Swinging bob toy with liquid-containing bobs

Abstract

A swinging bob toy having an outer bob and middle bob on a string, with the middle bob having a bore through which the string passes to allow the middle bob to slide along the string. The middle bob has a substantially toroidal, liquid-containing bladder. The mass of the liquid contributes substantially to the overall mass of the middle bob, but the viscosity of the liquid and the dimensions of the bore of the toroid are such that the dynamic moment of inertia (i.e., a moment of inertia dependent on linear and/or rotational velocity and/or acceleration, of a history thereof) is small as the middle bob begins its rotation as the outer bob passes the top of its orbit. The viscosity of the liquid is small enough that as the outer bob traverses the top of its orbit the dynamic moment of inertia is small and the string does not tangle about the middle bob, yet large enough that as the outer bob traverses the bottom of its orbit the rotation of the middle bob is slowed and the string tension does not exhibit a rapid peak.

What is claimed is:  
     
         1 . A swinging bob toy comprising: 
 a flexible, elongated tethering means;    a first end bob; and    a sliding bob having a throughbore along a polar axis normal to an equator in an equatorial plane, said throughbore having a first mouth at a first end thereof and a second mouth at a second end thereof, said tethering means passing through said throughbore of said sliding bob so that said sliding bob is slidable along said tethering means, said first end bob being constrained on said tethering means between said sliding bob and a first end of said tethering means, and said sliding bob having a bladder which encircles said throughbore and contains a liquid.    
     
     
         2 . The swinging bob toy of  claim 1  further comprising a second end bob constrained on said tethering means between said sliding bob and a second end of said tethering means.  
     
     
         3 . The swinging bob toy of  claim 1  wherein said bladder has a roughened interior surface adjacent said first mouth of said throughbore which induces turbulence in a boundary layer of said liquid at a reduced Reynolds number.  
     
     
         4 . The swinging bob toy of  claim 1  wherein said liquid substantially fills said bladder.  
     
     
         5 . The swinging bob toy of  claim 1  wherein said liquid does not fill said bladder.  
     
     
         6 . The swinging bob toy of  claim 1  wherein a portion of said bladder extends from said throughbore to said equator of said sliding bob.  
     
     
         7 . The swinging bob toy of  claim 1  wherein a portion of said bladder extends from said first mouth to said second mouth of said throughbore.  
     
     
         8 . The swinging bob toy of  claim 1  wherein said bladder extends from said throughbore to said equator of said sliding bob, and from said first mouth to said second mouth of said throughbore.  
     
     
         9 . The swinging bob toy of  claim 1  wherein said bladder includes a rigid sheath along said throughbore of said sliding bob and a flexible surface along said equator of said sliding bob.  
     
     
         10 . The swinging bob toy of  claim 9  wherein said flexible surface extends from said first mouth of said throughbore to said second mouth of said throughbore.  
     
     
         11 . The swinging bob toy of  claim 1  wherein said bladder is transparent.  
     
     
         12 . The swinging bob toy of  claim 11  wherein said liquid includes solid particles having a solid density roughly equal to a liquid density of said liquid.  
     
     
         13 . The swinging bob toy of  claim 11  wherein said liquid includes a first fluid of a first color and a second fluid of a second color which is immiscible with said first fluid.  
     
     
         14 . The swinging bob toy of  claim 13  wherein said first color is transparent.  
     
     
         15 . The swinging bob toy of  claim 1  wherein said liquid is water.  
     
     
         16 . The swinging bob toy of  claim 1  wherein said liquid has a viscosity between 10 and 200 centipoise.  
     
     
         17 . The swinging bob toy of  claim 1  wherein said liquid has a viscosity between 25 and 150 centipoise.  
     
     
         18 . The swinging bob toy of  claim 1  wherein said liquid has a viscosity between 60 and 90 centipoise.  
     
     
         19 . The swinging bob toy of  claim 1  wherein a first width of said first mouth is 35% to 55% of a second width of said equator of said sliding bob, and a third width of said throughbore at a depth of one-quarter of a length of said throughbore is 15% to 35% of said first width.  
     
     
         20 . A swinging bob toy comprising: 
 a flexible, elongated tethering means;    a first end bob; and    a sliding bob having a throughbore along a polar axis normal to an equatorial plane, said throughbore having a first mouth at a first end thereof and a second mouth at a second end thereof, said tethering means passing through said throughbore of said sliding bob so that said sliding bob is slidable along said tethering means, said first end bob being constrained on said tethering means between said sliding bob and a first end of said tethering means, and said sliding bob having movable components and non-movable components, said movable components having a movable mass, and said non-movable components having a non-movable mass which is less than said movable mass.    
     
     
         21 . The swinging bob toy of  claim 20  wherein said non-movable mass is less than 80% of said movable mass.  
     
     
         22 . The swinging bob toy of  claim 20  wherein said non-movable mass is less than 60% of said movable mass.  
     
     
         23 . The swinging bob toy of  claim 20  wherein said non-movable mass is less than 40% of said movable mass.  
     
     
         24 . The swinging bob toy of  claim 20  wherein said non-movable mass is less than 20% of said movable mass.  
     
     
         25 . A swinging bob toy comprising: 
 a flexible, elongated tethering means;    a first end bob; and    a sliding bob having a throughbore along a polar axis normal to an equatorial plane, said throughbore having a first mouth at a first end thereof and a second mouth at a second end thereof, said tethering means passing through said throughbore of said sliding bob so that said sliding bob is slidable along said tethering means, said first end bob being constrained on said tethering means between said sliding bob and a first end of said tethering means, said sliding bob having movable components and non-movable components, said movable components having a motion-dependent dynamic moment of inertia and a non-dynamic moment of inertia reflecting a moment of inertia when said movable components are frozen in place relative to said non-movable components, and said non-movable components have a static moment of inertia, and where a first sum of said dynamic moment of inertia and said static moment of inertia is less than a second sum of said non-dynamic moment of inertia and said static moment of inertia.    
     
     
         26 . The swinging bob toy of  claim 25  wherein said first sum is less than 80% of said second sum.  
     
     
         27 . The swinging bob toy of  claim 25  wherein said first sum is less than 80% of said second sum.  
     
     
         28 . The swinging bob toy of  claim 25  wherein said first sum is less than 60% of said second sum.  
     
     
         29 . The swinging bob toy of  claim 25  wherein said first sum is less than 40% of said second sum.  
     
     
         30 . The swinging bob toy of  claim 25  wherein said first sum is less than 20% of said second sum.