Energy Conservation Model

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Dean Reese (Author)

WHAT IS IT?

In the NGSS there is the following high school Physical Science standard: HS-PS3-1 Create a computational model to calculate the change in energy of one component in a system when the change in the energy of the other components and energy flows in and out of the system are known. This a NetLogo simulation that was built to show one possible example of fulfilling this performance expectation. This also encompasses the following Science and Engineering Practices from the NGSS: 2. Developing and using models, 5. Using mathematics and computational thinking, and 8. Obtaining, evaluating, and communicating information.

HOW IT WORKS

This model uses the concept that Kinetic Energy = 1/2 m v^2 and Potential Energy = m g h to illustrate conservation of mechanical energy. Time ticks away in .0001 second increments and Kinetic Energy, Potential Energy, Velocity and Position of a falling object are updated.

HOW TO USE IT

Choose the initial height of the falling box and the mass of the box. Then press setup and go. This will allow the box to fall from the desired height and also plot the Kinetic Energy, Potential Energy and Total Energy of the System.

THINGS TO NOTICE

One thing to notice is that the Total Energy of the system remains constant throughout the simulation. Interestingly, the sum of Potential Energy + Kinetic Energy (Total Energy) is not programmed into the code. Instead this is a property that emerges from the simulation validating the Law of Conservation of Energy in this ideal state.

EXTENDING THE MODEL

One possible extension to this model would be to include the loss of Kinetic Energy due to air resistance. This should result in a decrease in Total Energy over time for the Box's Mechanical Energy. Another possible extension of the model would be to have the box launched from a spring into the air, keeping track of Spring Potential Energy, Gravitational Potential Energy and Kinetic Energy of the box.

CREDITS AND REFERENCES

Conservation of Mechanical Energy NetLogo Simulation by Dean Reese is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License.

Comments and Questions

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Click to Run Model

; This is a Conservation of Mechanical Energy model made by Dean Reese - dreese@tusd.net, Teacher at Tracy High School,
; Instructor for the SIMMS Project, and Instructor for LLNL's Computer Simulation Teacher Research Academy.  


globals [K U v g t]                                   ; defines the following variables: K - Kinetic Energy, U - Potential Energy, v - velocity, g - gravity, t - time

to setup                                              ; procedure for the setup button
  clear-all                                           ; restarts the world to the default setting
  reset-ticks                                         ; establishes a clock and sets clock to zero
  ask patches [set pcolor 98]                         ; sets background color
  create-turtles 1                                    ; creates the falling object
  [set shape "box"                                    ; sets shape to box
   set size 1.2                                       ; sets size of box to 1
   set color red                                      ; sets color of box to red
   set heading 180                                    ; sets direction of box to point down initially
   set xcor 5                                         ; sets x-position of box to 5
   set ycor height]                                   ; sets y-position of box to height chosen by the height slider
  
  set v 0                                             ; sets the initial value of velocity to 0
  set g 10                                            ; sets the value of gravity to 10
  set t 0                                             ; sets the initial value of time to 0
  set K .5 * mass * v * v                             ; sets initial Kinetic Energy value to be 1/2 m v^2
  set U mass * g * height                             ; sets initial Potential Energy to be m g h
end 

to go                                                 ; procedure for the go button
  every .0001 [set t t + .0001]                       ; allows time to tick up by increments of .0001 seconds for a smooth transition on graphs
  set v (g * t)                                       ; updates velocity every .0001 s via the equation vf = vo + a t
  set K .5 * mass * v * v                             ; updates Kinetic Energy every .0001 s via the equation 1/2 m v^2
  set U mass * g * ([ycor] of turtle 0)               ; updates Potential Energy very .0001 s via the equation m g h
  ask turtle 0 [set ycor ( height - (5 * t * t))]     ; updates the height of the box via the equation yf = yo + vo t + 1/2 a t^2
  if t >= sqrt ((2 * height) / g) [ stop]             ; stops the program when the box reaches the bottom of the frame via t = sqrt (2 height/g)
  tick                                                ; ticks ahead one iteration of the go procedure   
end

There is only one version of this model, created almost 9 years ago by Dean Reese.

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