Wall Definition and 735 Threads

A ball is spun in a vertical circle on a string. A light is shining from the side of the circle so that a shadow of the balls motion is shown on a wall behind it. The shadow is simply a circle moving up and down in a straight line (I can't attach the image). The amplitude of the shadow is 0.5m...

HIGH (800C+) wall temperature measurements - experimental help! Hi All - I'm seeking some advice from any experimentalist types. I'm working on a project analyzing heat transfer properties of exotic fluids. We have a simple experimental setup: laminar flow in a small diameter stainless steel...

Homework Statement An electron is trapped in a 1D potential described by: V(x) = 0 if x < R0 V(x) = infinity if x > R0 Electron is in lowest energy state, and experiment shows that: (\Delta)x = sqrt(<x2> - <x>2) = 0.181 x 10-10 Show that <x> = 0.5R0 Homework Equations...

Problem: A race car skidding out of control manages to slow down to 90km/h before crashing head-on into a brick wall. Fortunately, the driver is wearing a safety harness. Using reasonable values for the mass of the driver and the stopping distance, estimate the average force exerted on the...

Homework Statement I am trying to find the temperature profile through a cylinder wall. It is a one dimensional, steady state conduction problem without internal heat generation Homework Equations d/dr(r*dT/dr)=0 where r is radius and T is temperature The Attempt at a Solution I...

Homework Statement 4.80×10^23 nitrogen molecules collide with a 16.0 cm^2 wall each second. Assume that the molecules all travel with a speed of 410 m/s and strike the wall head on. Answer in pascals Homework Equations P=mv/A The Attempt at a Solution Ordinarily I would use...

Homework Statement A 261 g hockey puck is sliding on ice with a speed of 5.34 m/s hits a wall at an angle of 27.3° to the wall and bounces back at the same angle with the same speed. a) If the wall and the hockey puck are in contact for 10.9 ms, find the magnitude of the impulse on the...

Homework Statement A 259 g hockey puck is sliding on ice with a speed of 5.34 m/s hits a wall at an angle of 34.8° to the wall and bounces back at the same angle with the same speed. If the wall and the hockey puck are in contact for 11.3 ms, find the magnitude of the impulse on the puck...

Homework Statement The scale on a map is 1:25000. The length of a wall on the map is 3.2 mm. Find the actual length in metres.Homework Equations The Attempt at a Solution

Hey everyone! Got an interesting problem here, I am thinking I did it correctly but I wanted to see your opinions. Here is the problem.. A 0.2-m-thick plane wall is constructed of concrete. At steady state, the energy transfer by conduction through the wall is 0.15 kW/m2. The inside...

Homework Statement The owner of a small restaurant needs to move a table in order to have space for a new display. Ordinarily, a lamp of mass m is hanging over the table, suspended from a string attached to the ceiling. With the table in a new position, the lamp needs to be moved. To this end...

For my research I am going to be testing a swept wing in a wind tunnel. Currently I am looking into tunnel wall corrections and I was wondering if anyone knows of somewhere I can get uncorrected and corrected experimental data on a swept wing in a wind tunnel so that I can test out the...

Homework Statement A hockey-disk with mass m, radius "r" collides with a wall in an angle "alpha" with velocity "v". There is friction, but the place where the ball touches the wall doesn't slide. How does the velocity component that is parallel to the wall change? The collision is completely...

Homework Statement Calculate wall loss rate in BTUs per hour. For a 10 ft by 10 ft room with an 8 ft ceiling, with all surfaces insulated to R19 as recommended by the U.S. Department of Energy, with inside temperature 68°F and outside temperature 28°F: heat loss = \frac{Q}{t} = \frac{(Area)...

Homework Statement Two light sources half a millimetre apart with a wavelength of 550nm shine on a wall exactly 50cm away. What is the distance between the centre point on the wall and the 10th bright spot out? Homework Equations x=nLv/d The Attempt at a Solution...

Homework Statement To measure the static friction coefficient between a 1.64-kg block and a vertical wall, the setup shown in the drawing below is used. (The dots are only there because spaces didn't work) ......| ......|W SPRING----->(Block)|A ......|L ......|L ......| A spring (spring...

Hi - I'm just starting to build a few basic circuits and am looking to get easy access to a low voltage ac power supply. I pulled apart a power brick, and it only has 4 diodes, a cap, and a transformer. If I pull out the cap and the diodes and solder the cord to the leads on the transformer, I...

Homework Statement How thick a concrete wall would be needed to give the same insulating value as 3.5 inches of fiberglass? Homework Equations Q = -A·k·ΔT/Δx k = -Q·Δx/A·ΔT The Attempt at a Solution So here, k is equal to the insulating value, and since I want the insulating value...

For what it's worth, I came up with this problem, so perhaps it cannot be solved, or there could be a way to solve it without using all of the information given. Homework Statement A chair rests on a weighing scale and a wall. The relevant surfaces of the scale and the wall are...

Homework Statement a ball w/ mass of .15kg and a velocity of 5m/s strikes a wall and bounces right back with v=3m/s. ball is in contact with wall for 0.1 sec, how much force did the wall exert on the ball? Homework Equations Ft=mvf-mvi F=? t=0.1 m=.15 vf=3m/s vi=5 The Attempt at...

Homework Statement I HAVE PROBLEM and please help me the question is : how can I draw free diagram mass on the wall mass : 12kg fa : 45 angle 30 Kinetic coefficient of friction:0.25 find net f Homework Equations l can not draw the free diagram fx=0 fy=ma l don't sure l used...

Homework Statement A 0.1 kg rubber ball and a 0.1 kg clay ball are both thrown at the wall with the same initial velocity. the rubber ball bounces, the clay ball sticks. Which exerts a larger impulse on the wall?

Homework Statement You are trying to quickly make breakfast for school. You plug a cofee maker which uses 1200 W into a plug and then plug a toaster of 1800 W into the same electrical outlet. Will the circuit be able to make the load if the circuit breaker is rated 15 A? W1 = 1200 W W2 =...

NOTICE: THIS IS NOT AN ACTUAL HOMEWORK PROBLEM. Homework Statement A projectile is launched from a hill 2m high 8m away from the base of a slanted wall at a velocity v at an angle of 35 degrees from the horizontal. The equation of the slanted wall is y = 2.8x. The slanted wall is 20m high...

Homework Statement This is a two part problem I figured out the 2nd part but not the first. a) A 7.3 m ladder whose weight is 364 N is placed against a smooth vertical wall. A person whose weight is 810 N stands on the ladder a distance 2.7 m up the ladder. The foot of the ladder rests on...

In a period of 1.1 s, 5.0 x 10^23 nitrogen molecules strike a wall of area 9.0 cm^2 . If the molecules move at 260 m/s and strike the wall head on in a perfectly elastic collision, find the pressure exerted on the wall. (The mass of one N2 molecule is 4.68 10-26 kg.) Molar mass=mass of...

Homework Statement The person in figure 8.31 weighs 800 N. the forces F1 and F2 have magnitudes of 100 N and 900 N respective. Assume the force of gravity acts downward through point A as shown. Determine the net torque on the person about axes through points A, B, and C perpendicular to the...

Homework Statement A 1.0 kg wood block is pressed against a vertical wood wall by a 12 N force (into the wall, at a 30 degrees angle up from the horizontal). if the block is initially at rest, will it move upward, move downward, or stay at rest? The attempt at a solution ive written...

I'm having trouble with understanding how to calculate a wall thickness change in a hollow cylinder unde axial loading. The length, outside diameter and initial wall thickness are given as well as the size of the load, Young's modulus and Poisson's ratio. I guess this isn't really a hard...

My teacher just explained to us Newton's Third Law, and one example she used was her pushing against a wall. She stated that the net force would equal zero because the wall was pushing back, but that doesn't make sense to me... What I was thinking was that the force of her pushing was weaker...

I was given a problem based on statics and I was wondering if anyone could help. A window washer attempts to lean a ladder against a frictionless wall. He finds that the ladder slips on the ground when it is placed at an angle of less than 75◦ to the ground but remains in place when the angle...

Homework Statement Weight of sphere = W and a force P is applied on its surface to attain equilibrium (Friction is present). Then 1. Pmin = √3W/2 2. Pmin = (√5-1)W/2 3. When P is minimum, Angle of friction max between sphere and wall is cos-1 (√5-1)/2 4. When P is minimum, Angle of...

Hi everybody, Any one can tell me why the momentum of the wall is 2mv while a ball collides it?

Homework Statement A projectile, initial speed v = 20 m/s is supposed to hit a target D = 28.9 m away. However an H = 10 m high wall is placed halfway between the launching point and the target. What is the appropriate elevation angle? (in degrees). Homework Equations...

Homework Statement An automobile of mass 2000 kg is driven into a brick wall in a safety test. The bumper behaves like a Hooke’s-law spring. It has an effective spring constant of 5 × 106 N/m, and is observed to compress a distance of 1.67 cm as the car is brought to rest. What was the...

Although I do not remember the name of such question I am asking I am able to describe it in a sense. My Physics teacher had tried explaining and I was unable to conceive it, but maybe someone else can put it in laymen terms I suppose? I walk against the ground applying 100 N (random amount)...

Homework Statement An automobile of mass 3000 kg is driven into a brick wall in a safety test. The bumper behaves like a Hooke’s-law spring. It has an effective spring constant of 6 × 106 N/m, and is observed to compress a distance of 4.23 cm as the car is brought to rest. What was the...

Homework Statement Golfer hits a ball with speed Vo at angle @ above the horizontal ground. angle is fixed and no air resistance what is min speed for which the ball will clear a wall of height h and distance d away. your solution will get you in trouble if angle @ is such that tan@ < h/d...

An architectural feature of a building is a flat wall that is angled out over the footpath. Measurements (in meters) of three vertices of the wall were recorded against the x,y and z axes: x- axis is horizontal, the straight boundary of the footpath and the property on which the building sits...

Hi ! So recently I came across this interesting phenomenon that you can break through a strong concrete wall pretty easily by weakening it with certain holes drilled through it, following Hooke's law. I had heard about it before, but have never really thought about it. But now that I am, I...

Hi PF, I'm actually still an undergrad, so this is a long ways off, but I've been thinking about what possible route I want to take if/when I complete a Physics PhD program. I've come up with a couple reasons why the quant/finance path (or its analogue in 5-10 years) seems interesting to me...

Homework Statement A space station in outer space has a total surface area of 580m^2 with emissivity of 0.62. The temperature of the outside surface is 156K. The walls are 0.25m thick with an average thermal conductivity of 0.038W/mK. Find the temperature of the inner wall of the space...

Hi.. I am just confused normal forces. The definition of normal force is always perpendicular to the surface. But when we draw a free body diagram for a ladder lying against the wall. The normal force is like slanted towards the wall. Please explain thanks.

Homework Statement A 3.72 kg steel ball strikes a massive wall at 15.1 m/s at an angle of 58.6 with the plane of the wall. It bounces off with the same speed and angle. If the ball is in contact with the wall for .198s what is the average force exerted on the ball by the wall? Answer in...

HI I would like to test the thermal conductivity of r wall by K=Q*d/ A (t2-t1) K =conductivity d+=thickness A= area Q= heat flow my problem how I could simulate heat in my experiment and how I will measure the heat flow? could you please help me. Kind regards

Homework Statement [PLAIN]http://img571.imageshack.us/img571/4411/statics.jpg A Man weighing 180lb has climbed 60% of the ladder shown. The ladder weighs 30 lb. Find the forces the wall & floor resists (reactions). The angle the ladder makes with the floor is 60 degrees. Homework Equations...

Homework Statement A uniform 8 m 1500 kg beam is hinged to a wall and supported by a thin cable attached 2 m from the free end of the beam as shown in the figure. The beam is supported at an angle of 30 degrees above the horizontal. a) free diagram b) find the tension in the cable c) how...

Hey just a question about the field, I understand most of the jobs are on wall street if I'm a Canadian citizen is there any chance employers in the states would hire me, or is the paperwork too much? does it make a difference if i do grad school in the states? keep in mind I'm still in...

For a summer job I am employed to look into the use of composite paneling in place of sheet aluminum with stiffeners. I am suppose to find the required thickness of composite wall paneling in order to make a structure such as the one attached. Obviously it will depending on the material...

Mechanics problem: Ladder on a wall help please :( Homework Statement "A ladder of weight 200n and of length 5m rests with its lower end on a horizontal rough concrete surface and its upper end against a smooth wall. if the ladder just starts to slip when the angle between it and the concrete...