# Math Help - Finding constant for gravity problem

1. ## Finding constant for gravity problem

Question:
Find a numerical value for g based on this table using excel. (The function is x = 0.5gt^2 where g represents gravity and t represents time).
Table:
Distance, (x) Time, (s)
0.1 .148
0.2 .196
0.3 .244
0.4 .290

I don’t know how to go about doing this with excel and how I’d estimate the value of g. Maybe taking the ln of both sides or something?

2. Originally Posted by SportfreundeKeaneKent
Question:
Find a numerical value for g based on this table using excel. (The function is x = 0.5gt^2 where g represents gravity and t represents time).
Table:
Distance, (x) Time, (s)
0.1 .148
0.2 .196
0.3 .244
0.4 .290

I don’t know how to go about doing this with excel and how I’d estimate the value of g. Maybe taking the ln of both sides or something?
That would be one way.

You could take the simple way out: Solve the equation for g and calculate it for each data point. Then take the average.

The better way is more along the lines you were thinking of. Calculate $t^2$ from the time for each data point. Then make a graph with $t^2$ as your horizontal axis and distance for your vertical axis. The slope of the resulting best fit line will be equal to 0.5g.

-Dan

3. Originally Posted by SportfreundeKeaneKent
Question:
Find a numerical value for g based on this table using excel. (The function is x = 0.5gt^2 where g represents gravity and t represents time).
Table:
Distance, (x) Time, (s)
0.1 .148
0.2 .196
0.3 .244
0.4 .290

I don’t know how to go about doing this with excel and how I’d estimate the value of g. Maybe taking the ln of both sides or something?
Create a cell to hold the guess for g, then create a new column next to the
time column and put 0.5*r*t^2 in that column, were the t is from the
next cell. NOw you need to form another new coumn with the square of the
difference between the right most and left most column, and sum this new column.

Now adjust the value in g untill the sum is minimised (or use solver to do this for you.

RonL