Recent content by kuruman

As @Steve4Physics noted the calculation that finds ##t = 0.14## s is incorrect because it assumes contant acceleration. The calculation that finds ##t=\frac{1}{4}T=0.11## s is correct because the time from relaxed length to maximum compression is indeed one-quarter period. Also note that things...

Sure but, to avoid confusion, I would have to ask all left-handed students to leave the room while doing that. I think the best bet is to make sure that every student's left hand knows exactly what their right hand is doing. :oldsmile:

I agree. However, too many times I have observed right-handed students during tests use their left hand to figure out the cross product and continue writing instead of putting their pen/pencil down. Prior warnings about this when I introduced the right hand rule went unheeded. Ahh, the dreaded...

There is another way of looking at this. First let's ask why the pilot loses consciousness. I would say that if he accelerates up with acceleration ##a## relative to the ground, the hydrostatic pressure between his heart and brain that is normally ##p=\rho g\Delta h## would now be ##p_a=\rho...

See alternative ways of finding the direction of the vector cross product here. :oldsmile:

My first thought was, have you considered using a smartphone physics app? Advantages 1. All high-school students have smartphones. 2. No equipment budget is needed. 3. Good excuse to bring smartphones to class in schools where they are banned. Disadvantage Using a smart phone a smartphone in...

Does it say anywhere "and you know what to do with the paper when you're done"?

IMHO 2.

Oops, I carelessly made it look that it is useless. The second equation should be $$E+m_{Li}c^2=2\sqrt{p_{\alpha}^2c^2+m_{\alpha}^2c^4}.$$ Sorry about that.

I don't think it is correct to write the momentum of the proton as ##mv## because that is not the relativistic expression. You are given that the total relativistic energy of the proton is ##E##. The momentum of the proton ##p## is what you get when you solve the expression...

As the problem states, v_c is the recoil velocity of the gun relative to the fixed Earth as required by momentum conservation in the horizontal direction. The problem is poorly phrased. I think you need to assume that the cannon is on a horizontal frictionless surface. This means that the...

I think that having (a) as the answer is based on the idea that the atomic orbitals in diamagnetic copper orient themselves to exclude (to some extent) the magnetic field lines. This is the physical mechanism behind diamagnetic levitation. Of course, the correct answer can be independently...

I will rephrase the question. Which of the four materials exhibits stronger diamagnetism? A superconducting sheet would work even better.

In addition to @Steve4Physics's comments: 1. Please note that we prefer that you post your work in ##\LaTeX## which makes the equations more legible and easier to refer to. To learn how, please click on the link "LaTeX Guide", lower left above "Attach files." To preview (and possibly edit)...

So why is the title of the book "Around the World in 80 Days"? :rolleyes: