Recent content by Pepealej

Homework Statement Inside a very long, straight and hollow plastic tube (R << L) we have ionized liquid moving at a velocity v = 100 m/s. The net charge per unit volume is n = 106 electrons/m3. The radius of the tube is R = 10cm. Around the tube we have a solenoid, with n = 100 loops/m...

And which is the relationship between the size of the holes and the frequency?

Hi! I have a question regarding the Faraday cage. I know how a Faraday cage works and understand the principles that make it work and why (potential difference, flux, gauss' theorem...) but I have a question. Why some Faraday cages work eventhough they have holes in their surface. For...

Hi, my name is Alejandro. I'm a Spanish physics student and I'm in my first year of university here in Spain. Spanish university is of the worst in Europe and I wanted to start again my Physics degree (we call it degree here in Spain, I don't know how it's called in other countries) in another...

I'm recently studying heat transfer processes. I saw that the heat current emited by a radiating body is given by: \frac{dQ}{dt}=H=A e \sigma T^4 I was wondering how to calculate the H from the sun to a unit area here on earth. How should I do it? I've seen exercises where they use this...

Why is the flow through the hole given by:? Q-S\sqrt{2gh} I understand it is the flow that comes in minus the flow that goes out. But when I think of it with the continuity equation, the flow is supposed to be constant. When does the continuity equation apply?

Hi. I was recently calculating some centroids and I was wondering if the point were I choose my origin affects the centroid position. I.e., if I choose my origin at a massive particle, will the centroid be the same as with any other reference frame? Thansk :)

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Hi. I was writing the simplest code ever in Matlab when I got an error using the ezplot function. I wrote this script: syms z t; eq=2600*tan(z)-0.5*9.81*2600^2*(210*cos(z))^(-2)-350; theta=solve(eq, 'Real', true); x=210*cos(theta); y=210*sin(theta)*t-0.5*9.81*t^2...

By the way, the calculaitons I did are correct?

I've rencently been thinking about several systems related to fluid mechanics, and I've asked myself the following question: If I have a cylidrical tank with a small hole in the bottom (the surface area of the hole is small in comparison with that from the tank) and I'm filling the tank with...

Thanks for all the replies. I've understood what all of you meant about the buoyancy force. The weight of the container will increase as the total weight of water displaced by my finger, because the water is exerting a buoyant force on my finger and, by Newton's 2nd law, my finger exerts the...

Hi. I was asking myself the following question. What happens if I have a fluid at rest inside a container, and I introduce my finger in it without applying any force to the walls? Will the weight of the whole system change? My intuition says no (If I don't exert a force on the fluid this...

Ok, now I srart to see things clearly :) I've come up with the value of 42.1 kmps as to being the escape velocity of the solar system from the earth, but I've done so only considering there's a gravitational force: the sun's. I did: 1/2mv-GMsm/distance from Earth to sun=0 But, if I'm...

From a point bellow? Hmmm, good question. Gravity bellow the surface of the Earth is proportional to r, not 1/r^2. Hence I should consider another expression for the potential energy. But, anyway, this is not the case. The expression for the potential energy is unique. :S I'm getting confused.