I asked the girls the other day if they would like to make a marble roller coaster!?  The answer was YES, but how are we going to do that??? I found this idea on a free app called Instructables ...

It’s actually really easy and would be a ton of fun for a large group of kids, but worked great  for just the three of us and we had a blast. We started off by watching a Brain Pop video and took a quiz on kinetic energy. Then we found a couple of video on youtube.com that explained how a roller coaster works.

http://www.youtube.com/ZH4npnwI0wk

So here is what you need to get started:

• foam pipe insulation from your local hardware store (we used 7/8″  I suggest 1″)
• masking tape
• marbles
• you will also need tables, chairs, boxes, trashcan, anything to help support the roller coaster

We learned about basic physic concepts like, potential energy, kinetic energy, and momentum. The key to making this work is test, test, test, and more testing.  We would position our rails (the foam pipe) in different positions and try  to see if the marble would move through the track correctly before taping anything down.  Then once we were happy with the results we would tape it down and test again to make sure we still liked the outcome.  At one point we were so frustrated with our second roller coaster we had to wait for daddy to get home, or help.

STEP ONE – prep the tubbing ( this will be the rails)  

• Use your finger or scissors to open gap in tube
• Then cut the tube in half with scissors
• you should end up with 2 rails

STEP TWO – starting the roller coaster –  place piece of tape at the end of the tube and affix it to a smooth surface.  This doesn’t have to be pretty, you just want the tube sturdy when place the marble at the end to start the ride. I helped the girls with the first roller coaster and purposely started the drop low to show them it wouldn’t work and then we got a stepping stool to make the drop higher.  It was so exciting when the marble didn’t fly off the rail and actually worked.  The girls tried different size marbles and tried heavier and lighter marbles to see different result.

STEP THREE – connect the track pieces.  Again this doesn’t have to look pretty but make sure it is smooth on the inside of the track.  To connect two pieces tubing together, lay a piece of tape along the middle of the tube with half the tape hanging off. Pick up the second tube and use your finger to press the second piece of track into it. Make sure you tape the underside of the track.

STEP FOUR – secure to a flat surface.  Most of the time the roller coaster need to touch down on a flat surface.  We actually tried it with no support and the marble kept flying off the track. Secure with two small pieces of tape on the sides of the tube.

STEP FIVE – make it awesome Make your track awesome by adding loops, bends, hills, and curves.  When we did our second roller coaster, we made the first fall so deep that it had negative effect. The momentum is so great that it will continue move because of the speed it gained.  The marble kept flying off the track, so we had to lower it slightly and then add hills and curves to slow the marble down and keep it on the track.  We added a loop to our first roller coaster by bending the track upside down and securing the other end. The loop works because of centripetal force.  Centripetal force is like a momentum: it’s when an object keeps moving forward, except that it’s forced into a circular path.