- #36
Skhandelwal
- 400
- 3
You told me how it happens...proving by experiments and theories...but i was looking for why.
Technically speaking, the mass of the train matters and you can easily calculate the final speed of the train using the momentum equations. What you will find, however, is that the change in speed is so small you can ignore it. In other words, a person hit by a heavier train will not fly (measurably) further than one hit by a lighter train.Skhandelwal said:I know it is mass times velocity but I can't seem to figure out why a person hit by a train goes farther away than a narrower train in width? I mean on the part that hits the person should matter. Right? If we add another box by the end of train to increase it's weight, I don't how would affect the impact since I don't the vibration will travel down the end the much.
Skhandelwal said:If a bullet goes through a person perfectly, he stands still, but if it bounces off him, he bounces too...why?
Skhandelwal said:I am talking about negligable affect...the bullet does impose that kinda affect...it just isn't great enough to actually bounce the man off. Ex. fighting w/ a sharp sword vs. an iron rod.
Skhandelwal said:You told me how it happens...proving by experiments and theories...but i was looking for why.
Hi Skhandelwal, TVP45 is 100% correct IMO. Essentially you are asking a "why" question. "Why" is generally the purview of priests, not scientists. The scientific method is a method for improving and refining testable predictions (hypotheses) about how the universe behaves. It fundamentally can not determine why the universe behaves that way.TVP45 said:Physics is the way we describe what we measure (and what we expect to measure) in nature. It tells us nothing at all about why nature is the way it is.
Again, the only way to really understand this is to apply math to the problem.Skhandelwal said:If a bullet goes through a person perfectly, he stands still, but if it bounces off him, he bounces too...why?
Velocity is just distance over time in vector form. What exactly happens in a collision depends on the properties of the materials.What is velocity? I understand that w/o velocity, a collision won't take place...but when 2 objects collide, why do they bounce off? Why don't they transform into 1 object speeding up the chemical reaction?
Skhandelwal said:If a bullet goes through a person perfectly, he stands still, but if it bounces off him, he bounces too...why?
What is velocity? I understand that w/o velocity, a collision won't take place...but when 2 objects collide, why do they bounce off? Why don't they transform into 1 object speeding up the chemical reaction?
Skhandelwal said:If a bullet goes through a person perfectly, he stands still, but if it bounces off him, he bounces too...why?
What is velocity? I understand that w/o velocity, a collision won't take place...but when 2 objects collide, why do they bounce off? Why don't they transform into 1 object speeding up the chemical reaction?
Skhandelwal said:5. What is Friction?(what is the cause of the surface being wielded, why isn't it naturally smooth?)
Thx.
kaotak said:I disagree with people saying that physics only addresses the question of "how". I agree that on its most fundamental level, there is no answer to "why". But I think that why everything else behaves the way it does can be explained by citing certain postulates or empirical laws. These postulates or empirical laws are the fundamentals that cannot be explained themselves.
This is a good example. We do not know why momentum is conserved; it could work differently in a different universe. But we do know why the person bounces too, based on our knowledge of the conservation of momentum.
As for your question about friction, I had a similar question. (Skip the first three paragraphs until the boldface.)
kaotak said:The bullet example was misconstrued, but I was addressing elastic collisions in general. It's kind of pedantic to detract from my argument just because of this one example, when it can easily be seen that I could be talking about a tennis ball bouncing off a tennis racket or any other kind of elastic collision.