# Homework Help: Potential energy of quarks

1. Feb 20, 2006

### UrbanXrisis

I am to find the ratio of the gravitational PE to the Coulomb PE between a $$t$$ and a $$\bar{t}$$ quark

I dont know what a $$\bar{t}$$ quark is, but I am guessing that it is a quark that has a charge opposite of that of the $$t$$ quark?

I am given that the charges are $$+/- \frac{2}{3} e$$ and that the mass is 174 GeV/c^2.

I think this is how I should set this question up:

$$ratio=-\frac{GMm}{kQq}$$

$$ratio=-\frac{2G (174 GeV/c^2)}{k(\frac{2}{3} e) (-\frac{2}{3} e)}$$

is this correct?

Last edited: Feb 20, 2006
2. Feb 20, 2006

### phucnv87

The ratio should not be negative. The rest of the solution, I think that you're right.

Last edited: Feb 21, 2006
3. Feb 20, 2006

### UrbanXrisis

why should the ratio not be negative? and what is a $$\bar{t}$$ quark?

4. Feb 20, 2006

### Physics Monkey

Usually the bar means its the antiparticle. In this case you have the top quark $$t$$ and the anti-top quark $$\bar{t}$$. The ratio of the two energies should be positive because both energies are negative.

Also, the gravitational potential energy is proportional to the product of the masses so you should have the mass squared rather than multiplied by two.

Last edited: Feb 20, 2006
5. Feb 20, 2006

### UrbanXrisis

oh right, so something like..

$$ratio=\frac{G (174 GeV/c^2)^2}{k(\frac{2}{3} e)^2}$$