Recent content by beth314159

Let's examine three cases: 1: You jump off the block right after you both leave the plane. The block gets a kick down, you get a kick up, and hover slightly, then fall under gravity. You fall all the way to the ground, and splat. 2: You jump off the block right before you and the block...

ShawnD's response that "physics is just cancelling units'" is like saying that writing a book is "just typing on a keyboard". Sure, when you perform a calculation to solve a physics problem, you may cancel units. But physics is not about plugging through problems in a book. Granted, one's...

Graphical Solution There is an x (in your domain) where these two functions intersect. Graph them and see. (This is a trancendental equation, by the way.) -Beth

Ill posed Among other things, the problem as stated does not provide enough information to establish the velocity of the croquet ball. We are told the force (acceleration) impressed, but not the duration of the force (.8 s is the delay between the strike and the future collision with the pool...

Diffraction The relevant quantity is the ratio of the wavelength to the size of the hole in the barrier. A very short wavelength wave will not "notice" that it is going through anything other an infinitly wide opening, except near the edges. When the wavelength is comparable to, or larger...

It isn't only the speed that matters When trying to determine if you are going to be successful in pulling the cloth from under the cup, it is both how large the acceleration of the cloth, and the final speed reached by the cloth. If you gradually increased the speed of the cloth, the cup...

An odd word problem... Neglecting friction, etc., the cart and can are traveling together with a speed 6.26 m/s at the bottom of the hill. Now, if the cart stops dead, and the can slides off the cart, then, neglecting friction, or any sort of collision with the cart on the way off, the can is...

Definition of Plasma Loosely, and from Jackson's "Classical Electrodynamics," An ionized gas should be called a plasma when the length scale which separates short range and long range behavior is short compared to the length scale of interest. Not all ionized gases are plasmas. For...

Elements vs. atoms You are basically right. The word "element" was introduced, and even the periodic table constructed, before atomic theory was known. Now that we know that the reason that the substances we call elements (gold, helium, uranium), are special is that they are composed of...

Home Built Lasers -There are no laws regarding possession of lasers. -A diode laser is not the same as a light-emitting diode (LED), though they are related. -You could construct a low-power He-Ne laser fairly easily if you could fabricate and fill a discharge tube with He and Ne at the...

Start with the electron and proton infinitely far apart. Call this 0 potential energy. Now let them fall together under their electrostatic attraction. They feel an attractive force, and the energy of the final configuration is less than it was at infinity--i.e., work must be done to pull...

Ultracold plasma by ionization of ultracold atoms See this article: Phys. Rev. Lett. 83, 4776–4779 (1999) Creation of an Ultracold Neutral Plasma T. C. Killian, S. Kulin, S. D. Bergeson*, L. A. Orozco§, C. Orzel, and S. L. Rolston National Institute of Standards and Technology...