Today we are going to experiment with GRAVITY! Last week we learned about this mysterious force and tested a few different ways we could defy gravity. If you missed it, check it out here: http://www.discoveryexpresskids.com/blog/defying-gravity
As you know from last week, gravity is the force that pulls all objects towards the core of the Earth. It’s what causes anything that is dropped to fall to the floor, and it’s what keeps you and me from flying off the Earth as it spins on its axis at incredible rates! Every single object is pulled towards the Earth with the same amount of gravity. So in theory, every object should fall at the same speed, right? Let’s test it out.
Grab a rock and a piece of paper. First, drop the rock. Next, drop the paper. Did they both fall at the same pace? Why do you think the paper fell slower than the rock? Next, crumple the paper into a ball and drop it once again. What happened? You should have noticed that the crumpled paper falls faster than a flat piece of paper. What’s going on?
AIR RESISTANCE! The reason that some objects fall slower than others is that they encounter different amounts of air resistance. The amount of air resistance depends largely on the surface area of the object. If the surface area is larger, the air resistance is stronger. That’s why a flat piece of paper falls slower... it has a much larger surface area than a rock. When you crumpled the paper, you reduced the surface area, so it fell faster.
Every object that falls accelerates at approximately 10m/s/s, but at a certain point, that acceleration levels off. That point is called terminal velocity. Terminal velocity is the point at which air resistance balances out the force of gravity. When an object reaches terminal velocity, it quits accelerating and continues to fall at a steady speed.
Your job today is to create a parachute that will allow an egg to float safely to the ground without breaking.
* Tissue paper
Here’s what to do!
1. Design your parachute. Use your imagination! You can use whatever materials you want to design a parachute that you think will help keep your egg safe. Think back to the information you’ve learned. Larger surface area = more air resistance.
2. Once you’ve designed your parachute, start building!
3. Cut four strings of equal length and tape one end to each corner of your parachute.
4. Tape the other end of the four strings to your egg. Make sure to tape them securely so they stick to the egg!
5. Time for testing! Hold your parachute as high above your head as possible, then let it drop.
6. Check your egg! Did it survive? If not, back to the drawing board. Continue redesigning until you have a parachute that transports your egg safely to the ground.
Extension: Create other parachutes of different sizes (make sure to keep all other design aspects the same). Does the size affect how well the parachutes work? Time each parachute to see which one floats the ground fastest/slowest.
Extension: Design other parachutes of the same size but with different materials. Which materials work best? Why do you think this is?