PHYSICS 123:  THE COPERNICAN REVOLUTION

LAB EXERCISE 4:  TERRESTRIAL MOTION IN ARISTOTELIAN PHYSICS

 

Materials

      three 100 ml graduated cylinders

      beaker

      funnel

      marbles

      ball bearings

      honey

      oil

      water

      timing device (stopwatch or your pulse)

      ruler

 

In this lab we will investigate Aristotle’s formulation of motion:

V = (constant) F/R,

where V is the velocity of a moving object, F is the motivating force, and R is the resistance of the medium.  We’ll do this by dropping small objects through three different media, of different resistances, and measuring the time of fall.  Our goal is to understand Aristotelian thinking about terrestrial motion in some detail.  It is contrary to the spirit of Aristotle to do quantitative, controlled experiments of this kind, but it will help us, with our modern sensibility, appreciate Aristotle’s ideas.

 

We’ll drop different objects (marbles and ball bearings) into cylinders filled with different media (honey, oil, and water), and measure the time it takes for each object to fall.  You may use a stopwatch to make the time measurements, but you should also try it using your pulse as a timer.  For each experiment you do, record your data and calculations on a separate sheet of paper.

 

1.   Explain how, by measuring the time, you can find the velocity of the falling object.

 

2.   Compare the velocities of two different objects falling through the same medium.  Use these data to characterize the motivating force of the two objects.

 

3.   Compare the velocities of the same object falling through three different media.  Use these data to characterize the resistance of the medium.

 

4.   Repeat step three with a different object.  Do you get the same results for the different media?  Explain your result.

 

5.   Describe the process of the ball bearing falling through honey as Aristotle would have.  What are the elemental compositions of the ball bearing and honey?  What kind of change is it?  What are the four causes of this change? 

 

6.   How does the description of the process from question 5 change if it is a ball bearing falling through water?