Questions Asked on
June 28, 2005

radio message
The nearest star beyond the sun is Alpha Centauri, 4.2 x 1016 meters away. If we received a radio message from the star today, how long ago would it have been sent? The distance that light travels in a vacuum in one year, approximately 9.46 trillion (9.46

algebra anyone
How to you compute the intercepts of a quadratic function? For the xintercept, set x to 0. For the yintercept(s) (if any), set y to 0.

physics
Hi, I am confused about physics, more specifically force. I know that the formula for force is: f=ma So what if an object traveling at constant speed (acc equals zero) collides with a wall? How would you calculate the force, since there is no acceleration?

Sodium Vapor
How might you distinguish a sodium vapor street lamp from a mercury vapor steet lamp? http://en.wikipedia.org/wiki/Sodium_lamp http://en.wikipedia.org/wiki/Mercuryvapor_lamp I think you would see colors better with the Mercury Vapor Light You can

radioactive decay
What elements results if one of the neutrons is in a nitrogen neucleus is converted by radioactive decay into a proton? The atomic number goes from 7 to 8, while the atomic weight stays the same. An electron (beta) is emitted from the nucleus. Actually,

algebra
: In case of a quadratic function, why are there two xintercepts and one yintercept? Let's say x^2 = y, which is a quadratic function. For every value of y, there are two possibilities for x. For example, if y is 4, x can either be 2 or 2.

electron
An electron drops from the fourth energy level, in an atom to the third level and then to the first level. Two frequencies of light are emitted. How does their combined energy compare with the energy of the single frequency that would be emitted if the

chemistry
Use the shell model to explain why a lithium atom Li, is larger than a beryllium atom, Be. I don't think it is larger. It has a lower atomic number 3 vs 4. It is therefore lighter see below link and click on elements. http://www.webelements.com/