Galileo believed in the law of fall before he began his experiments. These experiments were not proof of the law of parabolic fall, but only served to confirm that the law he believed in was true.

In the laboratory, we shall reconstruct Galileo's experiments with the inclined plane, on which he based the formulation of his law of parabolic fall. The experiments we will conduct in the laboratory are somewhat different from those conducted by Galileo. In our experiment, we will use a smooth, frictionless disk rather than a ball, as did Galileo. In fact, it turns out that Galileo's law of fall does not precisely apply to rolling balls (the roll of the ball itself arises from friction; a sliding ball is similar to a disk).

Moreover, the experiments which we will evaluate in the laboratory are carried out under totally ideal conditions without friction, conditions which do not exist in the real world. Thus the results we received will be totally accurate, unlike the results obtained by Galileo.

Laboratory - THE LAW OF FALL

Interactive Laboratory

First experiment - The motion of the disk along an inclined plane.
Second experiment - The motion of falling bodies.
Third experiment

Experiment one :

In this experiment we will examine the ratio of the distance traveled by the body and the length of the horizontal plane.

Experiment two :

The purpose of the experiment is to learn about the movement of falling bodies. The body located on the inclined plane falls downward, the inclined plane causes its fall to be slower.

As a result of the experiments we have conducted here, we know how long it takes a disk to slide along the horizontal plane over various distances. In the following experiments we will try to learn about the relationship between the distance traversed by the disk and its speed.


Experiment three :

Is there a constant ratio between the time during which the disk is in motion and the distance it travels?

- Will the disk travel double the distance in double the time, or not?

Move to the first experiment with the additions given in the instruction table.

  1. Select the distance for the disk to travel.
  2. Select the double distance.
  3. Select half of the first distance.

Conclusions of the second experiment:

The inclined plane teaches us about the characteristic motion of falling bodies. We know that the force of gravity causes the body to fall along the inclined plane and to fall freely. In principle, there is no difference between falling along an inclined plane and falling freely. The inclined plane only direct the free fall.

Conclusions of the third experiment:

The disk does not travel double the distance in double the time, i.e., the time of motion is not directly proportional to the distance traveled by the body.

In fact, with the help of mathematics, we will be able to use the results of the three experiments in order to find the ratio between distance and duration of motion.

In double the time the disk travels four times the distance. This is a surprising result. At first we thought it would travel double the distance in double the time, but we have seen that this is not so.

In half the time - the disk travels a quarter of the distance.

Following the results obtained we may now investigate whether there is a direct relationship between the distance traveled by the disk and the time required, or if there is a direct relationship between the disk's motion time and the square of the distance. Look at the table: in double the time, the disk travels four times the distance. We know that 2X2=4, i.e., at least in this case, the distance increased with the square of time.


Based on the experiments we conducted, we can conclude that the distance traveled by the disk is directly proportional to the square of time, which is in fact Galileo's law of fall.

Andrea / Mail / Home Page