What is the meaning of the rate of change of voltage in an RLC circuit at t=0+?

[paulmdrdo]

Homework Statement

Homework Equations

V(t) = V(∞)+( V(0+) - V(∞) )e^-t/τ

3. The Attempt at a Solution

Hello again! I've already solved the problem depicted in the picture above and below are the following unknowns that I managed to solved:

These results checked out with the answers supplied by the book. By I could not make sense out of these results. For example how come that at t=0+ the rate of change of the voltage across the 2-ohm resistor is dVr(0+)/dt = 2/3 v/s, when in fact the expression for the voltage across it is Vr(t)=4 V ----> this is a constant value how come it has a rate of change of some sort? Same confusion I have with the rate of change of voltage across the capacitor because Vc(t)=-20v.

Please enlighten me with this matter. Thank you!

 

[rude man]

What reasoning led you to conclude constant voltages for the 2 ohm and C? When the switch is closed for the 3A supply, everything starts to move - all voltages, all currents!