Give Me Energy

April Luehmann                 Zion Lutheran School
                               3840 W. 216th Street
                               Matteson IL 60443
                               (708)747-7490

Objectives:

The 7th and 8th grade students will be able to define, give examples of, and 
differentiate between potential and kinetic energy.

Materials Needed: 
    
    per group for Lab 1
roller skate
wide, flat board (ramp)
spring scale
2 blocks of wood
some form of weight to be added to the skate
meter stick
log sheets with charts to record data

The Lesson:

Begin by asking the students to find what the following 3 things they see have 
in common.  
          Show them:  1.  an electric cord 
                      2.  a can of Mountain Dew
                      3.  a person climbing up a ladder
Leave the three displayed throughout the lesson.  Tell them at the end of the 
lesson and after they have shared their hypotheses that each of the three give 
something energy. 

Strategy:


Hypothetical Situation:
     I was camping one day, and I was given the responsibility  of starting the 
fire.  As I went out searching for fire wood, I found a terrific small log!  It 
was perfect with the exception that it was too long.  I needed to break it.  
(Bring out a thick and long piece of wood and demonstrate an attempt to brace 
the wood, step on it, and show the board would not break.)  Can anyone give me 
suggestions as to how I can improve my potential to break my log?  (List all 
answers on board for later reference.) 

Do LAB #1:

Directions for the student:
1.  Make a ramp with a block of wood and a wide flat board.  Measure the height 
    of the ramp.  Mass a roller skate with a spring scale and record that data.  
    Place the skate at the top of the ramp and release it.  Measure how far the 
    skate rolled, from the bottom of the ramp to the rear wheel of the skate. 
2.  Raise the ramp by adding another block under the long board.  Measure and 
    record the new height.  Repeat the process of rolling the skate and 
    measuring the distance it rolled.  Record results. 
3.  Add weight to the skate.  Measure and record the new mass of the skate.  
    Repeat the process again of rolling the skate down the ramp at each of the 
    two heights and measuring the distance it rolled.  Record results. 
4.  Study the results and draw a conclusion.  
          *Can you give inanimate objects energy?
          *Did the skate have more energy at any one time?
          *How did YOU give that skate more energy?
     ************************************************************

Return to the hypothetical situation and discuss why adding weight or height 
will give you potential energy to break your "log."  Discuss formula of: 
     gravitational Potential Energy = Weight x Height

Stand on a rung of a ladder.  Ask "How can I increase my potential energy?"
Discuss other forms of potential energy:  a bow and arrow with the bow pulled 
back, a skydiver in an airplane, a spring compressed,... 
    Game:  In teams of three, and in 5 minutes, come up with as many examples of 
potential energy as your team can.  Your team will receive one point for each 
example that no other team thought of, so be creative! 

"As I fall off this ladder, I lose potential energy, right?  Where does it go?  
What about that Law of Conservation of Energy?"  Discuss and define kinetic 
energy.  As a class, give examples such as a book falling, water tumbling over a 
water fall, a fist swinging in the air, a baseball player sliding in to home.


Materials Needed: 
    
    per group for lab 2
     1 full pop can
     1 empty pop can
     1 ramp
     3 blocks of wood
     3 cereal boxes or cornstarch boxes
     log pages for results

Do LAB #2:  BOX BOWLING

The goal of this lab is to knock over the empty cardboard boxes, i.e. accomplish 
WORK.  (Remember work is defined as a force applied through distance.)  From the 
discussion of kinetic energy get the students to remind you that kinetic energy 
is the energy of motion used to do work.  Ask the students to try different 
things to do the MOST possible work (knock over as many boxes as possible). 
     Rules of the lab:
          1. All work must be done by a rolling can.
          2. Can must be LET GO, not pushed or pulled.
          3. Record every attempt you made and the data you measured. 
          *********************************************************

Finish by comparing the results of all the groups.  Give them the formula for 
kinetic energy:
     KE = 1/2 x mass x velocity2

Knowing this formula, discuss which makes a greater impact on the amount of 
kinetic energy, increasing the mass or increasing the velocity.  (Answer: 
increasing the velocity). 

Performance Assessment:

The students will receive points based on demonstrated effort, care in measuring 
results and recording data, and logical and complete support for the conclusions 
they claim to be true.  The students will also be asked to give a VISUAL example 
of both potential and kinetic energy and explain the difference between the two.