# Recent content by tmiddlet

1. ### Oxidation of iron

That's what I thought, but it is much easier to oxidize iron than either water or hydroxide according to the values I found... Why do I not get any iron hydroxide?
2. ### Oxidation of iron

I've got a question that is bugging me If I have a concentrated sodium hydroxide solution and electrolyze it with iron electrodes, some of the possible reactions at the positive electrode are 2H2O -> O2 + 4H++4e-. Eo = -1.23 V 4OH- -> O2 + 2H2O + 4e-. Eo = -0.40 V Fe -> Fe2+ + 2e-. Eo = 0.44...
3. ### Angular momentum at a distance

Thanks. That was the same as mine but much neater.
4. ### Angular momentum at a distance

Never mind, I managed to prove it. Thanks!
5. ### Angular momentum at a distance

Thanks a ton! This is exactly what I was looking for. Do you know of a proof of this?
6. ### Angular momentum at a distance

Say I have a situation like the image. I have a potentially complex object with moment of inertia I about its center of mass, mass M, velocity v and position r with respect to P. It is rotating with angular velocity ω about its center of mass What is the angular momentum about point P? I...
7. ### Size of planet with 1/50 gravity of earth

The universal law of gravitation is: F_g = \frac{mMG}{r^2} Where G = 6.674*10^{-11} \frac{m^3}{kg*s^2} The average mass density of the earth is 5.515 g/cm^3 (According to Wikipedia), so the acceleration due to gravity based on a planet with Earth's density and radius r is a =...
8. ### Average velocity question

You got speed right, speed is distance over time. Velocity is actually displacement over time.
9. ### RLC circuit voltages

You need to use Faraday's law to properly understand inductors. What is often misunderstood about inductors is that there is no voltage drop across an ideal inductor, it imposes an EMF in the opposite direction. Kirchhoff's law does not hold for inductors. What does hold is: \oint_C...
10. ### Impact Physics

You could approximate what would happen to an accurate degree. You would need to know the mass distribution of the horseshoe and the friction coefficients between the shoe and the stake, but a computer simulation would be possible.
11. ### Spring causing a mass to jump

Ok, I see. Easy mistake: x = \frac{4mg}{k} It seems everything else I did was unnecessary, I don't need to deal with the potential energy. So evaluating the integral: \int_{\frac{-4mg}{k}}^{d} (-kx - mg) dx = 0 Yields: d =\frac{2mg}{k} M \lt 2m This makes sense, Thanks!
12. ### Antenna length

I have been looking into how antennas work, and I have found that antennas of half wave-length are apparently optimal, but I don't understand why. If anybody could explain why this is, I would appreciate it. Thanks! (I do have an understanding of electromagnetic waves)
13. ### Spring causing a mass to jump

This is not a homework/coursework problem, but I came across it and wanted to check my answer. Homework Statement As in the diagram, there are two blocks of mass M and m. The mass m is suspended above M by a spring of spring constant k. Initially, the block m is pushed down with a force...
14. ### Can someone go over my work for this derivative?

That looks good to me.
15. ### Faraday's Law Lecture Error?

You're right: The closed loop integral of E dot dl is minus the change in magnetic flux through the open surface attached to the loop.