Vice Versa Balls - DuneCraft

SMART TUBES Ages 5+One Bounces, One Won’tUsed ByMagicians!ContainsOne Rubber Ball Making KitWARNING: CHOKINGHAZARD-small partsnot suitable for childrenunder 3 years©2005 DuneCraft, Inc.Chagrin Falls, Ohio44022Plus–Make Your OwnBouncing Balls!Visit www.dunecraft.comfor more informationHow to Make YourOwn Bouncing BallThis kit comescomplete with abouncing ball mold,2 colors of crystal powderto make 2 bouncing balls,and detailed instructions.Just add water and instantlymake your own bouncingballs! See how high theybounce.These balls may look and feel like twoidentical rubber balls, but don’t be deceivedby what you see. One bounces andthe other doesn’t! This kit also includeseverything you need to make yourown bouncing balls!Fun Facts• Butyl rubber (like in the no-bounceball) is used to make running shoesthat absorb energy. This keeps therunners’ knees and ankles healthy byabsorbing the damaging shock!• There are many kinds of materialsthat “remember” their original shapeand return to it after being bent.There are metal shape-memoryalloys (SMAs), shape-memorypolymers (SMPs), and shape-memoryceramics (SMCs).• SMAs (metal shape-memory alloys)are currently used commercially andare being used in new medicalequipment.• Used as a magic trick for years!• You can make your own bouncingballs in minutes.

Experiments with12increase, decrease or remain constant?31Drop each ball simultaneously from 12 inches.1Which one bounces?1Once 2Once 2 you determine which ball bounces, drop2the 2increase, ball from 12 inches. Observe how highthe ball bounces each time. Does the heightdecrease or remain constant?3Compare3the height the bouncing ball reaches3after dropping it from 12 inches, 24 inches and336 inches.How it WorksA ball held in the air has the potential to movewhen released, which is called potential energy.When the ball is dropped, gravity pulls it towardsthe center of the earth. The energy of the movingball is called kinetic energy. When the rubber ball’sdescent is stopped by the floor, it is slightly flat-tened as the particles squeeze together. (Imagineif you dropped a ball of soft clay on the ground-would it remain a ball or would it spread out on theground?) Some of the kinetic energy the ball hadon the descent becomes elastic potential energy.What happens next is determined by the proper-ties of the ball.Though they look the same, each ball is made ofa different material. The ball that bounces is madeof a natural rubber. The natural rubber polymer’smolecules are crossed linked by another sub-stance. This prevents the molecules of rubber toslide past each other when a force is applied tothe ball. When it makes contact with the ground,it flattens momentarily before bouncing back to itsoriginal shape. The upward energy created whenit returns to its normal height causes the entireball to bounce upward again. The process repeatsitself until the ball has no more energy, and comesto a stop.The no-bounce ball is made of butyl rubber. It actsjust like the bouncing ball, except it absorbs moreof the energy. The energy that makes the bounceball bounce again is absorbed by butyl rubber,4height you released it at?54Carefully throw bouncing ball at the ground4(not too hard- it could hurt someone or knock4something over!) Does it bounce higher than the4height you released it at?5Mark 5 which ball is the bouncing ball and which5one is not. Put both balls in a freezer for 10minutes. Drop each from 12 inches. Whathappens? Does the bouncing ball still bounce?“Race” each ball down a slight incline. Whichwins the race?wins the race?6 highest?6Try dropping the two balls on a “soft” chair or6firm foam surface. Which ball now bounces thehighest?so it “dies” almost immediately. This is becausethere are no cross-links between the butyl rubber.When a force is applied the molecules slide pastone another. The energy went into deforming theball. Butyl rubber is used as shock absorbers inmaterials such as inserts for runner’s shoes andmotor mounts.When frozen, the balls reverse- that is, the ball thatis supposed to bounce dies immediately and theball that isn’t supposed to bounce does! The coldtemperature slows the movement of molecules ineach ball, thus reversing the characteristics. Letthe balls return to room temperature, and they willbehave as expected.Conservation of energyYou should have noticed that the bouncing ball doesnot bounce higher than it was originally dropped.This is because of Conservation of Energy. Thisimportant law of physics states that energy is nei-ther created nor destroyed, it only changes fromone form to another. With the bouncing ball, theenergy changes from potential energy (before it isdropped) to kinetic energy (while it is moving) toelastic potential energy (while in contact with theground.) When the ball touches the ground, someof the energy is transferred to the ground. The balltherefore has less energy, and does not bounceas high. When the ball is thrown with some force,however, it gains energy from the floor and is ableto bounce higher.