to A takes 1/4 of the time it would take to travel the whole period. But I don't see how we can find the time it takes the particle to travel from 0 to A? We have this equation that gives us time...
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    Period of an Oscillating Particle

    If ##\frac{dx}{dt}=a+x## then ##\frac{1}{a+x}dx=dt## (whatever that means), so ##\int \frac{1}{a+x} dx = \int dt = t##. So ##ln(a+x)=t##. If ##\frac{dx}{dt}=x^2## then ##\frac{1}{x^2}dx=dt## (once again idk what exactly i'm doing there), so ##\int \frac{1}{x^2}dx = \int dt##. So...
  10. R

    Period of an Oscillating Particle

    I'm afraid I don't get what it means to take ##\frac{dx}{dt}=f(x)## and turn it into ##\frac{1}{f(x)}dx=dt. And thus I don't get what it means to then take the integral of both sides of that... can you help me make sense of what those procedures mean?
  11. R

    Period of an Oscillating Particle

    oh whoops the integral of velocity is displacement so we would have x(t). So we could solve x(?)=A and then multiply it by 4 to get the period?
  12. R

    Period of an Oscillating Particle

    ##\frac{dx}{dt}=f(x)## ##\frac{1}{f(x)}dx=dt## ##\int f(x)^{-1} dx = \int 1 dt=t## is that right? That would give us time as a function of velocity which can give us velocity as a function of time? Then we can integrate that with respect to t to find displacement as a function of time...
  13. R

    Period of an Oscillating Particle

    Since the input into our velocity equation we found is x not t, I should edit: ... to say: See how as we make Δt smaller and smaller, the above becomes a better and better approximation of displacement x as a function of time? But I don't know how to turn that method into an integral...
  14. R

    Period of an Oscillating Particle

    Homework Statement A particle oscillates with amplitude A in a one-dimensional potential that is symmetric about x=0. Meaning U(x)=U(-x) First find velocity at displacement x in terms of U(A), U(x), and m. Then show that the period is given by ##4\sqrt{\frac{m}{2U(A)}}\int_0^A...
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