Day 5: Varying perspective

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Date: May 29th, 2018

It is extremely important to be very careful while taking measurements during science experiments. So, today the team explored the possibilities of errors included in the previous trials and ways to avoid them during the experiment. After recording 26 slow-motion videos and analyzing them, we realized how important it is to drop the objects in level with the meter stick.

To prove our hypothesis from yesterday's blog, we marked the floor at certain distances (10 cm, 20 cm & 30 cm) in front of and behind the meter stick, and dropped different balls (golf, steel, lead, wooden and hollow plastic ball) from right above the marks on the floor.  We chose balls of various masses to determine the effect of air resistance on our results.

After analyzing selected videos for these trials, we noticed a pattern: the balls dropped behind the meterstick ended up giving us a lower value of acceleration due to gravity than the accepted value, and the ones dropped in front of the meter stick gave us a higher value of acceleration. These conclusions supported our initial assumptions. And tomorrow, we will continue to analyze the rest of the videos, and then move onto actually typing the instruction and procedure for the experiment.


Figure 1. Snapshot of PASCO Capstone file analyzing the video of the falling golf ball dropped 10 cm in front of the meter stick.

To find the acceleration due to gravity, you will need to plot all the data points marked by the red plus signs on the video on the left in Figure 1. As you see, the slope of the velocity versus time graph is 10.1 m/s with a tolerance of + 0.068 m/s. Since the ball was dropped in front of the meter stick, the acceleration value was higher than the accepted value.




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