## Experiments with Air Drag and Streamlined Shapes

This aerodynamics experiment explores streamlined vehicles and is a STEM car experiment with an added mix of fine motor skill work. It’s a fun discovery activity for kids! Today’s experiment with streamlined vehicles and shapes was a very fun way to learn about air drag!

## Aerodynamics Experiment

My son loves anything with experiments or discovery, so this STEM (Science, Technology, Engineering, Math) activity was right up his alley.  We discovered why sports cars have pointed fronts and a little about how an object’s shape affects it’s movement with drag and airflow.

## What is air resistance and drag?

In this experiment, we explore air resistance and drag. Both can be visually seen in the car experiment below.

Air resistance refers to the force of air against an object as it moves. In the case of a vehicle, the air has some resistance against the front of the vehicle. Larger vehicles have more physical space pushing against air in front of it as it moves along a road. A smaller, more compact car has less space to resist against the force of air.

Drag is air resistance caused by disturbances in the flow of air over an object.  This force slows down moving objects like the cars in our experiment.

A streamlined shape is one that has less drag, or friction between the surface of the shape and the air resistance as the shape moves through the space. For example, a streamlined shape on a vehicle would have a low and triangular hood (think: race car) as opposed to a boxy rectangular front of a dump truck. The shapes of vehicles are typically designed to be streamlined so that there is less drag from the resistance of air as they move along a road.

## Experimenting with Shapes for Air Drag and Resistance

In this experiment, we are exploring shapes for the resistance they have against the force of air as it moves through space. Streamlined vehicles and boxy, large, or square-shaped vehicles move through air and the space of the road differently. We wanted to take a look at these differences and see how a streamlined car moves.

We used just a few materials for this experiment (I’m including the affiliate links for your convenience.)

You’ll need:

1. Two identical toy cars.  We used ones similar to these.
2. colored cardstock, cut into rectangles
3. stack of books

This is an easy STEM activity to set up.

1. Cut the cardstock into strips that are as wide as the cars.  You’ll want the length to be a little longer than the cars, but even with the end.
2. I taped the edge of the cardstock rectangle to the front of each car, then bent one into a curved shape and the other into an right angle shape.
3. The cardstock is a good material for this experiment because it holds the curve and angled shapes well.  Regular paper will not work as well.
4. Finally, snip the edge of the cardstock so that it ends at the end of each car.

Prediction:  Ask your child their predictions!  What will the shapes do to the cars?  Will one shape go faster? Why?  What will happen when air is applied to the cars?

Now comes the fun part: the streamlined shapes experiment!

Stack a few books and prop one end of the foam board up.  You can use any flat surface for this project, but the foam board was the right length and perfect for both cars to travel without sailing over the edge.

First line each car up on the edge of the foam board.  This is a fun activity in itself; sending toy cars down planks and ramps is a great boredom buster!

Experiment with force, but just tapping the cars down the ramp and pushing.  More force gives them more speed!  We noticed that both cars went down the ramp at the same time.

Be sure to push the cars over the edge of the ramp at exactly the same time.

Next, we applied a source of air to the bottom of the ramp.  Turn on the hair dryer and aim the air toward the cars going down the ramp.  Now, the curved car went faster!

## What is happening in this streamlined shape experiment?

The car with the streamlined shape travels faster because it’s shape disturbs less of the air.  The car with the angular shape disturbs air as it travels.  This un-streamlined shape increases the force called drag and slows the car down.

Have fun with your air flow experiments!  You might also like our Bernoulli’s Principle air glider project: