Atwood's Device Lab
Partner: Madeline Walbert
Date: 11/17/14
Purpose:
In this lab, we will determine the acceleration of two masses on Atwood's Device by keeping a constant net force.
Date: 11/17/14
Purpose:
In this lab, we will determine the acceleration of two masses on Atwood's Device by keeping a constant net force.
Theory:
Atwood's Device is named after the man who invented it, the Reverend George Atwood. He constructed it to demonstrate and verify certain laws of motion under laboratory conditions. The mechanism consists of of a pulley system with two masses suspended from a string. By applying Newton's second law of motion, it can be calculated that when the two masses are unequal, acceleration will result as the larger mass falls down and the smaller mass is pulled up and that this acceleration will be constant for both masses. This is what would take place under ideal conditions and does not take into account friction or the tendency of any string or wire to stretch.
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Variables used:
g=Acceleration due to gravity ΣF1=Sum of the forces on the first object ΣF2=Sum of the forces on the second object W1=Weight of first object W2=Weight of second object T=Tension m1=Mass of first object m2=Mass of second object a=Acceleration Percent Difference= How different the two values are from one another exp1=Experiment one exp2=Experiment two |
Experimental Technique:
First we assembled Atwood's Device and proceded to derive the equation in order to calculate the acceleration of the two masses. The masses had a constant net force for each new trial, meaning the masses changed in the same increments so that the difference in the masses were always the same.
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After six trials of acceleration were calculated using the derived equation, the process of finding acceleration was repeated but this time with DataStudio's Motion Sensor. The position vs. time graph was depicted to be the most accurate out of the three graphs (velocity vs. time and acceleration vs. time being the other two). In order to find acceleration using this graph, the part of the graph that was of the masses moving with the system (not bouncing off the carpet surface) had to be highlighted in order to pull up an equation. Looking at the equation, part A had to multiplied by two and then that value equaled the acceleration. Lastly, after all of the trials were conducted for both experiments, the percent difference was found. Since the percent difference happened to be very large, a seventh trial was conducted with a greater net force in order to minimize the percent difference.
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Data and Analysis:
Trial 7 was the attempt to fix errors.
Conclusion:
Overall, the acceleration values from the derived equation and the values from the Motion Sensor were solved correctly, but there was still a high percent difference. In order to overcome this setback, a seventh trial was conducted. In this seventh trial, a larger net force was used, 50g instead of 5g, to reduce the percent difference down to 11%. One reason for the high percent difference values is the weight. As the acceleration increased, the masses decreased. As the masses increased, the percent difference increased as well, even though the net force stayed the same the entire time. With a larger net force, the acceleration increased this time, creating a lesser percent difference value.
Overall, the acceleration values from the derived equation and the values from the Motion Sensor were solved correctly, but there was still a high percent difference. In order to overcome this setback, a seventh trial was conducted. In this seventh trial, a larger net force was used, 50g instead of 5g, to reduce the percent difference down to 11%. One reason for the high percent difference values is the weight. As the acceleration increased, the masses decreased. As the masses increased, the percent difference increased as well, even though the net force stayed the same the entire time. With a larger net force, the acceleration increased this time, creating a lesser percent difference value.
References:
Bowman, D. (n.d.). Lahs Physics. Lahs Physics. Retrieved November 24, 2014, from http://lahsphysics.weebly.com/
Giancoli, D. (1998). Physics: Principles with applications (5th ed.). Upper Saddle River, N.J.: Prentice Hall.
Petersen, C., & Barwick, S. (2014, October 19). What is the Atwood Machine? Retrieved November 24, 2014, from http://www.wisegeek.com/what-is-the-atwood-machine.htm
Bowman, D. (n.d.). Lahs Physics. Lahs Physics. Retrieved November 24, 2014, from http://lahsphysics.weebly.com/
Giancoli, D. (1998). Physics: Principles with applications (5th ed.). Upper Saddle River, N.J.: Prentice Hall.
Petersen, C., & Barwick, S. (2014, October 19). What is the Atwood Machine? Retrieved November 24, 2014, from http://www.wisegeek.com/what-is-the-atwood-machine.htm