## Exploration 5.2: Force an Object Around a Circle

In this Exploration you are looking down at a black ball on a table top. Drag the crosshair cursor (position is given in meters and time is given in seconds) to within 5 m of the 0.2-kg ball. The cursor will then exert a constant force on the black ball. You may choose either an attractive or a repulsive force. In addition, the black ball is constrained to move in a circle by a very long wire. The blue arrow represents the net force acting on the mass, while the bar graph displays its speed in meters/second. Restart.

For both attraction and repulsion, drag the cursor around to see how the net force varies.

1. At the beginning of the animation (before you move the cursor), in what direction does the net force point?
2. With this force, does the ball move?
3. What type of applied force makes the ball acquire a tangential velocity?
4. Describe the direction of the force that makes the ball acquire the maximum tangential velocity for the force applied.
5. When the ball has a tangential velocity, in which direction does the net force point when the cursor is nearby? In what direction does the acceleration point?
6. With the object moving, drag the cursor far away from the ball. In what direction is the net force now? What is the direction of the acceleration? Why? Physlets were developed at Davidson College and converted from Java to JavaScript using the SwingJS system developed at St. Olaf College.

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