INCREASING MASS

• 1. If you have visited the other pages within this web site, then you know that when an object approaches the speed of light it gains more and more mass as more and more energy is applied. But how is this so? How does an object just gain mass? This effect is really simple and you experience it every time you ride a roller coaster, ride in a speeding car, or any other means of transportation. I am sure once I explain it, you will have a very good idea of how this trick is done.
• 2. Here, on our planet, the amount of downward force gravity exerts on any object is call 1 g. Without this g force we would float around on the planets surface and the slightest bump or push could send you floating off into the stratosphere. But our 1 g of gravity saves us for such a fate. In this 1 g gravitational field lets say we conducted an experiment with a volunteer we will call "Bob". Her on Earth we know Bob weighs 150 pounds. On the moon Bob would weigh only 25 pounds. This is because the moon has 1/6th of the Earth's gravity. Bob has the same mass as he did on Earth, but because he is in a weaker gravitational he has less weight.
• 3. Before I go any further, I would be remised if I didn’t explain the difference between mass and volume. The amount of mass and object has is a measure of it's resistance to acceleration. And an objects volume is simply the amount of space the object occupies. If you had two spheres, sphere A in made of lead, and sphere B is made of plastic. In addition to this, sphere B it twice the size (volume) of sphere A. Now lets say you push sphere B with just enough force to get it to slow roll. If you push sphere A with the same amount of force as you used on sphere B, sphere A will not move. Sphere a takes more force to move because although it has less volume than sphere B, it has more mass.
• 4. If Bob were on a spaceship that was at rest and was removed from any gravitational field, he would float around inside the space ship. He would have no since of up are down. No matter how Bob positioned himself in the spaceship he would feel no since of being pulled in any way and he would weigh nothing. If Bob guts out his trusty weight scale and try to stand on it, he would find he has no weight. If he decided you wanted to travel to a nearby planet, Bob would need a push in that planets direction. Normally this push is the thrust of a rocket engine of some sort or another. Once the rocket begins to move, it would literally move around Bob until he hit the wall in to opposite direction of travel. Sir Isaac Newton's first law of motion states any object at rest tends to stay at rest until acted upon by another force and any object in motion tends to stay in motion until acted upon by another force. Thus once our hearty subject touches a wall of the spaceship, he would begin to move with the ship. Now Bob will feel like the wall he is touching is in the direction of what we can call "down. He now feels like he in standing on the floor and he has weight. If he pulls out his scale again and stood on it, he you find that he now has weight. If the spaceship is accelerating at 1/2 a g, Body you find he weighs 75 pounds. At 2 g's He would weigh 300 pounds. Once again, how is Bob changing his mass. Stop the spaceship's acceleration at 2 g's and Bob will soon return to his weightless state. Einstein proved this in his Theory of Special Relativity. Once again, Bob is in a 0 g state. Now lets say our fateful space traveler wants to get to his planet quickly. He may be inclined to start his rocket's engine once more and accelerate at 1 g. The force of 1 g is 32 feet per second per second. This means to travel at 1 g Bob would need to travel 32 feet in the first second, 64 feet in next, 96 feet per second in the second after that and so on and so forth. In every consecutive second he would have to travel 32 feet further than he did in the last. For a 2 g acceleration Bob has to travel at 64 feet per second per second. At 3 g's 96 and so on. Bob is rocketing along a 1 g. Once again he feels a gravitational field on his spaceship. If he were to pull out his scale again, he would find he is getting heavier and heavier. This is because with every second that passes his ship is moving faster and faster, so his body is resisting this moving more and more. It is like riding on an elevator. When you step into an elevator that is at rest, you feel on 1 g of force on you body. But once the elevator start going up you feel as though you are being pulled down a little more and you keep feeling this extra pull until the elevator reaches it's top speed. This is because your body, like Bob's, is resisting being accelerated or moved. Once the elevator begins to slow it upward climb, you feel you are being pull down a little less now because as the elevator motor runs slower the elevator slows down. You on the other hand keep moving up at the same speed until gravity slows you down. If you were standing on a scale, in the elevator when it started to move up, you would find you weighed more and more as the elevator accelerating. When the elevator reached it's top speed, you would see your weight stabilize and remain at the weight. When the elevator starts to slow down you will find you weighed less than when you first stepped into the elevator. These are the forces Bob is experiencing. His spaceship is also going though the same processes. This is the reason why we can’t reach he speed of light. At 99.999 the percent of the speed of light, Bob would weigh 17 1/2 tons! And as for his spaceship, if it weighs 100 tons when at rest it would weigh 23,333 tons at 99.999 percent the speed of light. Clearly his ship cannot accelerate this amount of mass to the speed of light. Once Bob's spaceship reached it's top speed of, lets say 10 percent to speed or light, he would need a more powerful engine if he wanted to go faster. If he could magical have a engine twice as powerful as the first appear in his ship and start running, he would speed up, but this new engine would soon run into the same problem as the last. Bob' weight and the ship's weight would increase as the ship sped up until once again the acceleration stopped.
• 5. Now lets suppose Bob's ship used 100,000 tons of thrust to accelerate to 30 percent the speed of light. If he added another 100,000 tons of thrust his speed would not double as you might expect but only increase by a few percent. This effect gets worse and worse as his speed increases. If he was traveling at 99 percent the speed of light and he added 100,000 of thrust to his engine he would notice no increase in speed. Clearly this is a problem the will take many year and many very intelligent physicist to concur.
  BACK TO MAIN PAGE