Click on a number to view the explanation of the corresponding item.

1. Rewind .

Resets the simulation to the previously chosen starting point.



2. Set the Ball's Initial Position.

To place the ball at an initial position other than the origin, click the Initial Position button. Then click at the point where you want the ball to be, drag the point if you like, and release the mouse button. The ball's initial position is now fixed. You can repeat the process to set the ball somewhere else.

While the mouse button is still held down, the coordinates of the point are displayed next to the point. To see what the ball's coordinates are after that, click the Data button (5).



3. Coordinate Grid .

Displays a coordinate grid, which may help you in judging positions.



4. Position Vectors .

Displays the initial and final position vectors. The initial position vector is shown dimmed.

When the Position button is selected, selecting the Data button (5) in addition will display the x, y components of the initial and final position vectors and of the displacement and average velocity vectors.



5. Data .

Toggle button that displays or hides two Data boxes titled 'average speed' and 'average velocity'. The boxes can be dragged independently by the green bar and can be closed independently by clicking the 'X' in the top right corner of either box.

Under 'average speed':

• s: distance traveled
• t: time elapsed since the beginning of the ball's displacement
• v_av: average speed

and under 'average velocity':

• displacement (magnitude and direction, the latter measured by the angle between the displacement and the positive x-axis taken between 0 and 360⁰
• average velocity (magnitude and direction, the latter measured as for the displacement)

When the Position button (4) is selected in addition to the Data button, the average-velocity box also displays the following data:

• the (x,y) components of the initial and final position vectors,
• the (x,y) componnents of the displacement vector,
• the (x,y) components of the average velocity vector.



6. Reset .

Resets the applet to its default setting.



7. Path and Displacement.

After the ball's position has been set, you can move the ball by clicking on it and dragging. The ball's displacement vector from the ball's initial to its final position is displayed in green. The actual path traveled by the ball is shown in blue.

The two Data boxes (5) display the time t elapsed while dragging the ball, i.e., while pressing down the mouse button, the magnitude and direction of the displacement vector and the distance s traveled by the ball along its path, plus other data.

Holding down the SHIFT key while dragging the ball results in a straight line path that is either horizontal, vertical, or at a 45⁰ angle.

After moving the ball along a path segment, you can move it along another adjoining segment by clicking on the ball again and dragging the ball. The time elapsed during the new drag will be added to the former total time elapsed.