NEWSFLASH

We interrupt this silence with an important message.

"Contrary to popular belief, the earth's gravitational force exerted on an object in orbit is not zero. Experts estimate that the force of gravity on a satellite such as the International Space Station is actually around 90% of the gravitational force on the station at sea level. How can this be? Stay tuned to find out."

*woman pours spaghetti sauce into a plastic bag*
*bag spills onto floor*
*woman laughs hysterically*
Narrator: "You don't seem to understand the gravity of the situation. This calls for Glad® Food Storage Bags with new extra wide seals."
*woman pours spaghetti sauce into Glad® Food Storage Bag and seals it confidently and happily*
"Now available in local stores."
*woman's son plays football with bag of spaghetti sauce*

"How is it possible that astronauts on the International Space Station are weightless while still experiencing 90% of the earth's sea-level gravitational force?
"Dr. B. I. Ghead of the Northern Alaska University of DRK & CLD explains:

'When a projectile of mass m is launched from the surface of a planet at a launch angle Θ = 0˚ with a gravitational force of G*((Gm1m2)/r²) where G is the gravitational constant, m1 and m2 are the masses of the projectile and the planet, and r is the distance between the center of the planet and the center of the projectile, the initial velocity of the projectile v0 is directly proportional to the range of the projectile. If vo is sufficiently large, the surface of the earth will curve away from the projectile before the projectile can reach the surface. Thus v = √rg is the tangential velocity that will allow the free-fall acceleration to provide the centripetal acceleration (v²/r) necessary for a circular orbit of radius r. This radius r can be found by'

"Wow, pretty amazing isn't it! We'll talk more about this exciting discovery when we come back."

*Sir Isaac Newton walks through orchard*
*birds sing*
*wind blows gently*
*suddenly a bag of Doritos® falls from the tree and knocks him flat*
*Newton sits up*
Newton says breathlessly, "I've discovered gravity... *pant, pant* ... not even our planet can resist Doritos® Spicy Nacho Cheese Tortilla Chips."
*bags fall around him, he lays happily in a pile of Doritos® bags*
Narrator: "Doritos® - Snack Strong"

"Welcome back. We just heard from Dr. B. I. Ghead as he gave us an explanation of gravity in earth orbit. Dave, that was just fascinating wasn't it? *broadcaster Dave nods* I found the part with the m to be especially enlightening; you know, all of us have grown up hearing about m's and n's, but to finally have an explanation of how they relate to the whole universe is really interesting." *Dave nods again* Dave: "I think yours is a universal sentiment. Dr. B. I. Ghead really did a great job in explaining that, um, concept, and I think it is one that could be projected into many other fields - electric and magnetical, excuse me, *laughing* electrical and magnetic fields as well." Lady broadcaster: "Exactly, and I think it's great what Dr. Ghead is doing up in Alaska. He's actually head of their free-fall research class." Dave: "Now from what I understand, correct me if I'm wrong, that class is actually an accelerated class, right? Very intense and fast-moving." Lady: "Actually, I think I heard recently that he's slowing down in his presentation of material because they're reaching the terminal velocity, excuse me, *Dave unintentionally lets out a big snort* the end of the term up there in Alaska." Dave: "Well, those term ends come pretty fast that far north since their days are so much shorter. I've heard that an Alaskan day is 30% shorter than a typical day. Lady: "Really! I'm learning all sorts of interesting things today. We'll be right back with updates on the absence of weather in the Midwest."




Ok, all that to say, I finally figured out why astronauts are weightless even when there is gravity in orbit. They are in constant free fall!
It's so simple, it makes me feel dumb. Basically, when a projectile is launched fast enough, the earth's surface curves away from the projectile before it can hit the ground. So, the International Space Station is constantly falling towards the earth's surface which is why the astronauts (and the station) are weightless.

It was a big realization for me one day in physics class, and it warranted breaking the silence of a dormant blog.

As for the sick humor, hey, it's late, it's almost spring break, I got my physics test over with today, so you'll just have to put up with my craziness.