Recent content by lavalamp

Thank-you gabbagabbahey, that helped my understanding a lot. Additionally, I didn't spot it at all, but now that you've pointed out that it's basically the product rule, it's like I can't unsee it. :smile:

I'm not quite sure I know what you mean, but to expand a little on how the integration proceeded in my first post: \vec{F} = y\hat{x} + x\hat{y} d\vec{s} = \hat{x}dx + \hat{y}dy \int \vec{F} \bullet d\vec{s} = \int (y\hat{x} + x\hat{y})\bullet(\hat{x}dx + \hat{y}dy) \int \vec{F}...

So I have this vector Force: \vec{F} = y\hat{x} + x\hat{y} This force is conservative (\nabla \times \vec{F} = 0). So I integrate it to find the potential energy: U = -\int \vec{F} \bullet d\vec{s} U = -\int y \delta x - \int x \delta y U = -yx - xy U = -2xy Ignoring the...

Indeed, I understand that a thin coating of paint, even if it had very low thermal conductivity, would be a decidedly sup-par insulator. That is why I decided to focus most of my attention on its emissivity. I'm not going to measure emissivity too far into the UV, as I said perhaps to about...

Homework Statement I have a university project that involves comparing various paints with regards to how they affect the insulating properties of houses. As part of that I would like to measure the emissivity of the paint for a variety of wavelengths. Unfortunately I can not simply heat...

Thanks for the reply. Yeah, for the integration in the first one I had a bad feeling about that as I was doing it, but I didn't, and don't, know what else to do there. Do you have any suggestions about how I can um ... not do it wrong? I'm pretty much at the limit of what I know here, which...

Homework Statement Hey all, this isn't actually a homework question, but I guess it's of that type. For some time now I've had this (not entirely realistic) mechanics problem that I keep leaving for a while, and then coming back to. Basically, I'm not getting anywhere so I am asking for some...

You just need to caclculate the pressure difference between the inside and the outside. It's just like if you wanted to calculate the next force acting on a body if it had 4N acting on it one way, and 10N acting on it the opposite way. The net force is 6N, in the direction of the biggest...

Well, if you were finding the pressure difference, you'd need to subtract, not add. However it's not as simple as that since the internal area and external area of the building are not the same due to the thickness of the walls. It sounds like this building is a cylinder, but you've taken the...

You need to know the area of the hatch. I had a quick look round but couldn't find it anywhere. If you wanted to make a rough guess you could assume perhaps 0.25 m^2 and go from there. You need to use the formula: Pressure = Force * Area

Since you are assuming that resistive force is directly proportional to velocity, you know: F \propto v F = kv Therefore: P = Fv P = kv^{2} You now need to find the constant k, then you'll be all set.

Looks like this was moved to homework help, but rmarkatos had already posted there. May be best to continue in the other thread.

Calculate the maximum vertical displacement of the ball, from that you can calculate the maximum gravitational potential energy, when it's kinetic energy is zero. When the system comes to rest, it will have no kinetic energy and it will be at it's minimum gravitational potential energy...

No problem. The thing to realize is, you had the value for the power / m^2 at whatever arbitrary distance from the plane, then 3/4 of the engines were shut down, so you automatically know the new power / m^2 at this arbitrary distance.

OK, you have the value for I, divide by four and calculate the new sound level intensity.