Recent content by jdog

This notion that there are somehow equal numbers of these particles in existence is not correct. Protons and electrons are constantly being created and annihilated throughout the universe in unrelated processes, and due to the relativity of simultaneity, you can't count them at anyone instant.

The gravitational field also has to travel at the speed of light. The gravity you feel now from the sun is pulling you towards where it was 8 minutes ago.

I think the short answer is, no. You will need to do an integral. Find a friend who has taken calc 2.

Hi Highly recommend the cartoon guide to physics. It helped me through general physics I and II, and now I make my students buy it. It will give you a real qualitative understanding of all that stuff.

Yeah, Nasu is right too, but that L shouldn't really affect anything qualitatively.

I may not understand the simulation, but I do have something that may be of interest. The expression you have, "acclereration = -(g/L)*theta" is an approximation. The true differential equation should have a sin(theta) rather than theta. The approximation only holds for small angles. Could this...

Can you be more specific? What do you mean by, "behave so well in accordance"?

If you are going to take e to be a positive number, then the charge of the electron has to be -e. You have a positive number of particles. Good that you recognized that your answer didn't make sense.

How about this, a loop of wire absolutely hates having its magnetic flux changed. It will do everything it can to try to keep it the same, i.e. induce a current, and thus a magnetic field to replace the old one, or counter the new one. Lenz's law tells you which way to point your thumb to figure...

Yes. The Strong force goes like exp(-ar)/r so it falls off very quickly when r is large, and the columb force (with it's 1/r^2 dependence) dominates when r goes to zero, So the strong force will only hold protons in place if they are close enough, and if they get too close, the columb repulsion...

I disagree with everyone. First, this is a perfectly valid question, and I think, a profound one. Second, the simple answer is no, there will exist a reference frame where these events happen in reverse order. This is because the two events, the sending of the signal and the awarding of the...

I would say not unless it's going down hill. However, if you're in the vehicle, you are most likely going to come to a stop and watch that wheel roll ahead of you.

yes, I'm afraid you are. What you have calculated is it's average velocity, the total displacement divided by the total time. To find the velocity at take off, you first have to find what that constant acceleration is, then see how fast it's going after 8 seconds of accelerating at that rate...

At the very least, it shouldn't really be too hard to concieve of the units of acceleration. Meters per second per second means how many (meters per second) it gains every second.

If it were me, I would start with the mass and spring model. Let the velocity decrease linearly to zero then increase back to where it was, but in the other direction. Keep the slope the same no matter how fast the ball approaches the wall. This will create the parabolic motion that a bouncing...