Acceleration due to gravity

Abstract
The purpose of this lab is to calculate the acceleration of gravity using the Smart Timers. Drops of ball of equal size and start drops at one hundred centimeter height, the amount of time was counted used the Smart Timers. Repeat the same procedure ten times; the amount of times was counted used the Smart Timers.

After compared these data were compared, result is the data has about 0.01-second error. The most likely reason is the height is not constant, the each ball drops from approximately one hundred-centimeter height.

Theory
The height of a free falling object can be calculated using the following formula: Y = Y0 + V0t – 1/2 * gt­­­­­2, Note: Y – Y0 =the height. Using this formula, it will be up to solve for “g” and show that formula: g = 2(Y – Y0)/ t2. Follow the formula Y – Y0 =the height, so the Y – Y0 = 100cm. Then using the times data that got from the tests. The result of calculates, it got the several different “g”, take an average. Throw out an extremely large or small value.

Hypothesis
This lab was designed to calculate the acceleration of gravity using the Smart Timers. The theory predicts that g = 980cm/s2. In the class, the “g” most time is considered to be 9.8m/s2. Materials

Yellow plastic ball
The Smart Timers
Iron Bracket
Clamp
Target pad
Photogate

The yellow plastic ball is as subjects. Iron Bracket use to constant the height, and clamp use to stable the Smart Timers attached on the Iron Bracket. The Smart Timers is use to count the amount of time. Target pad is part of the Smart Timers, it use to when ball fall on it, it will back to Smart Timers to make it stop timing. Photogate also the part of the Smart Timers, it use to back to Smart Timers the ball start drop, to make Smart Timers start timing.

Procedure
First check the height is 100cm; place the photogate with the bar and attached it to the lower clamp on the main bar-stand. Place the plug from the photogate to the #1 spot on the smart timer. Tightened the clamp so that it is perpendicular to the main bar stand. And make sure place the “pad” on the floor directly below the photogate, also do not step on the pad. Connect the plug from the pad to the spot on #2 spots on the smart timer. Then turn on the smart timers, now press #1 “button” to “time”. Now press the #2 button 3 times until it says “2 gates”.

After below the step, push the “3 Button” twice until a “star” shows up and take the “yellow” plastic ball and position it near the photogate. After pressing “3” start/stop button twice until a “star” appears on the screen, release the yellow plastic ball and measure the time it takes to fall. Do this 10 times and take an average. Throw out an extremely large or small value.

Data
The following chart details the ten times trials of the experiment and includes an average of the ten times trials. The average of the ten times trial; throw out an extremely large or small value.

Data Analysis
The data collected show the ten times amount of time that yellow plastic ball fall on pad, the all ball is drop from the same height. The data also show the average value of time and “g”. (Throw out an extremely large or small value)

The result have an anomalies, it’s much bigger than the prediction that g = 980cm/s2. It has a considerable error with prediction. The new hypothesis need to make sure the ball is drop from the same height, use hands to begin the drops will be have too much error, choose a heavier ball, to reduce the impact of air resistance. Shorten the connect line both between the photogate and smart timers, and pad and smart timers.

Error Analysis
The result has a considerable error with prediction. The most likely cause is air resistance and height not content. Use hand to start drop the ball is hard to constant the height, here will have some error, and plastic ball may too light, it is susceptible to get effect by the air resistance. Also the smart line connect line data transmission time will be effect the result, but this time is almost negligible, and under the present conditions, it is no way to improve that much.

The data result with prediction has about 47.83% errors.

Conclusion
The experiment is to calculate the acceleration of gravity using the Smart Timers. In the conclusion, this lab seems to didn’t have generated strong support for the theories and hypothesis that g = 980cm/s2. The error make the result with forecast has a large gap. Air resistance and height is just relatively constant are the most reasons.

Set a constant height will be better than use hands to drops the ball. Change the yellow plastic ball to an iron ball or other heavier ball will be much decreases the effect from air resistance. And have more tests will be better to confirm the results, if each personal do the ten times, then compare the each result, more tests is help to reduce errors.