Surface tension is the tendency of liquid surfaces at rest to shrink into the minimum surface area possible. Surface tension is what allows heavier than water i.e., denser than water objects such as razor blades, insects (e.g. water striders), to float and slide on a water surface without becoming even partly submerged.
At liquid–air interfaces, surface tension results from the greater attraction of liquid molecules to each other (due to cohesion) than to the molecules in the air (due to adhesion).There are two primary mechanisms in play. One is an inward force on the surface molecules causing the liquid to contract. Second is a tangential force parallel to the surface of the liquid. This tangential force (per unit length) is generally referred to as the surface tension. The net effect is the liquid behaves as if its surface were covered with a stretched elastic membrane. But this analogy must not be taken too far as the tension in an elastic membrane is dependent on the amount of deformation of the membrane while surface tension is an inherent property of the liquid–air or liquid–vapour interface.Because of the relatively high attraction of water molecules to each other through a web of hydrogen bonds, water has a higher surface tension (72.8 millinewtons (mN) per meter at 20 °C) than most other liquids. Surface tension is an important factor in the phenomenon of capillarity.
Surface tension has the dimension of force per unit length, or of energy per unit area. The two are equivalent, but when referring to energy per unit of area, it is common to use the term surface energy, which is a more general term in the sense that it applies also to solids.
In materials science, surface tension is used for either surface stress or surface energy.
Hi,
I have a revision book that has an example in it for the tension on a rope
if a 20 Newton force is hanging on the centre of a rope suspended between two points.
The rope dips 25 Degrees either side. So effectively an upside down pair of right angled triangles is formed.
The Hypoteneuse...
I was asked to explain how different factors affect surface tension. I can understand how temperature plays a role.
1) Contamination:
Increase in contamination decreases surface tension. I tried thinking about it.I thought maybe the particles that contaminate the fluid get in the way and...
Homework Statement
Determine the tension cable A and B and the x , y , z reaction of the ball and socket joint at C .
Homework EquationsThe Attempt at a Solution
I let the reaction of ball and socket joint at C = Fx , Fy and Fz
Sum of force in z direction :
TA +TB +FZ= 400
Sum of force in...
Homework Statement
I'm currently following the textbook Advanced Engineering Mathematics by Erwin Kreyszig.
I'm learning the derivation of the Wave equation using the method shown in the book, but when I reached the final part of the derivation, the working just confuses me.
(1/Δx)[ (u/dx)|...
I have attached a picture so that it is easier to visualize this problem. The information is all in it. The number scribbles are just my attempts to solve it:
http://i65.tinypic.com/2qlbn9h.jpg
The current topic we are on in class is Newton's Laws and we have covered moments and equilibrium...
I've read a couple other threads about this issue. And one even addressed my exact question but the answer didn't help me understand this at all.
In an Atwood machine, why isn't the total force on a mass = its gravity minus the gravity of the mass on the other side?
I keep seeing tension in...
Hello. I am having some trouble to understand conceptually the behaviour of such a system:
So, both blocks are in contact with the floor, one has mass M and the other has mass m. Then we apply an upwards force F on the axel of the pulley. How does the system behave?
My initial thought is...
Please find the attached (http://s23.postimg.org/ropds44ob/Capture.jpg). I know how to get the shear force for each bolt using bolt analysis. But I don't know how to get the tension/compression force of the bolt when it position is not symmetric.
*I already download some excel from internet...
Homework Statement
A model airplane has a small gas powered motor in it to allow it to fly. It is tethered its controller by a long
cord. The plane will fly in a circle at the end of this cord around the controller who uses the tether to control
the altitude of flight of the plane. Currently...
Homework Statement
A transverse pulse is propagating on a 2.0 m long string of mass 50 g. The pulse is
described by the equation:
y(x,t)=pi/(pi+(3x/2+pi(t))^2)
, with x and y in meters, and t in seconds.
Find the tension in the string.
Homework Equations
y=asin(wt+thetha)[/B]The Attempt at...
Homework Statement
A spider builds a web using 4 strands as support.
Strand 1: 21mN [20°E of N]
Strand 2: 16mN [60°E of S]
Strand 3: 18mN [40°W of S]
Determine the force of tension in strand 4 assuming the web is stable.
Homework Equations
r(cosθ) - N/S components
r(sinθ) - E/W components
The...
My question arises from trying to get the correct sign convention for a pulley that has two boxes attached by a massless rope. one box is to the left of the pulley and the other box is hanging down below the pulley.
If I take the counter clockwise direction to be negative, and set up my...
Homework Statement
What is the tension in a pendulum? Is T=mgcos(theta) or is T=mg/(cos(theta)) ?
and is the x component of tension is mgsin(theta) and this is the restoring force?
Homework Equations
Fnet=ma
Fg=mg
The Attempt at a Solution
Maybe it depends on the problem given? But I am...
Homework Statement
Since the image is not clear ,the blocks on the left are 1 Kg(top) and 5kg(bottom) connected by a spring. On the right are 1Kg(top) and 2Kg(bottom) .The bottom right string is cut .
Homework EquationsThe Attempt at a SolutionSuppose T1 is the tension in string AB , T2 in...
Homework Statement
LETTER d only [/B]
Homework Equations
Fnet = ma
The Attempt at a Solution
So I considered 2m independently and set its net force equal to its gravity minus its tension.
(2m)a = Fg - Ft = (2m)g - Ft
I then rearranged the equation so that Ft = (2m)g - (2m)a = 2m(g-a)...
Homework Statement
Is this correct? The sum of the forces in the Y have to be zero and there is only two y-components so it's pretty simple to determine this. There are also only two x-components so those will also cancel each other out as they have to go in opposite directions to balance as...
Homework Statement
A cat is stuck in a tree. You are designated with the job to get it out, yet you do not want to climb the tree, because you may get stuck as well. Instead you set up a pulley system. A rope (consider it massless) runs from the seat you sit on over an ideal pulley and then to...
Homework Statement
Hey guys. The other day I was doing some physics questions, studying for the finals, you know the story. Me and my friend came across this physics question where:
There is a particle of mass 2kg (m) hanging by a mass-less string that went around a pulley with mass 4kg (M)...
Homework Statement
A tugboat pulls two barges down the river. The barge connected to the tugboat, carrying coal, has an
inertia of 2.2 × 105 kg, and the other barge, carrying pig iron, has an inertia of 3.5 × 105 kg.The resistive
force between the coal barge and the water is 8.0 × 103 N, and...
Hi. I am having some difficulty with circular motion.An object is spun vertically on a rope a) when would the string be most likely to break?
The object would most likely to break when it has the most tension, so at the bottom of the circle it is Ft-Fg=Mv^2/r which is (Ft=Mv^2/r + Fg) while the...
Homework Statement
A car of mass (m) is attached to a cable of length (L) to a rotating pole. The car will speed up and travel in a circle. If the maximum speed of the car is vmax, what should the minimum strength of the cable connecting the car to the pole be? Note the surface is not...
Homework Statement
An 11 kg traffic light hangs fro ma structure as shown.
The aluminium pole AB is 7.5 m long, and weighs 8 kg. Determine the tension in cord CD
Homework Equations
T = rf[/B]The Attempt at a Solution
Ignore the AC height of 3.8 m, and replace it with an AD length of 7.5...
Hi,
I need some guidance on the following problem, please.
A daredevil attempts to walk the full length of suspended. A 20 kg wrecking ball hangs at the end of this uniform beam of length 4 m and mass 10 kg and is attached to a hinged wall at an angle of 53 degrees. A cable attached to the wall...
Homework Statement
A child pulls a friend on a sled. The child maintains a constant tension of 29.4 N in the rope. The combined mass of the friend and sled is 30.0 kg, and the coefficient of sliding friction between the sled and snow is 0.1. How far can the child pull her friend in 6 sec...
Hello this is my first question here :) So here is my problem:
We have a circle radius 50 (m), made out of iron wire
mass 5.506206591207348477884587 Kg per meter of rope.
Rope diameter 11/8 inces or 3.4925cm
The wire rotates with 3 rpm in zero gravity
1)How can i calculate the tension? Thx...
Homework Statement
A 4.5-kg bowling ball is perched on a concrete ledge directly below your dorm room window, with the side of the ball opposite the holes touching the wall. Wanting to hold the ball in place so that it doesn't roll off and land on somebody, you manage to hook one of the holes...
Homework Statement
So In this problem, I have two strings, one string pulls with pounds and is 30 degrees away from an imaginary line straight down of of the two strings and there are no variables or degrees given for the second string. The weight is 20 pounds. I have been looking at this...
Homework Statement
the cord shown have supports a force of 500N and warps over the frictionless pulley , determine the tension in the cord at A and the horizontal and vertical component of reactions at A .
Homework EquationsThe Attempt at a Solution
for the moment about A , the author gave...
Homework Statement
Hi all. What concerns me here is that it's worth 10 marks, but the solution I've tried only takes 2 steps. Am I missing some relation between the frame support and the pulley altering the components of the tension, or is the solution really just a basic trig conversion...
For question about the falling object
we will always take T=mg+ma
so we take mg and ma positive
for question about the object rolling down the inclined plane
we will say that mg sin theta - ma=0
although mg sin theta and ma is still on the same direction, we take mg sin theta positive but we...
Homework Statement
Identical ropes were tied to two trees, and two men, A and B, started shaking the free ends at the same instant a short while ago (Figure 1) .
Which rope has the greater tension?
Which man is shaking with the greater frequency?
Homework Equations
T=1/f λf=v
The Attempt...
Homework Statement
Homework Equations
My assumption:-
if one of the ropes have been cut, it mean the object just hang VERTICALLY with one rope with 5N load on it.Is it my assumption is correct?
The Attempt at a Solution
Tension of the other rope = 5N (is it correct)?? base on my assumption...
Hi all,
I am doing a High Velocity Impact testing using a gas gun
I have to figure out
a) is my test running well and I am not getting any reflection?
Please correct me or help in calculating if I am wrong at any point. I guess, I can figure out by calculating the time required for the...
Homework Statement
An object with a mass of 18 kg is suspended from 2 cables as shown in the below diagram. The tensions in the cables are T1 and T2.
a) Draw a free-body diagram for the object. (already solved)
b) Find the tension in both ropes, T1 and T2. (already solved)
c) If string 2 were...
If a string can handle a max tension of 85 N what is the largest mass that could be lifted with this string if it is lifted with an acceleration of 2.0 m/s^2 up on the moon?
Let up be positive in value.
Ft = - 85 N, a = 2.0 m/s^2, Fg = -1.6 m/s^2
Homework Equations
F = ma -> Fg = mg -> Ft =...
Homework Statement
A rod extends from a vertical wall at an angle of 27º from the horizontal. A 2.5-kg lamp is mounted at the end of the rod. After John throws his 300-g winter coat over the lamp, what is the magnitude of the tension in the rod?
The answers choices are:
A) 30N
B) 70N
C) 27N
D)...
Homework Statement
Find the Acceleration of the system and the tensions in the three ropes.
*If you can't see the picture there's a triangle (ABC), a train of four objects and three pulleys (one exactly at each corner). Side AC (hypotenuse) at the bottom, side AB to the left and side AC to the...
Homework Statement
Isn’t this question same concept as the note as I posted ? I found
P = T + F1+F2= 50(0.3)(9.81) + 50(0.3)(9.81) + (50+100)(0.35)(9.81) = 809.3N
But the ans given is 662.2 N ..
Homework EquationsThe Attempt at a Solution
Homework Statement
The fundamental frequency of vibration of a particular string is f. What would the fundamental frequency be if the length of the string were to be halved and the tension in it were to be increased by a factor of 4?
Answer: 4 f
2. The attempt at a solution
We have f = f1...
The Question:
Using a simply pulley/rope system, a crewman on an Arctic expedition is trying to lower a 5.65-kg crate to the bottom of a steep ravine of height 23.9 meters. The 60.9-kg crewman is walking along holding the rope, being careful to lower the crate at a constant speed of 1.50 m/s...
I have been wanting to write an equation which predicts the tension on a circular membrane (AKA drumhead). However, I'm not sure that my answer is on the right kind of track, if it's even correct.
As for the procedures I took, first I started with the equation for tension on a string, which I...
1. Homework Statement
In one of the versions of the "Giant Swing", the seat is connected to two cables, one of which is horizontal (Figure 1) . The seat swings in a horizontal circle at a rate of 33.0 rev/min .
If the seat weighs 295 N and a 869-N person is sitting in it, find the tension in...
If there is a 70N tension in a rope attached to a 4.0 kg bucket, what will be the vertical acceleration of the bucket?
I'm not really sure how to do this. I can find tension but not acceleration. I think I'm missing something simple. I'm also confused about the direction because it doesn't...
I solved the equilibrium equations and found that link BD is in tension while link CE is in compression, but my resulting answers for normal stress were wrong.
The solutions show that the cross area to be used for normal stress at links BD and CE should be different. Link BD should incorporate...
Homework Statement
the metal rod is supported by another metal rod at one end . The metal rod is supported by another metal rod at the end. so , the direction of tension of metal rod is acted upward , right ?( this is the initial prediction) But , i was told that the tension that we get from...
Homework Statement
Explain why the force diagram is as shown:
[PLAIN]http://
Homework EquationsThe Attempt at a Solution
[/B]
For the system, the gravity vector makes sense. However, I don not understand exactly why there are three tension forces. First of all, to me, it would seem that...
Homework Statement
Let's say the metal rod is held by a cable and supported by a pin at the bottom, the reaction of thr cable is acted downwards... Why?
Homework EquationsThe Attempt at a Solution
Homework Statement
In the figure below, the objects are attached to spring balances calibrated in Newtons. Give the readings of the balances in each case, assuming that the strings are massless and the incline is frictionless.
I need help with (d). If the picture's too grainy to read off...