Spherical pendulum confusion [Issue resolved]

[member 731016]

Homework Statement

Please see below.

Relevant Equations

$F_g = mg$

For this problem,

I am confused my what they mean by $\phi$. I have looked at the figure, but it is confusing. Makes it look like the x-axis and y-axis are not perpendicular, even thought I'm assuming they are since this is a right handed coordinate system. Does someone please know what $\phi$ is in the diagram?

I propose a better diagram:


Any help greatly appreciated - Thanks!

 

[TSny]

I am confused my what they mean by $\phi$. I have looked at the figure, but it is confusing. Makes it look like the x-axis and y-axis are not perpendicular, even thought I'm assuming they are since this is a right handed coordinate system. Does someone please know what $\phi$ is in the diagram?

Yes, the x and y axes are perpendicular.

Imagine the position of the bob projected vertically upward to a point P in the horizontal x-y plane. The line from the origin through P is shown dotted in the diagram. $\phi$ is the angle between this line and the x-axis. $\phi$ is the "azimuthal" angle around the z-axis.

 

[Frabjous]

This is just standard spherical coordinates with r = constant “l”.