Push me, Pull you

The window at left displays an undriven frictionless spring system consisting of two masses connected by one spring. The spring force is the only force on the springs. The scale on the right edge of this graph shows the position of mass 1 and that on the left edge shows the position of mass 2. When both masses are positioned at their respective \(0\) points, the spring is relaxed. Mouse-clicking and dragging either mass resets the initial condition.

You can click on the scales to cause the mass to jump to that value. This resets the initial conditions to their current values and resets the time to 0.

Check boxes toggle display of the position and velocity of the two masses in the graphing window at upper right. To the right of these checkboxes is a readout of the values for the selected value of \(t\). If a velocity display is selected, a diamond appears to one side of the corresponding mass; dragging it specifies an initial velocity.

There is also a checkbox which toggles display of the center of mass in both the graphing window and the spring window.

Clicking the [>>] key animates this system and causes graphs of the positions and velocities of the two masses to be drawn as selected. When the animation begins the key is replaced by [||]; selecting it halts the animation. When \(t\) reaches its maximum value the key is replaced by [<<]; selecting it returns \(t\) to \(0\);

Rolling over the graphing window creates crosshairs and a readout of \(t\) and \(x\). Depressing the mousekey suppresses the crosshairs.

Selecting [Show all \(t\)] at lower left will display the full time series for position and velocity as selected.