Saturday, September 22, 2007
Mass Defect and Binding Energy
If you were given a problem like this: "How much energy is needed to separate two neutrons and two protons from C-12 considering that its actual atomic mass is 12.000", how can you solve it?
1. First the constants are:
1.007825 u - mass of a single proton
1.008665 u - mass of neutrons
2. Determine the atomic number of the element. The atomic number of the element determines the number of protons. In this case, C-12 has an atomic number of 6, thus the protons are 6 and the neutrons are six. (12-6=6).
3. Multiply the number of protons to the constant. (6x1.007825 u). Multiply the number of neutrons to the constant. (6x1.008665 u).
4. Add the two products to get the total mass and subtract it from the actual mass. [12-(6.04695 u+ 6.05199u)=12 u - 12.09894 u= 0.09894u].
5. The difference is the mass defect.
6. The binding energy is the energy needed to separate a particle from the nucleus.
BE= mass defect x 931.5 Mev/u where 931.5 is a constant. (Be= 0.09894u x 931.5MeV/u= 92.16261MeV)
7. The problem wants to separate 4 particles from the nucleus so 92.16 MeV/12=7.68 MeV. Then, 7.68 MeV x 4= 30.72 MeV.
The answer is 30.72 MeV.
Easy, right?
I wanted to learn at 10:17 PM.
Thursday, September 20, 2007
Balancing Equation
The first lesson we discussed this quarter is balancing an equation.
Example:
1. Rubidium-77 decays into Strontium-77.
The equation is:
7737Rb-->7738+?
7737Rb-->7738+01e
2. Radium-226 decays by Alpha emission. (a is Helium-4)
22688Ra-->42He+?
The equation is:
22637Ra-->42He+22286Rn
3. The equation is
147N+42He-->178O+?
147N+42He-->178O+11H
&&In xAy,
|*|A is the element
|*|y is the number of protons
|*|x is the number of nucleons (protons+neutrons; atomic weight)
&&In Alpha Decay, it is 42He
&&In Beta Decay, it is 0-1e
&&In Positron (positive electron) Emission, it is 01e
&&In Neutron, it is 01e
Balancing equations is much easier when you don't use you scientific calculator. Simple arithmetic is applied and just with the help of the Periodoc Table of Elements.
I wanted to learn at 10:38 PM.
Friday, September 14, 2007
First Post in the Second Quarter
I was been long since I haven't post here in my Physics Blog. It's been a while since I have not shared to you about the life of a typical third year student having big problems in his waterloo- Physics. I am not good in formula transformation nor in reasoning and in logic. I am dumb, but I'm a person trying to make things right. Mr. Mendoza gave me an 83 in my report card and surely, I the grade reflected me.
Second grading may be the time to change. Many requirements were implemented for us to change. One of these was a quiz notebook and another is the lecture notebook. These should serve as motivations for me to achieve more and do all the best that I can. Sadly, we were not required anymore to update this blog and post our feelings on it. But I am going to push through my posts not to have additional points but rather give Mr. Mendoza some ideas more about me.
The scope of our second grading, as far as I know, was all about nuclear physics. The first task Mr. Mendoza gave us is the readings about radiation. In the following day, we were asked to discuss one of the subtopics. After that, we were given a crossword type of quiz. I was easy, and for the first time, I got a perfect mark on my paper. This time, it was not a perfect zero, but rather a perfect 25.
I wanted to learn at 8:49 PM.