Recent content by Strange design

I would also agree that the magnitude of the velocity, or the speed, is increasing in the negative direction.

Yes, I am just talking about 1-Dimensional motion.

I agree. So look at this graph. I read this to say that the velocity is decreasing from 4.0 s to 14.0 s. Quite frankly, I don't see any other way to interpret it unless you start incorporating speed into the discussion, but that isn't necessary because all of the information about the...

Thanks for the reply. I would also say an object accelerates when it is slowing down or the magnitude of the velocity is decreasing, not just speeding up and increasing, respectively. Its just a negative acceleration. I am not sure i got your response about how you would regard this change...

Thanks for the reply .Scott. So are you saying that either would be fine? To me, if I say that the velocity is "increasing," then by definition, I am saying that he acceleration is positive. In this case the acceleration is negative.

Good afternoon all, For those of you that teach physics, if an object has an initial velocity of - 5m/s and a final velocity of -20 m/s, do you consider the velocity to be increasing or decreasing in this case? I view this to be strictly defined mathematically, that is that the acceleration is...

Thank you so much Bandersnatch! The first two seem most pallatable to me. I will take a look at MOND and TeVes and see what that's all about.

Thank you Bandersnatch! That is exactly what I was looking for. So does that mean we have no real way of measuring these velocities when the galaxy is "face on?" I am intrigued by how these values infer dark matter, and have a hard time accepting that theory rather than some error in...

Can someone point me to a resource that describes, or describe, how the orbital speed of stars within galaxies are observed and measured? I'm struggling with how these values can be attained with any confidence in their accuracy. Thanks :)

Thanks Anorlunda. I think where I am going wrong is that I am attempting to develop a conceptual model for these friction interactions where I am regarding light as a particle, but these interactions may only be able to be modeled with light regarded as a wave.

Ok, so should I rather consider the surface as a mass of oscillators already releasing IR, and then the friction increases the amplitude of the oscillations?

Hello all, I was driving down the road yesterday, and I realized that I don't really have a solid grasp on how frictional forces cause infrared radiation. Can anyone explain, or direct me to a resource that explains, how this happens at the atomic level? I am thinking that the work done...

Thanks for the link. In the answer posted there, the writer calls it the "instantaneous field." What is meant by that?

Thanks for taking the time to explain that. I thought what he was articulating was that because the field is propagating at the speed of light, the time dilation would mean that from the "field's frame of reference" it would arrive instantaneously. I realize that you can't take the frame of...

Well, what I wrote was my paraphrasing of what I interpreted that my professor was saying in lecture. He was posing how relativity explained the "action at a distance," of the gravitational and electrostatic forces. I may have misinterpreted what he said. I certainly didn't mean to suggest...