The set up is a damped oscillator governed by a differential equation of the form mx'' + bx' +kx =0, where m,b,k are arbitrary constants (for the case of a mechanical oscillator then m=mass, b= the damping constant and k is the magnitude of the spring constant). You can move the sliders to change the constants and see how the displacement varies with time (the blue line) and how the velocity varies with time (the dashed line). Experiment with the constants by moving the sliders. Notice how if the damping is strong compared with the spring constant (b^2 > 4mk) we have overdamped motion, but if the damping is small (b^2 < 4mk), the motion becomes oscillatory. You can also change the initial conditions (the velocity and displacement when t=0) by sliding the relevant starting points up and down the y-axis.