Science Toy XVI Bearing Track

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Science Toy XVI Bearing TrackI made this to help students and teachers alike grasp the 3 odd questions (see the attachment). We use photo gate timers to reveal the correct answer.If the bearings are released from the same height they will have the same speed at the bottom of the first hill and there should be a tie. They will also have the same speed at the end of the race, except the flat track always wins. The bearing on the two track ramp slows down on its way up the second hill but gains almost all of the speed back as it rolls down The answer to all three questions is B. Attached Images Attached FilesQuestions.doc (114.0 KB, 207 views)Dave ReberWadsworth Ohio
Reply:Neat. Always love your science projects you do for your students. Shame more kids don't have instructors who make science interesting.Have you ever built the one where you launch the one ball horizontally and drop the other vertically and have the two collide mid air to show that both drop the same distance due to gravity?.No government ever voluntarily reduces itself in size. Government programs, once launched, never disappear. Actually, a government bureau is the nearest thing to eternal life we'll ever see on this earth! Ronald Reagan
Reply:so which hits the ground first if you drop a marble and bowling ball from 6 ft? tackleexperts.comwww.necessityjigs.comhttps://www.facebook.com/groups/mach...dingequipment/
Reply:If you measure from the center the bowling ball, If you measure from the bottom they tie.  Mac
Reply:Very good teaching tool. I also admire the way you teach your students!! Interesting thing I learned from one of my reloading books was if you fire a bullet over perfectly level ground from a perfectly level barrel and drop a bullet of the same weight at the end of the barrel at the exact instant the fired bullet exits the barrel they will both hit the ground at the same time. No matter the distance traveled they both fall at the same speed.                                                 MikeOl' Stonebreaker  "Experience is the name everyone gives to their mistakes"Hobart G-213 portableMiller 175 migMiller thunderbolt ac/dc stick Victor O/A setupMakita chop saw
Reply:Very cool. A youtube video is in order. Is it possible that the sharp transitions on the hill is robbing too much energy? If you were to make a hill transitions more gradual, similar to the diagrams, would your results be more as predicted?
Reply:Distance traveled on the flat track is shorter, so even if speed remains the same, flat track "wins".No government ever voluntarily reduces itself in size. Government programs, once launched, never disappear. Actually, a government bureau is the nearest thing to eternal life we'll ever see on this earth! Ronald Reagan
Reply:You got itXMT304 (school)SP125+ (home)HF 4x6 BandsawGood judgement comes from experience and much of that comes from bad judgement.
Reply:Yeah, what DSW said.
Reply:Originally Posted by DSWDistance traveled on the flat track is shorter, so even if speed remains the same, flat track "wins"
Reply:That or a flat track with a longer total length to match the one with the hill.This would have been a cool experiment to do using one of the old Machbox car tracks where you could add the loops, hills or whatever using stock pieces to maintain a consistent length. You'd have to use the bearing vs cars to eliminate the friction factor in the cars though..No government ever voluntarily reduces itself in size. Government programs, once launched, never disappear. Actually, a government bureau is the nearest thing to eternal life we'll ever see on this earth! Ronald Reagan
Reply:As said, the straight track has a shorter travel distance.Same input energy for the car/ball, so they should reach the bottom of the hill with the same speed/energy.And although the speed at the end of the track will be the 'same' (the car/ball on the humped track will indeed slow down on the uphill portion and then speed back up again on the downhill portion, there is a slight speed difference from the addition travel distance and thus the slightly longer friction time), the straight track section has a shorter overall travel distance and thus the car/ball will reach the end there first .First part of the tracks are the same.  Same acceleration (due to gravity), same friction, so same velocity at bottom of the hill.Then transition to the 'flat' part of the track.equation of motion:  D = d(i) + v(i) t + 1/2 a t^2ignore friction (air drag and contact friction), so a = zerono initial distance, so d(i) = zeroLeft with equation of motion of a moving object with no friction or acceleration forces acting upon it.D = v x tv on the two tracks is the same, but D is different so therefore t is different.v(1) = v(2)therefore D(1) / t(1) = D(2) / t (2)rearrange:D(1) / D(2) = t (1) / t (2)Measure total travel distance on the 'flat' part of the track (include travel distance up-across-down the 'hump) for track #1 and track #2.Knowing any three parameters, you can then calculate the fourth.  Make sure to use consistent units!my estimate from a single picture over the internet:track #1 = 'straight' track, flat part of track = ~ 40 inches longtrack #2 = 'humped' track = ~48 inches long travel distancet(2) = (48/40) x t(1)t(2) = 1.2 x t(1)If t(1) = 0.5 seconds, then t(2) would equal 0.6 seconds.Give me some numbers and let me know how close my distance time number guesses were.    The best laid schemes ... Gang oft agley ...
Reply:Prolly showing my age, but Hotwheels were Mattel. Matchbox was a competitor. A million dollar ideaXMT304 (school)SP125+ (home)HF 4x6 BandsawGood judgement comes from experience and much of that comes from bad judgement.
Reply:Originally Posted by DSWThis would have been a cool experiment to do using one of the old Machbox car tracks
Reply:Thanks for nice remarks. For those in the over 40 club teaching is so much more interactive than when we went to school. Forhire I to was concerned with the angle but it works perfectly.Moonrise u da man!!!Ignore the flat track and just measure the speed of the marble on the two hill track. Kids think the speed before and after the second hill will be significantly different (slower after the second hill). Yes the marble slows up the second hill but gains its speed back on the way down. Now consider the two tracks together. Correct the flat track is shorter and always quicker. This is not due to length of track but due mainly because the marble stays at a very high speed for the entire run. The two hill bearing slows down going up the hill and then remains at a slow speed for the portion at the top of the second hill before it gains its speed back.The questions on the attached worksheet are tough.Dave ReberWadsworth Ohio
Reply:Originally Posted by mla2ofusVery good teaching tool. I also admire the way you teach your students!! Interesting thing I learned from one of my reloading books was if you fire a bullet over perfectly level ground from a perfectly level barrel and drop a bullet of the same weight at the end of the barrel at the exact instant the fired bullet exits the barrel they will both hit the ground at the same time. No matter the distance traveled they both fall at the same speed.                                                 Mike
Reply:mla2ofusWe do a few activities like what you describe. Google "Shot the Monkey" it is a classic.Here is like one you describe: http://weldingweb.com/vbb/showthread.php...hlight=science The mass of either ball or which one launches or drops they both hit at the same time.Dave ReberWadsworth Ohio