Help with energy conservation calculations

Attention physicists, I need help.

First year university physics student here, and I need assistance finding the kinetic energy of an object (specifically, a mousetrap car our lab team built).
I already found the speed, acceleration, net force, and work, we were given the Ek of the mousetrap spring (100N/cm = 1J), I already know the equation to find Ek (1/2 mv^2), and I know energy is conserved, not created, not destroyed, etc.
The question is, using the values I have, how do I complete the energy conservation calculations?

I can provide data from the trials if needed.

In before "lol failure", it's only a bullshit degree breadth course I'm required to take.

the kinetic energy decreases in time as the car is slowing down...

1/2*k*x^2 = 1/2*m*v(t)^2-int(F*dx,x=0..A)
Assuming the spring delivers 100% of it's energy, the energy of the spring is the total energy the car will revieve, this is equal to the speed at time t minus the frictional force * the distance traversed. Do you want me to do the math on the right hand side??