The work-kinetic energy theorem can be applied to the motion of a charged particle in a uniform electric field to relate the particle's displacement to changes in the particle's kinetic energy or speed.
The applet on Page 6 will let you simulate the motion of a charged particle in the uniform electric field of an infinitely extended parallel-plate capacitor. Details on how to use the applet are available under Applet Help on the applet's Help menu.
When you experiment with the applet on Page 6, open the item "Activities Page 6" under Related Items for suggestions on investigations to be carried out with the applet.