# Questions Asked onJune 28, 2005

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

2. ## 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/Mercury-vapor_lamp I think you would see colors better with the Mercury Vapor Light You can

3. ## 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?

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,

5. ## 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

6. ## algebra anyone

How to you compute the intercepts of a quadratic function? For the x-intercept, set x to 0. For the y-intercept(s) (if any), set y to 0.