If humans could fly, without tools and machines, how fast do you think we would go? As of 2012, the world record for fastest short-distance sprint speed is roughly 27 miles per hour. Running speed depends on how much force is exerted by the runner's legs, and according to Newton's Second Law of Motion, force is the product of mass times acceleration. And Newton's Third Law states that for every action, there is an equal and opposite reaction. So, that means running requires having a ground to push off from, and the ground pushes back against the runner's foot. So, flying would actually be more similar to swimming. Michael Phelps is currently the fastest human in water and the most decorated Olympian of all time. Guess how fast he swims? The answer may surprise you. His fastest recorded speed is less than 5 miles per hour. A child on the ground can easily outrun Michael Phelps in water, but why is that? Well, let's go back to Newton's Third Law of Motion. When we run, we move forward by pushing against the ground with our feet and the ground pushes back, propelling us forward. The ground is solid. By definition, it means the particles are essentially locked into place and must push back instead of getting out of the way, but water is liquid and flows easily. When we move our limbs to push back against the water, a part of the water molecules can just slide past one another instead of pushing back. Now, let's think about flying. Air has a lot more free space for particles to move past one another, so even more of our energy would be wasted. We would need to push a lot of air backwards in order to move forward. Astronauts move around in shuttles in zero gravity when they're in outer space by pulling on handles installed on the ceiling walls and floors of the shuttle. Now, imagine you were given the ability to float. How would you move around in the middle of the street? Well, you wouldn't get very far by swimming in air, would you? Nah, I don't think so! Now, assuming you were granted the ability to float and the speed to move around efficiently, let's discuss the height of your flight. According to the Ideal Gas Law, P-V N-R-T, pressure and temperature has a positive correlation, meaning they increase and decrease together. This is because the air expands in volume with less pressure, so the molecules have more room to wander around without colliding into each other and creating heat. Since the atmospheric pressure is a lot lower in high altitudes, it would be freezing cold if you were flying above the clouds. You'd need to wrap yourself up to keep your core body temperature above 95 degrees Fahrenheit, otherwise you'd start shivering violently, gradually becoming mentally confused and eventually drop out of the sky due to loss of muscle control from hypothermia! Now, the Ideal Gas Law implies that as the pressure decreases, gas volume increases. So, if you were to fly straight up too quickly, the inert gas in your body would rapidly expand the way soda fizzes up when shaken. The phenomenon is called "the bends," decompression sickness, or "divers disease" since deep sea scuba divers experience this when they come up too quickly. This results in pain, paralysis, or death, depending on how foamy your blood becomes. Okay, well, let's say you want to fly just a few meters above the ground where you can still see the road signs and breath oxygen with ease. You'll still need goggles and a helmet to protect you from birds, insects, street signs, electrical wires, and other flying humans, including flying cops ready to hand you a ticket if you don't follow the flying rules, buddy. Now remember, if you have a collision mid-air that knocks you unconscious, you would experience free fall until you hit the ground. Without society or the laws of physics, flying would be a totally awesome ability to have. But, even if we could all just float around a few feet above the ground and only moving at a snail's pace, I'm telling you, it's still a cool ability that I'd want, wouldn't you? Yeah, I thought so. Now, which superpower physics lesson will you explore next? Shifting body size and content, super speed, flight, super strength, immortality, and invisibility.
Jika manusia bisa terbang, tanpa alat dan mesin, akan seberapa cepatkah kita? Tahun 2012, rekor dunia untuk lari pendek tercepat adalah sekitar 27 mil per jam. Kecepatan berlari bergantung pada gaya yang dikerahkan kaki pelari, dan bergantung pada Hukum II Newton, gaya adalah hasil dari massa dikali percepatan. Dan Hukum III Newton menyatakan untuk setiap aksi, selalu ada reaksi yang sama besar dan berlawanan arah. Artinya, dalam berlari kita membutuhkan landasan untuk bertolak, dan landasan akan mendorong kaki pelari. Jadi, terbang sebenarnya lebih mirip berenang. Michael Phelps adalah manusia tercepat dalam air saat ini. dan juara olimpiade paling berprestasi sepanjang sejarah. Tebak seberapa cepat ia berenang? Jawabannya mungkin mengejutkan Anda. Rekor tercepatnya adalah kurang dari 5 mil per jam. Seorang anak bisa berlari lebih cepat di daratan mendahului Michael Phelps, tapi, mengapa? Mari kembali ke Hukum III Newton. Saat berlari, kita bergerak maju dengan bertolak pada tanah menggunakan kaki dan tanah akan mendorong balik melempar kita ke depan. Tanah itu padat. Secara definisi, artinya semua partikel terkunci pada satu tempat dan harus mendorong balik, bukan tersebar, tapi air adalah benda cair dan mudah bergerak. Ketika kita bergerak untuk bertolak di dalam air, sebagian molekul air meluncur di antara satu sama lain dan tidak mendorong balik. Sekarang, mengenai terbang. Udara memiliki banyak ruang bebas tempat partikel bergerak, jadi kita justru lebih banyak membuang energi. Kita harus mendorong udara ke belakang untuk bisa maju. Astronot bergerak di pesawat di gravitasi nol ketika di luar angkasa dengan berpegangan pada besi yang dipasang di langit-langit dan di lantai pesawat. Bayangkan Anda punya kemampuan untuk melayang. Bagaimana Anda akan bergerak di tengah kota? Tidak bisa jauh-jauh kalau hanya berenang di udara, kan? Tentu tidak! Jika Anda punya kemampuan untuk melayang dengan pergerakan yang efisien, mari diskusikan mengenai tinggi penerbangan Anda. Menurut hukum gas ideal P-V N-R-T, Tekanan dan temperatur mempunyai hubungan positif, artinya, mereka meningkat dan menurun bersama. Ini karena volume udara memuai dengan tekanan yang kecil, jadi molekul punya ruang untuk berkeliaran tanpa bertabrakan antara satu sama lain dan menghasilkan panas. Karena tekanan atmosfer lebih rendah di ketinggian tinggi, rasanya dingin membeku jika terbang di atas awan. Anda harus berpakaian tebal untuk menjaga temperatur tubuh di atas 35 derajat celcius. Kalau tidak, Anda akan menggigil menjadi kebingungan perlahan dan akhirnya jatuh dari langit karena otot jadi lemah akibat hipotermia. Hukum gas ideal menyatakan ketika tekanan turun, volume gas akan naik. Kalau Anda terbang lurus ke atas terlalu cepat, gas lembam di dalam tubuh Anda akan memuai dengan cepat seperti soda yang habis dikocok. Fenomena ini disebut “bungkuk,” sindrom dekompresi, atau “penyakit para penyelam” Karena penyelan scuba mengalami ini kalau mereka terlalu cepat naik. Ini mengakibatkan kesakitan, kelumpuhan, bahkan kematian, bergantung pada seberapa berbusa darah anda. Oke, misal Anda ingin terbang hanya beberapa meter di atas tanah, Anda masih bisa melihat tanda jalan dan bernapas dengan mudah. Anda akan perlu kacamata dan helm untuk berlindung dari burung, serangga, tanda jalan, kabel listrik, dan penerbang lainnya, termasuk polisi terbang yang siap memberi sanksi kalau Anda tidak menaati peraturan, Kawan. Ingat, kalau bertabrakan di udara sampai tak sadarkan diri, Anda akan terjun bebas sampai tanah. Tanpa aturan dan hukum fisika, terbang bisa menjadi kemampuan luar biasa. Tapi, bahkan kalau hanya melayang beberapa kaki dan bergerak lamban, itu sudah cukup keren dan saya menginginkannya, bagaimana dengan Anda? Ya, sudah kuduga. Setelah ini, pelajaran kekuatan super apa yang akan kau pelajari selanjutnya? Mengubah ukuran dan isi tubuh, kecepatan super, terbang, kekuatan super, keabadian, dan menghilang.