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maniactickler said:Not sure about that type of wind. my specialty is in the field of breaking wind.
Things get a little weird when you get close to the speed of light. As an object with non-zero mass approaches the speed of light, relativistic effects cause its mass to increase, which means you would need an ever increasing amount of force to achieve the same acceleration. The effect is that a object of non-zero mass would require infinite energy to reach the speed of light.Goodieluver said:
That's what you get for asking a physics professor something. The answer you get is likely to be technically accurate, but may assume or take for granted factors that you aren't informed of. Or the scientist may have needed information that you didn't know he needed in order to give you the answer you were actually seeking.Goodieluver said:
Theoretically, no. As Icycle noted, an object's mass increases as it accelerates. At most speeds humans deal with, this effect is so small that it's almost unmeasurable. But as you approach the speed of light it becomes very significant. Looking at the equation above you can see that a larger mass requires a larger force to maintain the same acceleration. As velocity approaches the speed of light, the object's mass approaches infinity, and therefore the force required to keep it accelerating likewise approaches infinity.
Redmage said:That's what you get for asking a physics professor something. The answer you get is likely to be technically accurate, but may assume or take for granted factors that you aren't informed of. Or the scientist may have needed information that you didn't know he needed in order to give you the answer you were actually seeking.
Very literal-minded creatures, scientists.
What the professor told you is true as far as it goes. Acceleration is dependent on two things: the NET forces acting on an object (such as thrust, gravity, and friction), and the MASS of the object. In mathematical terms,
Acceleration = Force/Mass
Theoretically, no. As Icycle noted, an object's mass increases as it accelerates. At most speeds humans deal with, this effect is so small that it's almost unmeasurable. But as you approach the speed of light it becomes very significant. Looking at the equation above you can see that a larger mass requires a larger force to maintain the same acceleration. As velocity approaches the speed of light, the object's mass approaches infinity, and therefore the force required to keep it accelerating likewise approaches infinity.
This is why it's not even theoretically possible for any object with mass to reach the speed of light.
But there are other problems with the solar sail. First, you never have a situation in which there are no outside forces acting on an object. Even in the vacuum of space gravity is a consideration. The solar wind pushes objects away from the sun, but the sun's gravity pulls them back, reducing the net acceleration available. In addition, the solar wind itself becomes weaker and weaker as you move away from the sun. If you double your distance from the sun the force of the solar wind is reduced to 1/4 of what it was originally. This means less and less accelerating force as you move out from the earth's orbit.
Solar sails aren't completely useless. Their big advantage is that they allow a spacecraft to be built with no mass (or very little mass) wasted on propulsion systems: fuel, rocket engines, and all the infrastructure needed to feed the one to the other. If you look at the tiny payloads perched atop huge rocket boosters in the space program, you can see that this is no small thing. But they probably won't be the answer to interstellar flight.
Einstein's Theory of Relativity. The faster an object goes, the more massive it becomes. The more mass it has, the more energy is required to accelerate it at the same rate. Even in a perfect vacuum with no other gravitational forces, your theoretical accelerating mass could never reach the speed of light.Goodieluver said:
Um, OK. It looked as though you said they told you that "acceleration is dependant on the force exerted and the force thats resisting." That's what you wrote, anyway. Is that not what you meant?Goodieluver said:
And Icycle and I answered that question:
Don't worry about it. There's nothing wrong with ending a sentence with a preposition. For example, which of these sentences sounds correct to you?isabeau said:
Icycle said:
