We spoke last year about how gravity *seems* to effect different objects in different ways. In other words, a piece of paper flutters to the ground while marble falls directly to the Earth.

From those conversations we now know that gravity effects all objects on (or near) the Earth in exactly the same way.

However, AIR FRICTION is an entirely different story.

This lab will explore the relationships between physical properties of various objects and the rate they fall.


  • Mass (determined by using a scale)
  • Volume (calculated by measurement, length x width x height)
  • Density (calculated by mass/volume)
  • Surface Area (calculated by length x width)


We know from our last unit that we can determine the rate at which an object falls (especially if we ignore air friction) using the relationship between kinetic energy and potential energy.

A falling object gains kinetic energy and loses potential energy.

By knowing the precise distance an object falls, we can easily calculate how quickly it falls using energy considerations.

We also know that air friction effects different objects in different ways.

Your job in this lab is to determine which physical property effects air friction most profoundly.

1) Make a prediction as to which physical property will effect air friction most profoundly. A practical format is to say something along the lines of:

"The greater the ___________ the (greater or lesser) the air friction."

2a) Design your lab data collection: Your lab design should be fairly simple: Use a ring stand with a motion sensor attached and measure the velocity of various falling objects noting that the max speed will occur just before the object 'crashes' into the catch receptacle.

2b) We will use coffee filters as our 'drop object'. Your job is to add/change/adapt those filters to compare various mass, volume, surface area and densities (for example, an easy way to add mass to your drop object is to simply add filters)

2c) Measuring the thickness of a coffee filter is a bit tricky. We'll use a micrometer to do that... here's how

3) Determine the 'look' of success. The difficult part of this lab involves a more engineering approach to things: Determining before you start what 'success' will look like. In other words, what sort of data will definitively show that one specific physical property influences the effects of air friction the most.

Let's discuss...

Some groups in our last lab had trouble dividing up the work. Some folks took too much initiative, some folks took too little.

4) Run your lab

5) Make adjustments as needed

6) Run it again