Julia+and+Hannah's+Roller+Coaster+Lab

=Conservation of Energy on a Roller Coaster= September 28, 2009
 * Participants**: Julia Kravitz and Hannah Mollmark
 * Purpose**: The purpose of this lab is to examine how mechanical energy (kinetic and potential energy) can be changed by outside forces.
 * Lab Documents**: [[file:Roller Coaster.doc]]


 * Brief Description of Experiment**: In this experiment, Hannah and I, as well as the remainder of the class, observed and made measurements of a cart's movement while traveling on a roller coaster track. We measured the height, speed, time, distance, and mass of the cart. The height was of the cart at a point down to the base of the roller coaster. The speed was measured at those same points. The distance was given to us, and the mass of the cart was measured on a scale. After finding all of these measuements, we plotted them on a graph. We also added to the graph Kinetic Energy, Potential Energy, and the Total Mechanical Energy.


 * Data**:

KE = 1/2 x mass x velocity x velocity || PEgravity = mass x gravity standard x height || ME = KE + PE || W = F x d OR W = ∆ KE ||
 * Sample Calculations:**
 * //Kinetic Energy Calculation// || The kinetic energy in joules was calculated by mulitplying one half by the mass in kilograms of the cart by the velocity of the cart squared, which is meters per second.
 * //Potential Energy (of gravity) Calculation// || The potential energy in joules was calculated by mulitplying the mass in kilograms of the cart by 9.8m/s sq. (standard gravity) by the height in meters of the cart.
 * //Mechanical Energy Calculation// || The mechanical energy in joules was calculated by adding together kinetic energy in joules and potential energy in joules.
 * //Work Calculation// || Work was calculated by multiplying the force by the distance it was applied. Or the change in kinetic energy.


 * Results**: The purpose of the lab was to observe how mechanical energy can be changed by outside forces. The lab was successful because the changes in energy could be seen in the changes in the track direction and design. When the potential energy, kinetic energy, and mechanical energy are all graphed, the changes in energy forms can be observed in comparison to the design of the roller coaster track such as turns, loops, and degrees of slopes. Due to the changes in the track, the gravitational potential energy varies as well because of the different heights. The result was reached by measuring mass, height, and speed and then creating calculated columns on LoggerPro to determine the kinetic energy (1/2 x mass x velocity x velocity ), potential energy (mass x gravity standard x height ), and mechanical energy (KE + PE ).

1. What external forces did you identify as removing energy from the roller coaster system? Into what form of energy do you think the mechanical energy was converted via these forces? An external forces that removes energy from the roller coaster system is gravity when the cart on the track moves upward (in the loop) because gravity will push down on it. When acted upon by this external force, the mechanical energy is converted into gravitational potential energy.
 * Lab Questions**:

2. What external forces did you identify as adding energy to the roller coaster system? From what form of energy do you think the mechanical energy was converted via these forces? The external forces that add energy to the roller coaster system are the motorized band that pulls the cart up the ramp and gravity pushing down on the cart when the track has a downward slope. These forces were converted from potential energy because the ramp has stored forces or the //ability// to move the cart once in contact with it. Also, the cart has gravitational potential energy because at the beginning of the roller coaster it is at a higher point on the track which increases the potential energy of gravity.

3. Break the motion of the coaster into 4 pieces as described below. What fraction of the total mechanical energy from the top of the coaster was lost in: a. The first big drop Point 8: 0.55j - 0.354j = 0.196j 0.196j/0.55j = 0.356 = 35.6%

b. The entrance to the loop Point 8: 0.55j - 0.354j = 0.196j 0.196j/0.55j = 0.356 = 35.6%

c. The exit of the loop Point 16: 0.55j - 0.222 = 0.328j 0.328j/0.55j = 0.596 = 59.6%

d. The back turn Point 24: 0.55j - 0.123j = 0.427j 0.427j/0.55j = 0.776 = 77.6%

4. At what point in the motion of the roller coaster was mechanical energy being dissipated (lost from the system) most quickly with respect to distance traveled? How about with respect to time? From point 7 to point 8, 0.421 joules of mechanical energy was lost in a distance of 0.18 meters and a time of 0.03 seconds.

This Roller Coaster lab was done in order to study how mechanical energy, which is the sum of potential energy and kinetic energy, can be influenced and changed by outside forces. We think that the experiment produced a valid and reproducible result because the calculations were all based on simple measurements of the actual roller coaster track which does not change. Our experimental results differ slightly from accepted or expected results due to some human error in measuring heights and speeds. Because the class did all the measurements as a group, people might have had slightly different measuring techniques. In addition, when time was being measured from the start of the track, it is hard to accurately press the start and stop button at the exact points. In order to improve on the experiment, if more time were available, one person could do all the measurements to decrease the chance of inaccuracies and a better timing technique could be determined.
 * Conclusion**:

//Don't forget to link to your lab report from the lab reports page and to include a link to your lab report in your reflection.//