Galileo reasoned that all objects should fall with the same uniform acceleration independent of their mass. It is said that Galileo conducted experiments from the leaning tower of Pisa to verify this hypothesis, but this is not likely to be true. The hypothesis that objects should fall with uniform acceleration was not one that could be easily verified at the time, due to the limited nature of timekeeping devices. In fact Galileo verified his hypothesis indirectly by examining the motion of balls rolling down inclines – a method that was less glamorous but more effective.

In this lab we will attempt to verify the hypothesis directly by dropping snow balls and timing their fall using stopwatches.

When a body falls from rest through a distance d in time t the relationship between the variables d and t depends on the nature of the motion. If the motion is uniformly accelerated motion then the following relationship holds

d = ½ g t².

The purpose of this lab is to verify the above relationship using graphical analysis and to determine an experimental value of the acceleration due to gravity g.

First drop snow balls with a variety of different masses from one storey up to verify that the motion is independent of mass. Is it?

Now drop a suitably medium sized snow balls from a good range of different heights and use a stopwatch to time their fall. Repeat the measurement several times at each height.

Using your data plot a graph of t² vs. d (t is the dependent variable in this experiment and hence should go on the y-axis). If the motion is uniformly accelerated the resulting graph should be linear. Use Excel to find a linear fit for the data and hence find the slope of the line. Relate the slope of the line to the acceleration due to gravity g. Compare your result with the accepted value for g=9.81 m/s²