Exploring Potential Energy Graphs

In this activity, students explore the graphical representation of potential energy in one dimension. Students also investigate the roles of kinetic energy (KE), potential energy (PE ) and total energy (Etot) in determining an object's motion. As seen below, the red curve represents the object's potential energy, the blue line represents the object's total energy and the object's current state is represented by the purple dot. The potential energy can be manipulated by dragging the red rectangular markers on the curve up and down. (The resulting potential energy curve is produced by using a spline curve to follow the rectangular markers.) The total energy can be manipulated by dragging the blue rectangular marker blue horizontal line up and down. The starting condition of the object can be altered by draging the purple circle to the left and right (along the PE curve). Changing the position of the object changes the object's Kinetic Energy (KE is shown in green) since it is the difference between the object's potential energy at its current location and the object's total energy.

Below the Energy graph the a graph of the resulting force is displayed. At the bottom of the window the object's position are motion are shown, with a vector to indicate the force on the object. To the right of the energy, force and motion graphs is a combined bar chart showing the object's instantaneous potential, kinetic and total energy. A snapshot of the complete applet window is shown below.

At the bottom left of the window are the player controls. The play/pause button starts the motion simulation of the object based upon the potential energy graph and the position of the object. When the simulation is restarted, the object's motion is always taken as being towards the right, regardless of any previous runs of the simulation. The motion cannot be started if the kinetic energy is negative (since this is unphysical) and the objects properties cannot be manipulated while the simulation is playing. The step button allows the operator to step through the simulation. The reset button sets the potential energy, the total energy and the object location all back to their defaults (as seen when this applet first starts up).