If one ignores air friction, the actual acceleration is a constant, 9.8m/s^2.

Now if you are experimenting, and actually trying to measure it, you need a method of plotting distance fell versus time. I have done it with photography in the dark, with a timed light (stroboscope) to give images at selected times.

http://www.edumedia.fr/a217_l2-free-fall-1.html

how do you calculate the acceleration of a free falling object?

To calculate the acceleration of a free-falling object, you can use the following formula:

acceleration = (change in velocity) / (change in time)

In the case of free fall, where air friction is ignored, the acceleration is a constant value of 9.8 m/s^2, also known as the acceleration due to gravity.

To measure the acceleration of a free-falling object experimentally, you can use the method described in the link you provided, using photography and a timed light (stroboscope).

Here's a step-by-step explanation of how you can calculate the acceleration using photography:

1. Set up your experiment: Prepare a setup where you can drop the object vertically, ensuring there are no external forces acting on it other than gravity. Make sure the object's motion can be captured in photographs.

2. Use a timed light (stroboscope): Set up a stroboscope, a device that emits short, intense bursts of light at regular intervals. This will allow you to capture multiple images at different time intervals during the object's fall.

3. Take photographs at regular intervals: Start the stroboscope, and as the object falls, it will pass through the illuminated area multiple times. Use a camera with a fast shutter speed and capture images of the object at regular time intervals. Ensure the camera is positioned properly to capture the object's entire fall.

4. Determine the distance: Measure the distance between the object and the starting position at each time interval. This will give you the distance the object fell during each time interval.

5. Calculate the time intervals: Determine the time between each photograph based on the regular intervals set by the stroboscope. You can use the stroboscope's settings or analyze the timestamp on the images to calculate the time intervals accurately.

6. Calculate the change in velocity: Calculate the change in velocity between each time interval by subtracting the initial velocity from the final velocity. In free fall experiments, the initial velocity is typically zero, and the final velocity at each point is determined by the distance the object fell during that particular interval.

7. Calculate the acceleration: Finally, to calculate the acceleration, divide the change in velocity by the corresponding change in time for each interval. Since the acceleration due to gravity is constant, all the calculated values should be approximately equal to 9.8 m/s^2.

By following this method and using the data obtained from the photographs, you can calculate the acceleration of the free-falling object.