If you hold an egg between your fingers and then release it, what will occur? Will it float up to the ceiling? Definitely not! It will fall to the ground and most likely crack open. Why? Correct. It is all due to a small force we call gravity.
Thanks to gravity, we have our feet securely on the ground. Without gravity, we might float right into outer space. Instead, Earth pulls us towards its center at all times, keeping us on the ground.
Every object with mass has a gravitational pull on everything surrounding it. That force depends on the masses of the objects. Things with a large amount of mass, such as Earth, exert a strong gravitational pull on the objects near them, such as people and animals.
In addition to pulling other things towards it, Earth also accelerates those objects as they get closer to the ground. In other words, items speed up as they approach Earth. More importantly, the laws of science inform us that all objects—regardless of their mass—gain velocity at the same rate as they fall.
Italian scientist Galileo Galilei calculated the rate at which objects fall. According to his calculations, an object that is dropped falls to the ground at a rate of 9.8 meters per second, squared.
But how can that be? It seems counterintuitive based on our experience with the world around us. For example, if you hold a feather in one hand and a brick in the other and drop them at the same time, they will not hit the ground at the same time. Will they?
Which will hit first? If you said the brick, you are correct! But why is that? If gravity causes objects to fall towards Earth at the same rate, then why will the brick hit the ground long before the feather?
The answer lies in another scientific concept: air resistance. Air is all around us. Those air molecules push against each other and against other objects. They provide an upward force of friction against anything that is falling. Galileo also discovered that the more dense something is, the less it is affected by air resistance. Objects that are less dense will be slowed down more by air resistance.
This explains why a feather will fall to the ground very slowly when dropped. On the other hand, a brick will fall quickly—as if there was no air around it. Scientists who have tested these theories will tell you that, if you drop a feather in a vacuum (a container with no air), it will fall at the same rate as the brick!
Isn’t that fascinating? Think about the last time you dropped something. Was it a piece of paper? A set of keys? A tennis ball? Air resistance would have a different effect on each of these items. Which one do you think would fall the fastest?
Try It Out
We hope today’s feathery Wonder really piqued your interest! If you’re up for more, grab a friend or family member and check out these other enjoyable activities:
- Observe the different rates at which objects fall due to their density and air resistance. Take a feather, a spoon, and various other objects. Create a list of these objects and make predictions about which ones will fall the fastest. Test your predictions by dropping each item from the same height off the edge of a table. Which objects fall the fastest? Were your predictions correct? Did any results surprise you?
- Imagine a world without gravity. Initially, it may seem exciting to float in space whenever you want. However, would it become tiresome over time? How would everyday activities like playing sports, taking a shower, or eating breakfast change? Reflect on these differences and write a short story about life without gravity. How would you adapt? What inventions might be necessary to make life more normal? Enjoy exploring a world without the physical force we often take for granted!
- Feeling up for a challenge? Go online and learn how to replicate Galileo’s experiment to calculate acceleration due to gravity. Make sure you have all the necessary supplies before starting. It’s always a good idea to ask an adult for help. Use your science and math skills to follow Galileo’s steps. It’s truly remarkable that he was able to reach his conclusions using basic materials and simple experiments without modern technology. Would you have liked to be a scientist during Galileo’s time? Why or why not?
Wonder Sources
- http://www.physicsclassroom.com/mmedia/newtlaws/efar.cfm (accessed 12 Sept. 2020)
- https://www.khanacademy.org/science/physics/newton-gravitation/gravity-newtonian/v/would-a-brick-or-feather-fall-faster (accessed 12 Sept. 2020)
- http://www.infoplease.com/cig/science-fair-projects/some-objects-fall-faster-others.html (accessed 12 Sept. 2020)
- http://www.physics4kids.com/files/motion_gravity.html (accessed 12 Sept. 2020)
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