Spring is in the air, so I thought this would be the perfect time of year for our Science Explorers Club to focus on the topic of Energy (potential and kinetic). Before we got to the hands-on fun, we needed to first understand some basic information about energy. What is it? If you were asked to describe energy, what would you tell someone?
Perhaps one of the simplest definitions of energy is that energy is the ability or capacity to do work. And what is work? Work is done when something, regardless of size, moves. In other words, energy is needed to cause motion. Energy itself is generally divided into two categories: Kinetic and Potential. Potential energy is stored energy that is waiting to work. If you were to stretch a rubber band, but not release it, that rubber band would be holding potential energy. You might be surprised to learn that potential energy can be found in many forms – chemical, mechanical, nuclear, gravitational, and electrical. Gasoline, for example, is a chemical form of potential energy. Other examples of potential energy are a cell phone, a car battery, and a ball sitting motionless on a table. Think back to one of our earliest SEC programs on catapults for another example of potential energy. When we pulled the lever (or spoon) back, stretching the rubber band, we created potential energy in the spoon that transformed into kinetic energy when we released the spoon and let the marshmallows pompoms fly!
Kinetic energy, as you may have guessed, is essentially the opposite of potential energy. A good definition might be that kinetic energy is energy in motion that is actually doing work. A baseball being thrown is experiencing kinetic energy. So is a person bicycling down the road. Where gasoline in a can is an example of potential energy, the fire that gasoline creates would be an example of kinetic energy. A ball sitting motionless on a table is a good example of potential energy; when the ball begins to roll along the surface, it exhibits kinetic energy.
Everyone loves a Slinky!
Before we jumped into our own projects, I let our SEC scientists have fun with some energy demonstrations. First, I pulled out my giant rainbow-colored Slinky! The Slinky, which has been around since the 1940’s, provides an excellent example of potential and kinetic energy. When a slinky is sitting at the top of a set of stairs at rest, it is holding potential energy; as soon as it starts to “walk” down the stairs, it is experiencing kinetic energy.
The “Magic Rollback Can”
Next, we watched a demonstration of the “magic rollback can,” as created by the instructions on Steve Spangler’s Science web site. With just a few simple items – coffee can, battery, rubber band, some tape, some paperclips – you can create a magic rollback can of your own. [NOTE: I didn’t have a 9-volt battery on hand, so I just used a C battery.] What is the “magic”? If you roll the can away from you, it will eventually stop in place and roll back to you! How does this work? The battery, which is suspended in the middle of the can by the rubber band, helps to create potential energy by causing the rubber band to wind and twist itself up when you first roll the can. Eventually, the can reaches its maximum potential energy, the rubber band begins to unwind, and the can rolls back to you using kinetic energy.
Let the racer projects begin!
Steve Spangler’s How-To Video
Our main goal for the day was to create our very own “wind-up racers.” Once again, Steve Spangler gave us the instructions we needed to build our racers. And they were fairly easy to put together – most of the SEC scientists had them assembled before I even finished with the instructions (minus a few early mishaps with threading the rubber bands through the wooden spools). And then the testing began! [NOTE: Eventually, the rubberbands will stretch out and not be as effective, so you may need to replace them after a time to get the best and “speediest” results.]
We also did a variation of this project called “Drag Racing Cups.”
Big thanks to our local Bloomfield, CT Starbucks for donating a bunch of paper coffee cups and lids for our project!
Overall, our SEC scientists thought that the Drag Racing cups had more speed than our wooden spool racers. However, they were a tad trickier to assemble. The most difficult part was probably punching the hole in the plastic lid. No matter what utensil we used, someone inevitably cracked through their lid and created a bunch of splits. But thanks to our generous donation from Starbucks, we had cups and lids to spare 🙂