Homework Help: Does Linear momentum operator and angular momentum operator

1. Feb 10, 2010

hellomister

1. The problem statement, all variables and given/known data
Does Px Lx operators commute?

2. Relevant equations
This is just me wondering

3. The attempt at a solution
I tried doing this and I got something weird, my friend said that when you take a derviative with respect z or something that when you try to take the derivative of something that's not with respect to z it goes to 0. Is this true? p.s. im not very good at math.

2. Feb 10, 2010

chrispb

You tell me. L_x is made up of rs and ps. Which r and ps is L_x made of, and which r and ps does p_x commute with?

3. Feb 10, 2010

SkeZa

$$\hat{\vec{L}} = \vec{r} \times \hat{\vec{p}}$$

$$\times$$ is the cross product...

Do the math and then see if they commute

ps
[px , py] = [px , pz] = 0