Some to good effect and well thought out, and others, not so much. Have to say, your thought exorcise just got a lot more complicated. But, I do respect and commend your scientific and mathematics knowledge, regardless. I can safely assume you already have. Very interesting, and sometimes disappointing reading.
Great for in a planetary system, but that puts the Alpha Centauri system between 5 and 6 months out. Still fun to watch, though. Save my name, email, and website in this browser for the next time I comment. By using knowledge of basic, Newtonian physics and a calculator, we can find out exactly what that would feel like In our last post, we discussed how the force exerted on an object is a function of its acceleration; if that object is speeding up, slowing down, or changing direction.
How much force can you take? Speeding Up For these calculations, we are going make two assumptions: the pull of gravity from any nearby moon, planet, or star is negligible and there is no friction force in space due to a lack of media such as air or water. Turn, turn, turn Forces are applied when objects accelerate.
Centripetal force pushes you towards the center of turn. Photo credit: Wikipedia Centripetal force requires a slightly different equation because we have to factor account for our X-wing moving in a circle. Previous article. Next article. Would doing this flip-turn be more or less efficient than the very wide turn?
But acceleration is technically any change in the velocity of an object: speeding up, slowing down, and changing direction are all types of acceleration.
That's why, on a rollercoaster, you feel G forces when you round tight bends and are thrown against the side of your seat a change in direction as much as when you plunge from the heights accelerate or grind to a halt decelerate. You feel the thrill, but don't black out, because the coaster's creators designed it to be well within the G-force tolerance of the average person.
The amount of G forces that are tolerable differs by individual. But for all of us it depends on three factors: the direction in which the G forces are felt, the amount of G's involved, and how long those G's last. Roller coasters are precisely calibrated so average people can enjoy the spine-tingling effects of G forces and few of the ill effects.
Depending on which way your body is oriented when it accelerates, you can feel G forces front-to-back, side-to-side, or head-to-toe. Or, in each case, vice versa—for example, toe-to-head. Each of us can tolerate the two horizontal axes a lot better than the vertical, or head-toe, axis. Facing forward in his seat on that final run, Stapp felt front-to-back G forces as he accelerated and back-to-front G forces as he decelerated, and as we've seen, he endured well over 10 times the G's my daughter and I encountered in the glider.
But vertical forces are another matter, and it has everything to do with blood pressure. At sea level, or 1 G, we require 22 millimeters of mercury blood pressure to pump sufficient blood up the foot or so distance from our hearts to our brains.
In 2 G's, we need twice that pressure, in 3 G's, three times, and so on. Most of us would pass out with head-to-toe G forces of just 4 or 5 because our hearts can't summon the necessary pressure. Blood pools in our lower extremities, and our brains fail to get enough oxygen. Fighter pilots can handle greater head-to-toe G forces—up to 8 or 9 G's—and for longer periods by wearing anti-G suits. These specialized outfits use air bladders to constrict the legs and abdomen during high G's to keep blood in the upper body.
Fighter pilots can further increase their G-tolerance by training in centrifuges, which create artificial G's, and by learning specialized breathing and muscle-tensing techniques. All of us, fighter pilots included, can handle only far lower toe-to-head, or negative, G forces. Facing a mere -2 or -3 G's, many of us would lose consciousness as too much blood rushed to our heads. Spinning at high speed, NASA's G research centrifuge at California's Ames Research Center can simulate up to 20 times the normal force of gravity we feel at sea level.
Courtesy NASA. Magnitude and duration are as critical as direction. While John Stapp showed that people can withstand much higher G forces than had long been thought, there is a limit to what anyone can take. It feels sort of like the car is leaning back. This acceleration feels exactly like gravity because both compress that spring between your body parts. And there you have Einstein's Equivalence Principle : an accelerating reference frame is equivalent to a gravitational field.
And here is your answer to the crushing acceleration of the Epstein drive. The acceleration of the spacecraft is just like a super high gravitational field. On the surface of the Earth, the gravitational field pulls mass down 9. So, if you feel 8g's that would be the same as a planet in which you weigh eight times as much on Earth. That means your hand that normally has a weight of 5 Newtons would feel like it's 40 Newtons 1 pound to 8 pounds.
Of course you have to lift more than your hand to turn off an accelerating spacecraft especially when you disable the voice commands. The whole arm might have a normal weight of 35 Newtons 8 pounds such that it would feel like Newtons 64 pounds.
While some people might be able to lift a 64 pound dumbbell, a man that was living on Mars probably couldn't. The gravitational field on the surface of Mars is only 3. But wait! I have one more case to point out how humans feel weight. Let's go back to the two cars on the track. What would happen if I let them accelerate by rolling down an incline? Here's what that would look like. Here both cars are accelerating close to the same value as when I pushed one of them. However, the magnetic spring is not compressed.
OK, that is enough of the description of the scene so that we can talk about physics. The point is that there is one dude "floating" around in the spacecraft during reentry. Before I over-analyze this short scene, let me add a caveat about my philosophy on science and stories. I've talked about this before , so I'll just give a summary: The number one job for a writer of a show is to tell a story. If the writer distorts science in order to make the plot move along—so be it.
However, if the science could be correct without destroying the plot, then obviously I'd prefer it. Obviously this scene has to do with gravity, so we should talk about gravity—right? In short, gravity is a fundamental interaction between objects with mass. Yes, any two objects that have mass will have a gravitational force pulling them together.
The magnitude of this gravitational force depends on the distance between the objects. The further apart the objects get, the weaker the gravitational force. The magnitude of this force also depends on the masses of the two objects. Greater mass means a greater force. As an equation, this would be written as:. In this equation, the masses are described by the variables m 1 and m 2 and the distance between the objects is the variable r. But the most important thing is the constant G —this is the universal gravitational constant and it has a value of 6.
That might seem like it's important, so let me give an example that everyone can relate to. Suppose you are standing somewhere and your friend is right there with you and you two are having a conversation. Since you both have mass, there is a gravitational force pulling the two of you together. Using rough approximations for distance and mass, I get an attractive force of 3 x 10 -7 Newtons.
Just to put that into perspective, this value is fairly close to the force you would feel if you put a grain of salt on your head yes, I have an approximate value for the mass of one grain of salt. So, the gravitational force is super tiny. The only way we ever notice this force is if one of the interacting objects has a super huge mass—something like the mass of the Earth 5.
If you replace your friend with the Earth and put the distance between you and your friend-Earth as the radius of the Earth, then you get a gravitational force of something like Newtons—and that is a force you can feel and you do. Now for the real question. Why do astronauts float around in space unless there is no gravity? It sure seems like there is no gravity in space—it's even referred to as "zero gravity. The short answer is "yes"—there is gravity in space. Look back at the gravitational equation above.
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