Lab#2 Determination of g and some statistics for analyzing data

Purpose
 To examine the validity of the statement: In the absence of all other external forces except gravity, a falling body will accelerate at 9.8 m/s^2.


 Set up
         


    1. Turn the dail hooked up to the electromagnet up a bit;
    2. Hang the wooden cylinder with the metal ring around it on the electromagnet;
    3. Turn on the power on the sparker thing;
    4. Hold down the spark button on the sparker box；
    5. Turn the electromagnet off so that the thing falls;
    6. turn off power to the sparker thing;
    7. Tear off the paper strip and set up the spark paper for the next person to get their data.
    There are a series of dots on the paper corresponding to the position of the falling mass every 1/60th of a second 

Open Microsoft Excel

  1. In cell A1 enter Time; in cell A2 enter 0; in cell A3 enter =A2+1/60  If you highlight ell A3 and several cells below that, the n choose the Edit/Fill/Down menu Excel auto matically fill the cells below with 2/60, 3/60, etc 2.choose a dot to be t=0s dot. Place the 0-cm mark of the 2-meter stick there.  In cell B1 enter Distance; in cell B2 enter 0; in cell B3 enter the positions of the 2th dot from spark tape. Enter the rest of the dot positions in cell B4,B5,etc. 3. In cell C1 enter △x; in cell C2 enter=(B3-B2), Fill down this to the cells below this one. 4. In cell D1 enter Mid-interval time; in cell D2 enter=A2+1/120, then Fill Down. 5. In cell E1 enter Mid-Interval speed; in cell E2 enter=C2(1/60); then Fill Down. 

    Graphing above data

               

                      

                     

Analyzing the class'data for g:

  Open up a mewfile in Microsoft Excel

In cell A1 enter Value of g; in cell Aw through A11, enter class' balues for g frome the spark tape free fall experiment; in cell A12 enter "=average(a2:a11)"; in cell B1 enter "dev from mean"; in cell B2 enter"=a2-$a$12". 

  Highlight the cell B2 through B11. enter the Edit menu select the option Fill Down

  Click on the ells B3 and B4 and see what formula is entered there.I got the form below.

  

     68% confident value of g is in this rang (916 cm/s^2 < g <968 cm/s^2) our experiment has no errors in its assumptions.

    Systematic error：stuff you can blame on a flaw in your assumptions.

    Random error: stuff we can't tie down blame for.