RC time constant problem — confusing problem statement

[Abo]

Homework Statement

It says that the Time Constant of an RC circuit is equal to 100 ms. What is the energy that remains in the circuit after 300 ms? "Nothing mentioned about whether it is in falling or rising edge".

Relevant Equations

The formulas that I have been using are :
W = 0,5 (C* V^2)
V = V0 ( e^-t/rc )

Hello!
It says that the Time Constant of an RC circuit is equal to 100 ms. What is the energy that remains in the circuit after 300 ms? "Nothing mentioned about whether it is in falling or rising edge".
The formulas that I have been using are :
W = 0,5 (C* V^2)
V = V0 ( e^-t/rc )
since I don't have the details about neither the initial voltage nor the capacitance I really don't know how to compute the energy? would it be a numerical value?

 

[berkeman]

Welcome to the PF.

If that's all the problem states, then I would take the word "remaining" to mean that the capacitor is being discharged by the resistor. And assume the initial energy stored is Eo based on an initial capacitor voltage of Vo. Then calculate the energy after 300ms as a fraction of Eo.

Give that a try and see how it goes...

 

[Abo]

Thank you for your reply. I did as you told me and I think it seems reasonable. Here is a photo of the solution.

 

[berkeman]

The photo is a little hard to read, but it looks good to me. Good work!