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Potential energy can be stored in a variety of different systems. Typically potential energy is stored based on the relative position of one object to another or the change in an object's position. In this lab we will be storing energy in the compressed spring (EPE) and the gravitational field of the Earth (GPE). The energy will be transferred from the compression of the spring to the field of the Earth through the motion (Kinetic Energy) of the cart quantified by the cart's velocity.
∆x = 0 m ∴ F= 0 N
∆x = 0.10 m ∴ F= 3.4 N
In this case we can see that a force of 3.4 N was needed to extend a spring 0.10 m.
Work is being done on the system, W=FΔd, therefore energy is being put INTO the spring.
In this activity we would like to explore various springs and quantify the amount of energy stored in each spring when compressed.
The video will provide background on determining the SPRING CONSTANT. It is this value that we will record for our two different springs.
Converting Elastic Potential Energy to Gravitational Potential Energy
Converting Elastic Potential Energy to Gravitational Potential Energy
Does doubling the compression of the spring double the height the cart reaches on the ramp?
Sketch a diagram of your setup, labeling the significant variables on the diagram.
Indicate 3-5 positions on the sketch that will be significant in your experiments. (i.e. max height of the cart)
Draw Energy Pie Charts at the significant positions on the sketch.
Data Sampling Set-up
Data Channels - Position and Force
Data Collection Rate - Determine the data collection rate that would be best for your experiment.
Zero Sensors -
With the cart resting on the stop, zero the position of the cart.
When the cart is NOT in contact with stop, zero the force sensor.
Conceptual understandings of the graphs.
Take a sample data set.
Match positions on the graph with the 3-5 positions on your sketch.
Determine the spring constant of your spring steel.
Five compression distances (∆x) and Force (N).
Determine slope/gradient of the trendline.
Determine height reached when spring is compressed to five different distances (∆x) and change in height of the cart (∆h).
How will you determine the change in height of the cart (not the distance traveled)?
Create a graph (manually or in Sheets) of height (y-axis) vs. compression (x-axis).
For each of the compressions, determine the maximum velocity when the cart is launched by the spring.
Create a graph (manually or in Sheets) of maximum velocity (y-axis) vs. compression (x-axis).
Typically for all of your data you should collect 5x3 data, however in the interest of time, we will only collect one trial.
Sample Data
Sample Data
Force vs. Compression of Spring Steel
Max Velocity vs. Compression of Spring Steel
Height vs. Compression of Spring Steel
Height vs. Compression of Spring Steel Distance Squared
Some Additional Resources:
Some Additional Resources:
Determining the Energy Stored in a Spring
Determining the Energy Stored in a Spring
Suppose each of the springs were to be used to launch six identical 0.050 kg steel marbles vertically into the air.
To test the system, initially the springs were compressed 0.050 m(x). Once the launching mechanism became fully operational the springs were compressed to 0.100 m (2x) and 0.150 m (3x).
Compare test heights v the fully operational heights reached by the 6 marbles.
You may find the information on 01.3b - Graphical Analysis useful.
Converting EPE to KE to GPE - Goal-less problem
Converting EPE to KE to GPE - Goal-less problem
Choose one of the Goal-less problems below or create your own. Both Pivot simulations have been assigned, you can explore both before making a decision as to which one you choose. OR go purely mental and choose Just a Ball, a Ramp and a Spring. OR if you are up for the challenge find your own spring and object and try one yourself. OR try your hand at being a Bungee Jump operator, (Goal #1 nobody hits their head)
This is a goal-less problem. You are to decide what models (types of energies) apply (state this explicitly and justify your choice), describe any assumptions you are making, and solve for as many unknowns as you can, making good use of written explanation, graphs, energy pie charts, and diagrams.
Prob #2: Einstein on a Joy Ride
Prob #2: Einstein on a Joy Ride
Prob #4: Bungee Jumping
Prob #4: Bungee Jumping
The study of energy has described three energy storage formats based on position, velocity and compression or extension. Be sure to include explanations of transfers amongst these different stores.
Diagrams should include
variables affecting the outcome of the trial.
energy pie charts of relative energy values at key points in the action.
motion maps showing relative velocities at key points.
Graphs should include:
key points that describe the relationship
analysis of the slope (units and values) - if applicable
area under the curve (units and values) - if applicable
The student’s job is to model the situation as best they can using the physics they know. First step: say which models apply and why. Second step: draw (and annotate) the graphs/diagrams that go with those models to represent the situation. Third step: use the diagrams to analyze the situation.
Kelly O'Shea - Goalless Problems
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