Method for demonstrating the inverse square law and apparatus therefor

A variable torque pulley for demonstrating the inverse square law, comprising:

• a spiral member having a first central axis and a first perimeter, a first line-receiving groove disposed around said first perimeter;
• said first perimeter defined by an equation Dα1/θ2, where D is a distance from any point on said first perimeter to said first central axis, and θ2 is the square of an angle θ formed by (1) a line between said point D and said central axis, and (2) a reference line;
• a circular member having a second central axis and a second perimeter, a second line-receiving groove disposed around said second perimeter;
• said spiral member connected to said circular member so that said first central axis is coincident with said second central axis;
• and,
• a counter weight connected to said circular member, so that a center of gravity of said variable torque pulley aligns with said first and second central axes.

A system for demonstrating the inverse square law, comprising:

• a variable torque pulley for demonstrating the inverse square law, including:
• a spiral member having a first central axis and a first perimeter, a first line-receiving groove disposed around said first perimeter, and a distal end;
• said first perimeter defined by an equation Dα1/θ2, where D is a distance from any point on said first perimeter to said first central axis, and θ2 is the square of an angle θ formed by (1) a line between said point D and said central axis, and (2) a reference line;
• a circular member having a second central axis and a second perimeter, a second line-receiving groove disposed around said second perimeter;
• said spiral member connected to said circular member so that said first central axis is coincident with said second central axis;
• a counter weight connected to said circular member, so that a center of gravity of said variable torque pulley aligns with said first and second central axes.
• an axle disposed along said first and second central axes so that said variable torque pulley may rotate around said axle;
• a weight;
• a first line having a first end and a second end;
• said first end of said first line connected to said distal end of said spiral member;
• said second end of said first line connected to said weight;
• a force measuring device having a first end and an opposite second end;
• a second line having a first end and a second end;
• said first end of said second line connected to said second perimeter of said circular member;
• said second end of said second line connected to said first end of said force measuring device;
• and,
• so that said second line may be placed in said second line-receiving groove and wrapped around said second perimeter of said circular member and said second end of said force measuring device pulled, thereby causing said variable torque pulley to rotate about said axle, and causing said first line to be received by said first line-receiving groove and wrap around said first perimeter of said spiral member and thereby lift said weight, and causing said force measuring device to measure a force.