Velocity and position of electron

[tjbateh]

Homework Statement

An electron's position is given by R= 3t i + 4t^2 j + 2k, where t is in seconds and R is in meters. What are the (a) x-, (b) y- and (c) z-components of the electron's velocity? (d) What is the electron's speed? (e) What angle does the electron's velocity make with positive x-axis? Give all answers as appropriate functions of time.

Homework Equations

The Attempt at a Solution

So far, I have the
x-component = 3
y-component= 8t
z-component= 0

I have no idea how to find the speed, of the angle it makes. For the speed I put 3 + 8t, and it was wrong. I have one more try at the problem.

 

[Feldoh]

Speed is just the magnitude of the velocity (I.e. velocity without the direction part).

You have the components of the velocity vector how would you normally find the angle?

 

[tjbateh]

Ok so are you saying the speed is equal to 3^2 + 8^2...then take the square root of that??

And the angle is inverse tan of 8/3?