How to determine the acceleration due to gravity —by dropping water  AS3  Zoe
Equipments and meterials <ul><li>Equipment </li></ul><ul><li>burette, 25 ml or larger  1 </li></ul><ul><li>support stand, ...
Hints for a successful lab <ul><li>Be sure to keep the burette filled to a relatively constant level between 10 mL and 15 ...
Setup the burette and pan <ul><li>1. Use the support stand and 3-prong clamp to hold the burette. </li></ul><ul><li>2. Pos...
Adjust the drip rate   <ul><li>1. Adjust the valve on the burette so that the time it takes one drop to fall is equal to t...
Measure the drip rate <ul><li>1. Measure the time it takes 10 drops to fall and record it on the data sheet. </li></ul><ul...
Data sheet 3 2 1 Burette to Pan Distance (m) Elapsed Time for 1 Drop (s) Elapsed time for 10 drops(s)
Calculation  <ul><li>We use the following two equations to calculate the acceleration due to gravity (g). </li></ul><ul><l...
<ul><li>Source of errors </li></ul><ul><li>1.Air resistance </li></ul><ul><li>2.Measure the time </li></ul><ul><li>Reliabl...
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AS3/ Expt-g/ Zoe

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AS3/ Expt-g/ Zoe

  1. 1. How to determine the acceleration due to gravity —by dropping water AS3 Zoe
  2. 2. Equipments and meterials <ul><li>Equipment </li></ul><ul><li>burette, 25 ml or larger 1 </li></ul><ul><li>support stand, with 1/2” rod 1 </li></ul><ul><li>3-prong clamp 1 </li></ul><ul><li>rod clamp 1 </li></ul><ul><li>meter stick 1 </li></ul><ul><li>Materials </li></ul><ul><li>pie plate, disposable aluminum 1 </li></ul><ul><li>paper cup, 5 oz. 1 </li></ul>
  3. 3. Hints for a successful lab <ul><li>Be sure to keep the burette filled to a relatively constant level between 10 mL and 15 mL. </li></ul><ul><li>Adjust the drip rate by watching drops emerge from the burette while listening to drops hitting the pan. </li></ul><ul><li>Measure the time it takes ten drops to fall rather than just one drop. </li></ul><ul><li>Start timing when you hear drop one hit the pan and stop timing when you hear the tenth drop hit the pan. </li></ul>
  4. 4. Setup the burette and pan <ul><li>1. Use the support stand and 3-prong clamp to hold the burette. </li></ul><ul><li>2. Position the burette so that it hangs over the edge of the table top, allowing drips to fall into an aluminum pie pan on the floor. </li></ul><ul><li>3. Adjust the drip rate of the burette until one drop strikes the plate on the floor at the same time a new drop starts to fall. </li></ul><ul><li>4. Use the paper cup to fill the burette with 10-15 mL of water. </li></ul>
  5. 5. Adjust the drip rate <ul><li>1. Adjust the valve on the burette so that the time it takes one drop to fall is equal to the time between drops. </li></ul><ul><li>2. Adjust the drip rate until a drop forms and begins to fall just as the previous one hits the plate. </li></ul><ul><li>3. Check that the water level in the burette is between 10 mL and 15 mL. Add water as needed. </li></ul>
  6. 6. Measure the drip rate <ul><li>1. Measure the time it takes 10 drops to fall and record it on the data sheet. </li></ul><ul><li>2. Calculate the time it takes one drip to fall and record it on the data sheet. </li></ul><ul><li>3. Check that the water level in the burette is between 10 mL and 15 mL. Add water as needed. </li></ul><ul><li>4. Empty the water from the pie pan. </li></ul><ul><li>5. Repeat the measurement three times. </li></ul>
  7. 7. Data sheet 3 2 1 Burette to Pan Distance (m) Elapsed Time for 1 Drop (s) Elapsed time for 10 drops(s)
  8. 8. Calculation <ul><li>We use the following two equations to calculate the acceleration due to gravity (g). </li></ul><ul><li>h = gt*t/2 </li></ul><ul><li>g=√2h/t*t </li></ul>
  9. 9. <ul><li>Source of errors </li></ul><ul><li>1.Air resistance </li></ul><ul><li>2.Measure the time </li></ul><ul><li>Reliable </li></ul><ul><li>Generally says, this experiment is reliable, because we repeat this experiment for three times, and take the average value finally. So we can decrease the random errors, like the errors when we measure the time. But there is also some systematic errors, like the air resistance. As we known, Air resistance increases as it speeds up. But if the distance between burette and pan should not be long, we can ignore the air resistance </li></ul>

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