Croom Physics

Calculations

We are going to calculate the acceleration using the equation a=(2d-vo*t)/(t²)
Click in box D8
Type "="
Type "("
Type "2"
Type "*"
Click on cell B8
Type "-"
Click on cell C5
Type "*":
Click on cell C8
Type ")"
Type "/"
Type "("
Click on cell C8
Type "^"
Type "2"
Type ")"
Type enter

Now we are going to calculate force (F=m*a) in cell E8.
Click on E8
Type "=" (Note: every formula starts with an equals sign)
Click on Cell C4 (Note: Here you are calling the value from cell D8)
Type "*"
Click on cell D8
Type enter

select D8 and E8 and perform an automatic cell fill down to row 17 by clicking in the lower right hand corner of the selected window and dragging selection box down.

At this point you should notice there are some errors.

These errors are caused because when we auto fill, it adjust the cell values in the formula to match the reference location for each row. For example what was called B8 in row 8 would be called B9 in row 9 or B10 in row 10. This is good because it uses the data on the left to calculate the values on the right. But this becomes bad when you have a parked piece of data like the mass and the initial velocity. You have 2 options here. The first is to make another column and repeat the same mass in each row. This looks messy and shouldn't be done for professional work. Option 2 is to make an absolute reference which will make the called value not increment when you auto fill. There are 3 reference styles which are listed below.

$A$1	Both the column and row reference are fixed. Neither will be incremented or changed during a copy or fill operation.
$A1	Only the column reference is fixed. It will not change during a fill or copy, but the row will change.
A$1	Only the row reference is fixed. It will not change during a fill or copy, but the column will change.

The way we are going to do this is as follows

Click on cell D8
In the formula bar change C5 to $C$5
Press Enter

Now auto fill the acceleration calculations again.

Note: The force values changed when you changes the Acceleration column

Click on cell E8
Make C4 Absolute by changing it to $C$4
Press Enter
Auto fill the Force calculations.

Now you want to calculate the average of a row and also calculate percent error. This will allow us to see how to call some built in functions of the program.

Enter into cell A18 "Average="
You may need to adjust the width of column A slightly to make it fit
In B18 type "="
To the left of the formula bar a drop down menu will now appear.
Select Average in this menu.

A box should now appear.
In this box there are 2 cells listed next to "Number1." These cells probably B8:B17. This is read B8 to B17. The average function will then take the average of the numbers between these 2 cells.

Note: if you want to change this range you may type in the cell range or you may click and drag across the cells you want to use to select the cells.

Average Function Cell Change

Make sure you are taking the average of B8:B17 and then press "OK"
Now auto fill B18 to the right getting the average of Time, Acceleration and Force.
Select Cells A18 through E18
Format the cells using the properties, boarder tab and adding a top boarder only.
Select cells A8 to E18
Press the center function in the alignment box of the home tab

Click on cell A18 and bold face the text in this box.
Select cells B18 through E18
Right click and select format cell
Click on the the Number tab
Under categories make sure "number" is selected
Change the decimal places to 1. We need to do this because when we look back at our original distance data, there were some measurements only read to the tenth spot. We need to accurately portray the averages with the correct number of significant figures.

Select cells C2 through C5 and left justify them with the function button in the alignment box of the home tab.

In cell A20 type "Theoretical Acceleration="
In cell A21 type "Experimental Acceleration="
In cell A22 type "Percent Error="

Select Cells A20 through C20
Right click and choose format cell
In the Alignment tab select merge cells
Also in the Alignment tab, under text alignment, choose Horizontal Right (Indent)

Select Cells A21 through C21
Right click and choose format cell
In the Text alignment tab select merge cells
Also in the Alignment tab, under text alignment, choose horizontal right (indent)

Select Cells A22 through C22
Right click and choose format cell
In the Alignment tab select merge cells
Also in the Alignment tab, under text alignment, choose horizontal right (indent)

Type in D20 "9.8" and press enter
In D21 Type "=" then select D18 and press enter

Now we are going to calculate the percent error which is equal to |(theoretical-experimental)/theoretical)|*100%
In D22 type "="
Then from the function drop down bar next to the formula bar select "More Functions..."

In this more function widow you can see that excel has a wide variety of functions ranging from taking the squre root, to suming a set of data, trignotetic functions. The function we want to use now is the absolute value function.
Choose all from the catagory window
Then select ABS and press ok

You could have also searched for the function.

In the function window that now appears type the following "("
Now click D20
Type "-"
Click D21
Type ")"
Type "/"
Click D20
Your fomula should look like the box below.

click ok

The reason we multiply this by 100% is because we want to convert it from a decimal percent into an actual percentage. We don't need to do this in excel because under the format window, we can convert it.