Charged particles and cylindrical coordinate system

[Ry122]

A charged particle in a magnetic field is spiralling along a path defined in cylindrical coordinates by r
= 1 m and θ = 2z rad (where z is in meters). The speed along the path is constant at 3.87 km/s. What is
the z-component of the velocity, vz, in cylindrical coordinates?

My attempt: I'm just needing someone to point me in the right direction as to what equations to use here, and how to make use of cylindrical coordinates.

 

[gabbagabbahey]

A charged particle in a magnetic field is spiralling along a path defined in cylindrical coordinates by r
= 1 m and θ = 2z rad (where z is in meters). The speed along the path is constant at 3.87 km/s. What is
the z-component of the velocity, vz, in cylindrical coordinates?

My attempt: I'm just needing someone to point me in the right direction as to what equations to use here, and how to make use of cylindrical coordinates.

What is the general expression for position in cylindrical coordinates? How about velocity?