​Gravity and Resistance

This activity is used to demonstrate the concept of gravity and air resistance to middle school kids and to have a more interactive learning environment where they can make and see their own experiment. The main idea behind a parachute is that they slow down a falling object by creating air resistance or drag. Kids will be given a plastic bag, six pieces of string and also a nut. Construction will consist of cutting the plastic garbage bag into the size of the their desired circular parachute and the end of the six pieces of string will be taped down around the cut out shape evenly spaced out. The nut will be tied to the other end of the string to act as the mass that drags the parachute down to the floor. They then can experiment and see what kind of parachute will give the slowest descent and which ones will reach the ground first.

 

This can be taken a step further and different materials can be used to create the parachute and also different shapes can be experimented with. Different materials can consist of but not be limited to construction paper, tissue paper, newspaper and paper towel. Different shapes can include but not be limited to squares, triangles and diamonds.

 

They then can time the descent of each parachute and graph a time of fall vs. area (A=pi*r^2 for a circle) graph to show that the larger the circular parachute, the slower the fall. The shape of the parachute can also be graphed on a time vs. shape of the parachute graph.

 

Kids should notice that the bigger their circular parachute, the slower the descent. This will lead to the discussion over why the larger and also heavier prachute fell slower than the smaller, lighter parachutes. This can be explained through air resistance. The string opens up the parachute and the parachute acts as a large canopy to increase air resistance as it captures the air inside. Remember from the topic discussion that air resistance is dependent on a couple of things and the size and the shape of the object matters as the increased surface area causes more air molecules to hit the surface of the object. The more air molecules that hit the surface of the object, the greater the air resistance. So in this case, the bigger the parachute, the greater the air resistance and the slower the descent to the ground.

 

In addition, the shape of the parachute also changes the speed at which the parachute hits the floor. Circular parachutes capture air better than any other shape and thus, they fall at the slowest rate. Other shapes like rectangles do not capture the air as well, instead they redirect the air.

 

To make the activity even more exciting, the nut can be traded in for an egg in a basket. Whoever can land the egg safely to the ground without it cracking wins the challenge. Just beware of what a mess this could potentially cause.