Wall Definition and 735 Threads

  1. D

    AC to DC Wall Adapter:Vout 12Vdc Measured 19.5V?

    On the adapter, Vout is 12Vdc but when I measured it with a voltmeter it shows 19.5V. Is there a typo or does the voltage somehow drops down to 12V when in use with a load?
  2. K

    Stuck on Physics Assignment: Finding Force Required to Move Block Up Wall

    Hi all, I'm in my first year of university physics (mechanics and waves) and am stuck on an assignment question. The question itself is not complicated, but I feel as though I'm skipping over something important. The question is: A 3.8 kg block is pressed against a vertical wall by a force...
  3. B

    Solving Retaining Wall Problem with No Math/Engineering Knowledge

    I know nothing about math/engineering, so I apologize if this isn't the proper place to post this question. Maybe I should be in a builder's forum or something. :confused: Anyways... I'm building a round retaining wall on a slope at the corner of my house. I'm using stackable bricks that...
  4. K

    Thermodynamics Question heat through a wall

    I'm stuck on this Thermo question dealing with heat transfer through a "plain wall" They give us the area of the transfer A = 1 m^2 They give us the thickness of the wall L = .2 m and they give us the rate of steady state energy transfer rate Qx = .15 kW They then ask, if the temperature...
  5. D

    Calculating Time Length of Train and Wall Intersection

    dont know how else to word the title but here's the problem: you are in a train traveling on a straight and flat track (just assume its going right to left for my explanation) at 3.0 m/s. your window is 0.9 m high by 2.0 m wide and as you look out, the wall is going up at a 12 degree slope...
  6. H

    Find the angle theta at which the ladder leaves the wall

    A uniform ladder of length L leans against a smooth (no friction) wall. The floor is also smooth (no friction) and the ladder makes an angle of Theta-0 with the floor when the ladder is installed at rest. a) Before the ladder leaves the wall, express the equations of motion of the ladder in...
  7. P

    Sliding ladder leaning against wall, and a triangle of maximum area

    Hello, Below are two questions i am unsure of. :rolleyes: Can someone please verify my answers and tell me if i am doing something wrong. thank-you for your help. :smile: 1. A rigid beam 30 m long is leaning against a vertical wall. If the bottom of the beam is pulled horizontally...
  8. S

    Developing a rubbery serpentine wall as a highway median barrier

    I am developing a rubbery serpentine wall as a highway median barrier and I need to know the tensile strength necessary to hold against a 4400 lb pickup moving 62.5 mph. Using an excel spreadsheet and iterations, I subtract the momentum of the wall from that of the pickup at 2 foot intervals...
  9. J

    So, the force on each wall of the box is 138 N.

    A cubic metal box with sides 32.0 cm contains air at a pressure of 1.00 atm and a temperature of 294 K. The box is sealed so that the volume is constant and it is heated to a temperature of 396K. Find the force on each wall of the box due to the increased pressure within the box. [The outside...
  10. N

    Ladder against a wall how simple

    OK, so this appears to be a very simple problem... but I can't seem to find the way to do it... Anyway the problem is: A uniform 6.74 m long ladder of mass 15.6 kg leans against a smooth wall (so the force exerted by the wall, FW, is perpendicular to the wall). The ladder makes an angle =...
  11. U

    Ladder resting against wall - find forces

    A 15m ladder weighing 500N rests against a frictionless wall. The ladder makes a 60 degree angle with the horizontal. I need to find the horizontal and vertical force that the ground exerts on the base of the ladder when an 800N firefighter is 4m from the bottom. the total mg down is 1300N. I...
  12. Math Is Hard

    Soundproofing an Office Wall: A How-To Guide

    The wall behind me in my office is about 10 feet across and about 12 feet high. The top part of it consists of a window panel that is about 10 feet across x 4 feet high. There doesn't seem to be any insulation in the wall and it doesn't block the sound very well (well, almost not at all) coming...
  13. D

    Reach the End of Universe: Is There a Wall?

    If u reach the end of the universe, do u think there's a wall? All thing must have an end right?
  14. N

    What is the purpose of thin-walled cells?

    Cells with thick wall can support the whole organisms. Then what is the function of thin wall?
  15. R

    Mastering Physics: Ball hits wall Elastically

    First off let me say I am completely stumped. I don't remember teacher teaching this, and its definitely not in book(I went through it 3 or 4 times) and its not even the same book mastering physics uses... The Question is : What is the final angle that the ball's velocity vector makes with...
  16. B

    How Much Force Did Jean Valjean Need to Climb the Walls in Les Miserables?

    In Victor Hugo's Les Miserables, the main character Jean Valjean, an escaped prisoner, was noted for his ability to climb up the corner formed by the intersection of two vertical perpendicular walls. Find the minimum force with which he had to push the walls (assume both hands are to exert the...
  17. T

    How Is the Average Force Calculated in an Elastic Collision with a Wall?

    I'm stumped on this question: A ball of mass m moving with velocity v_i strikes a vertical wall. The angle between the ball's initial velocity vector and the wall is theta_i as shown on the diagram. The duration of the collision between the ball and the wall is delta t, and this collision is...
  18. U

    How Does a Wall Push Back with Equal Force?

    If a piece of fabric was stretched out, and I pushed my finger into the fabric with a force of 5N, the fabric will push back the 5N because of its potential energy. correct? So what if I did the the same thing and pushed my finger agaist a wall? The wall doesn't stretch but it still pushs...
  19. E

    A car crashes into a concrete wall

    Here it is: A 2000-kg car traveling at 85.0 km/h crashes into a concrete wall that does not give at all. Estimate the time of the collision, assuming that the center of the car travels halfway to the wall with constant deceleration. (Use 5.75 m for the length of the car.) I know I need to...
  20. I

    What Minimum Force Is Needed to Prevent a Block from Sliding on a Vertical Wall?

    Can someone please help me with this problem? I've tried a few different things but none of them worked... The weight of the block in the drawing is 99.0 N. The coefficient of static friction between the block and the vertical wall is 0.510. (a) What minimum force F is required to prevent...
  21. S

    Solving "6. [SFHS99 5.P.60.]" Physics Problem

    Hey everyone, my first post here, hope it's ok that it's a question... I've got this physics problem that is absolutely stumping me, is abnormal from all the other forces problems I've done before, and uk is throwing me for a loop too...here it is: 6. [SFHS99 5.P.60.] A 5.5 kg block is...
  22. P

    Probablity of Walking through a Wall

    Apparently, if all your particles are primed for tunnelling through a wall then you can walk through it, but the probability of all your particles tunnelling simultaneously is so low that you would have to attempt it more times than the age of the universe in years. Could someone please explain...
  23. kat

    News Hypocrit EU builds Apartheid Wall

    http://worldnetdaily.com/news/printer-friendly.asp?ARTICLE_ID=39998
  24. wolram

    Switch off my PC at the wall socket and reboot

    Help, I have to switch off my PC at the wall socket and reboot to get onto the internet , everything used to work OK. I have, SUSE 9.1, D link router and use Tiscali. Thanks.
  25. Shahil

    News Is the Israel Wall a symbol of oppression?

    http://www.news24.com/News24/World/News/0,,2-10-1462_1560739,00.html What are your views on the wall? My view: It's been nicknamed the "Apartheid Wall" and it dwarfs the Berlin Wall. It's just a massive symbol of oppression which should not exist in todays's society. Why they were allowed...
  26. B

    News Woman raped while Husband chained to wall

    ((P.S: This post is not against American as nation, but it is good idea to hear news from different sources. I think the Video tape of this raping crime exist in the Pentagon after they show it in the Congress)) The US soldier held her by the hair to force her to look at her husband while he...
  27. V

    Should I Consider Momentum or Work Done in Calculating Car Collision Damage?

    I am trying to find the kinematics of a car collision with a wall. To calculate the damages, should I take into account the momentum or work done? In other words, is this proportional to velocity or square of the velocity? Thanks, Venkatesh
  28. P

    Is the Great Wall of China Visible from Space?

    Old news to most of us, but now China is officially recognizing it. http://www.cnn.com/2004/WORLD/asiapcf/03/12/china.great.wall.myth.ap/index.html Have the makers of Trivial Pursuit clued in yet?
  29. N

    What is the magnitue of the average Force from the wall stopping it?

    What am I doing wrong? Question: A 41 g bullet, with horizontal velocity of 496 m/s, stops 13cm within a soid wall. What is the magnitue of the average Force from the wall stopping it? This is how i tried to solve it Vi = 496, Vf=0, and Xf-Xi=.13m So Vf^2=Vi^2+2a(Xf-Xi) Which =...
  30. Monique

    Cell wall and uptake of nutrients

    A cell wall is a rigid structure, so I wonder how organisms with such a structure are able to take up nutrients from their environment? If there is only a plasma membrane, vesicles can be formed which pinch off and thus take up nutrients from the environment and merge with other vesicles to...
  31. A

    Constant force exerted on the ball by the wall?

    a 2.5 kg ball strikes a wall with a velocity of 8.5 m/s to the left. The ball bounces off with a velocity of 7.5 m/s to the right. If the ball is in contact with the wall for .25s, what is the constant force exerted on the ball by the wall?
  32. S

    Tension in the string and the normal force exerted by the wall

    A uniform solid disk of mass M and radius R hangs from a string of length l attached to a smooth wall. We want the tension in the string and the normal force exerted by the wall. | |\ <--- I call this angle A |_\ |__\ |_(..) <--- that's a disk | | So I have it set up so the...
  33. S

    How Far Can a Man Climb a Ladder Before It Slides?

    [SOLVED] Ladder on a wall problem I'm stumped on this problem. I've solved for the distance the person can climb in terms of N(b), but I can't get N(b) in known terms. A ladder of mass 2M and length 2L is kept on a rough horizontal floor and leaned against a rough vertical wall. The...
  34. N

    Pushing a 6kg Pic Against a Wall: Find the Force Needed

    i don't understand this..the way the forces go:frown: if someone could show me how to do it and the steps..that would be great: The static friction coefficient btw a wall and a pic is 0.7 while the kinetic one is 0.3. By what force shoudl one push the 6kg pic against the wall so that it...
  35. H

    Energy of an Infinitely Rigid Object Impacting a Wall

    If you had an infinitely rigid object and threw it against an infinitely rigid wall, where would the energy go?
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