Unit 7 -- Energy (With Less Work)

We started the Energy unit by being posed the question "What is energy?"  We came up with some basic answers, and it led to the 1st rule of energy:  "All energy is stored.  It must be stored someplace (a real place) and we can "see" something about it."  Energy was discussed as a transfer of information and energy as currency.  Currency or information can change form but it is still currency or information. 

A few other questions had to be established, such as "Where is energy stored?", "Where does it come from?", "Where does it go?", and "What does energy do?"  This was the lens we had to look through to see if what we thought was energy really was energy. 

We looked at a battery operated dune buggy and established the system as the dune buggy, the battery and the surroundings.  We drew pie charts to represent the energy Before it starts moving, another to represent After it starts moving and another to represent After it moves for two minutes.  Then we did the same thing with other systems on a worksheet. 

We noticed that energy is really just a book keeping term to keep track of and make sense of the world. 

Next we did a lab looking at the relationship between the distance a spring is stretched and the force applied.  We noticed a direct linear relationship and different groups had different types of springs.  After we were looking at the graphs, we were asked "Where is the energy?"  We noticed it was not in the slope - that represented the tightness of the spring, and the energy is not in the values - that represented the stretch distance and the force.  We were led to look at the area under the curve and that was determined as the elastic energy.  We established Hooke's Law and the formula for Elastic Energy in this experiment. 

We then looked at L O L energy flow diagrams where we would see the initial energy condition , the energy flow diagram (the system) and the after condition.  Energy was shown as blocks and if you start with four blocks, you would have to account for all four blocks somewhere. 

We then looked at the following relationships and did experiments and whiteboards and discussed them.  "What is the relationship between energy stored in rubber band and velocity?" , "What is the relationship between energy stored in rubber band and vertical height?" , and "What is the relationship between energy stored in rubber band and slide distance of friction block?"  The setup of these experiments had a rubber band stretched between two C-clamps with a track between the C-clamps so that the cart would bounce back off the rubber band.  We first had to find the spring constant of the rubber band and then looked at the following relationships.  These experiments helped us to establish the formula for Elastic energy and kinetic energy and gravitational field energy.