Determine  the  g  by  using  a  light  gate 10.1  2009
Overview  <ul><li>In this experiment, a “double interrupt card” is dropped through a single light gate. The time at which ...
Apparatus and materials <ul><li>Light gate, interface and computer   </li></ul><ul><li>Weighted card   </li></ul><ul><li>C...
The  diagram  of  the  apparatus
Procedure.  <ul><li>1. Assemble the apparatus as shown. 2. Connect the light gate to Input A on the datalogger. 3. Connect...
<ul><li>7.Repeat the experiment many times and when enough  readings have been taken, stop recording by clicking on  the r...
How  to  achieve  the  number  of  the  g ? <ul><li>In  each  experiment , we  measure the  width of  the  whole card as  ...
<ul><li>From  the  experiment  ,we can  write  following  equations: </li></ul><ul><li>a=u 1 t 1 +1/2 g t 1 2  ①  </li></u...
<ul><li>In  the  ①, we  can  infer  that  </li></ul><ul><li>u 1 =(a-1/2gt 1 2 )/t 1  ④ </li></ul><ul><li>In  the  ② , we  ...
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AS3/ Expt-g/ Stephen

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AS3/ Expt-g/ Stephen

  1. 1. Determine the g by using a light gate 10.1 2009
  2. 2. Overview <ul><li>In this experiment, a “double interrupt card” is dropped through a single light gate. The time at which each break of the infrared beam occurs is recorded. With knowledge of the width of the interrupt card, the software can determine the velocities at key stages of the fall and use these increasing values of velocity to calculate acceleration. Several trials will be conducted and an average value found. </li></ul>
  3. 3. Apparatus and materials <ul><li>Light gate, interface and computer </li></ul><ul><li>Weighted card </li></ul><ul><li>Clamp and stand </li></ul>
  4. 4. The diagram of the apparatus
  5. 5. Procedure. <ul><li>1. Assemble the apparatus as shown. 2. Connect the light gate to Input A on the datalogger. 3. Connect the datalogger to the computer and launch the Timer program. 4. Set the Timing software to record Acceleration at A in repeat mode. 5. Enter the length of the segments on the interrupt card when prompted (the segment is the solid section of the card that will pass through the light gate). 6. Begin recording and then drop the interrupt card ensuring that the light beam is broken by each section of the card. </li></ul>
  6. 6. <ul><li>7.Repeat the experiment many times and when enough readings have been taken, stop recording by clicking on the red square. 8.Delete any obviously obscure measurements. 9.Save your results in the recommended folder 10. Calculate the average acceleration. </li></ul>
  7. 7. How to achieve the number of the g ? <ul><li>In each experiment , we measure the width of the whole card as l and the width of each interrupt part as a. </li></ul><ul><li>The transit time Where light beam is broken by each section of the card will be measured and we denote them as t 1 and t 2 . </li></ul>
  8. 8. <ul><li>From the experiment ,we can write following equations: </li></ul><ul><li>a=u 1 t 1 +1/2 g t 1 2 ① </li></ul><ul><li>a=u 2 t 2 +1/2 g t 2 2 ② </li></ul><ul><li>2g(h-2a)=u 2 2 -(u 1 +gt 1 ) 2 ③ </li></ul>
  9. 9. <ul><li>In the ①, we can infer that </li></ul><ul><li>u 1 =(a-1/2gt 1 2 )/t 1 ④ </li></ul><ul><li>In the ② , we can infer that u 2 =(a-1/2 gt 2 2 )/t 2 ⑤ </li></ul><ul><li>Substitute ④,⑤ into the ③,we achieve </li></ul><ul><li>an equation which just has an unkown of g. By caculating , we could get the number of g. </li></ul>

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