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.
Homework Statement
A 1.3kg stone is whirled in a vertical circle at the end of a 0.83m long string. The tension in the string at the top of the circle is 6.4N. What is the tension in the string when the stone is at the bottom of the circle?
Homework Equations
Fc= mac
W=|F||Δd|cosθ...
Two buckets of sand hand from opposite ends of a rope that passes over an ideal pulley. One bucket is full and weighs 118 N; the other is only partly filled and weighs 58 N. After the buckets are released and allowed to move what is the tension in the rope
I drew a force diagram but all I...
Illinois Jones is being pulled from a snake pit with a rope that breaks if the tension in it exceeds 725 N. If Illinois Jones has a mass of 62 kg and the snake pit is 3.9 m deep, what is the minimum time necessary to pull our intrepid explorer from the pit?
F=ma and a=d/t^2
I put...
Homework Statement
A 1000N beam is loaded with a 2000N filing cabinet and supported by two cables. If the beam is 8 meters long and the filing cabinet is 2 meters from the left cable, what is the tension force in each cable?
Homework Equations
T= F /d
The Attempt at a Solution
For...
Homework Statement
Homework Equations
The Attempt at a Solution
For this problem, what I am confused about is the fact that the Z direction parts of the tension will tend to rotate in a direction different from the Y components of the tension and the 850 lb vertical force. I am not sure how to...
Homework Statement
I need to generate a field of B = 10 T at the center of a magnetic loop (coil). The coil should have r = 70 m. The coil material itself should be a cable of r = 0.2 m. The question, how much mechanical stress is applied throughout the loop? I'm trying to figure out, if such...
here is how the problem looks.
http://i39.tinypic.com/2d0j4wg.png
a pullstring walker is in the middle of a string that is connected to two mountain sides. the string formes an angle of 10 degrees under the horizontal. the walker has a mass of 50 KG. find the tension of the string
any...
Homework Statement
Two chests are connected by a 15 meters long rope attached to a ceiling hook hanging 4 meters high. The chest (1) at 5 meters from the hook has a velocity of 1/2 m/s away from the other chest (2). The chests remain flat on the ground and the rope is under tension.
What is the...
For this problem, my thinking was that since the top of the rod is fixed, then the only part that is elongating is the bottom, so I found the part elongating at AB and said that was the total elongation. I am not sure if this reasoning is sound. I suppose the other possibility would be to add up...
Homework Statement
Just started tension problems and having some trouble figuring out how to approach the problem. Thanks for any help in advance.
Consider a rocket that is taking off and towing a large container of trash. The
rocket’s engines exert a force, F, that causes the rocket and...
Homework Statement
m_2>m_1
The pulley rotates.
Find the tensions, T_1, T_2, T_3
Homework Equations
Newton's laws
The Attempt at a Solution
I know how to solve the problem if the pulley doesn't rotate because the systems would be in equilibrium (Newton's first law) and dividing...
Homework Statement
A 2.00kg aluminium block and a 6.00kg copper block are connected by a light string over a frictionless pulley. They sit on a steel surface, which is fixed, as shown in the figure, with a (let it be alpha lol) = 43.0deg. The coefficient of static friction for aluminum on steel...
Homework Statement
A circular conducting coil is present in space in the absence of any external electric and magnetic fields.A steady and constant current is flowing through the coil.What is the tension developed in the coil?.(Given current is 'I' and radius of coil is 'r')
Homework...
Homework Statement
A student pulls her 22-kg suitcase through the airport at constant velocity. The pull strap makes an angle of 50 degrees above the horizontal. (a) If the frictional force between suitcase and floor is 75N, what force is the student exerting? (b)What's the coefficient of...
Homework Statement
Cliff and Will are carrying a uniform 2.0m board of mass 77kg. Will is supporting the board at the end while cliff is 0.6m from the other end as shown in the following figure. Cliff has attached his lunch to his end of the board, and the tension in the string supporting...
A chandelier with mass m is attached to the ceiling of a large concert hall by two cables. Because the ceiling is covered with intricate architectural decorations (not indicated in the figure, which uses a humbler depiction), the workers who hung the chandelier couldn't attach the cables to the...
Homework Statement
On her flight home at Thanksgiving, Margaret decides to apply the physics she has learned in PHYC1300 to measure the speed of the aircraft when it takes off. She dangles her watch from a string while the aircraft accelerates down the runway. Draw a free body diagram of the...
Homework Statement
A bored but observant child on a moving train ties a ball to one end of a string and ties the other end to a light fixture on the ceiling of the train. When the train slows down, the child notices that the string is no longer hanging straight down but instead makes an angle...
Homework Statement
A bowling ball is suspended from a ceiling hook using a thin piece of rope. The rope is
exerting a 75 N force upward on the ball. Suppose that the rope is unhooked from the ceiling and pulled upward so that the
bowling ball rises 1.2 meters in 1.5 seconds. What will be...
Hi, I am currently enrolled in a first year Physics for Scientists and Engineers course at a university, but I am a biochemistry student without a physics background. I am relatively certain that the problem is a forces problem, but there is a chance that it could be energy as we have just begun...
So I have one attempt left and want to make sure my answer is correct, so double checking me would be super awesome!
You are given a pendulum composed of a 0.030 kg mass on the end of a 0.42 m long massless string. The pendulum is moved 25° from the vertical and released. Find the tension in...
Homework Statement
Hi everyone, I hope you're enjoying your weekends!
I've been trying this question for a while not having any luck, I'm hoping someone can tell me where I'm going wrong
The question is:
Two boxes are connected by a rope that passes through a pulley on the corner of a...
Give the correct tension, T, in the marked rope for each situation. The rope is held so the system is stationary. All ropes and pulleys are massless and frictionless.
Follow link for a picture of the pulley systems: http://i.imgur.com/2eBZpC3.jpg
A) T = W
B) T = W/2
C) T = W/3
D)...
A point A of the ceiling is directly above a point B of the floor 2.5 meters below. A and B are joined by a light spring of natural length 2 meters; the tension in the spring is then 20 Newtons. A Lump of Putty of weight 4 Newtons is now attached to the spring at the point 1 meter above the...
Just to clarify, if a string has a threshold of 100N, can the string be bent so that the tension in different parts individually doesn't exceed 100N yet the total force of the tensions do?
My question arises because of this question:
http://imgur.com/90NGY5p
http://imgur.com/ObRq5QM...
Homework Statement
A hanging 2.00-kg (19.6N) block begins to accelerate a 4.28-kg (41.94N) block on a horizontal surface. But a rope connected to the wall at 26.9 degrees brings the block to an equilibrium position. The coefficient of friction between the surface and the 4.28-kg (41.94N) block...
Homework Statement
In the figure below, the left-hand cable has a Tension T1 and makes an angle of 58° with the horizontal. The right-hand cable has a Tension T3 and makes an angle θ3 with the horizontal. A 97.6N weight is on the left and an 84N weight is on the right. The cable connecting the...
I need help understanding why in problems tension is modeled as T-mg = ma.
I understand there are different variations, but the main concept is what I need help with.
For example:
If i have 2 masses hanging off a pulley (m1=5kg & m2=10kg) then m1 has a downward force of 49N down. The...
I'm doing a physics lab right now and to find tension we use the equation T=m(g-a) where m is the suspended mass and t is tension. I'm not sure if g should be negative or positive. I'm guessing negative but I am not to sure.
Homework Statement
Two equal spheres of mass m are suspended by vertical strings so that they are in contact with their centres at the same level. A third equal sphere of mass m falls vertically and strikes elastically the other two simultaneously so that their centres at the instant of impact...
Homework Statement
The link to the problem is here, sorry I couldn't put the diagram in so thought it was better to link!
I need help with both questions, the attempt is for the first question.
https://www.dropbox.com/s/2stb476hp738w9l/Physics%20question.jpg
Many thanks for any help...
Homework Statement
http://imgur.com/vgLv6NY
The figure shows a system of masses and pulleys. Assume the masses slide without friction and the pulleys have negligible mass. Calculate the tension in the string.
Data: M1 = 2.1 kg; M2 = 1.4 kg; M3 = 1.6 kg;
Homework Equations
f=ma...
The pulley in (Figure 1) is suspended by a cord C. Suppose that m1 = 1.0kg and m2 = 3.9kg .
Determine the tension in the cord that supports the pulley C after the masses are released and before one hits the ground. Ignore the mass of the pulley and cords.
I'm having trouble getting started...
Homework Statement
A building is on fire and the occupant of a room ties together some bed sheets, attaches them to something immovable in the room and throws the bedsheet ‘rope’ out the window. The person weighs 800 N and the bed sheets can only hold a force of 600 N before they break. If...
The figures below represent capillaries of varying construction and arrangement. The diameter of the capillary portion is the same in each case, and all of the capillaries are constructed of glass, except where otherwise indicated. The equilibrium rise for water is shown at the left. Draw...
So I am thinking about this problem, and what I don't understand is how at that point A, it is below the x-z plane, but it is not given how far below it is. If I knew, I could solve for the tension in the y-direction and set it equal to the weight.
I must be able to use c and 8 in. to get me...
Homework Statement
Due to settlement of soil, a recently planted tree has started to lean. To straighten it, the cable system shown is used, where a turnbuckle on cable AB is periodically tightened to keep the cable taut as the tree gradually straightens. If the force in cable AB is 395 N...
The speaker is to be raised by increasing the separation between the points A
and B, but the ropes will break if the tension exceeds 4000 N. Find the maximum
possible separation between A and B; that is, when
the tensions in the ropes are equal to 4000 N.
The points are originally 6m...
Homework Statement
A solid uniform 45.0 kg ball of radius 0.16 m is supported against a vertical, frictionless wall using a thin 0.30 m wire of negligible mass. Find the tension in the wire.
Homework Equations
Sinθ = opposite/hypotenuse
Cosθ = (m*g)/T or T/(m*g); I'm not...
Homework Statement
This is a question from statics course.
Collar A is connected to a 50lb load on a frictionless horizontal rod. Determine magnitude of P to maintain equilibrium when x=4.5.
Im confused on the concept of Tension
I originally got the answer 11.25 lb like the images...
Homework Statement
a mass of 0.5kg is suspended from a flywheel. if the mass is released from rest and falls a distance of 0.5m in 1.5s, calculate : The tension in the rope. acceleration is 0.444ms-2.
Homework Equations
t-w = -ma
The Attempt at a Solution
t = m(ag)
t =...
Is the direction of surface tension on the surface of a liquid into the surface or parallel to it along the surface of the liquid? And how? I am confused between both of them because, when we take an example of line on the surface of a liquid, we say that liquid surface is behaving like a...
Homework Statement
PROBLEM: Choose a pair of measurements of the forces from parts A5, A6, or A7, where the forces on the sensors were quite different. Imagine there was an angle between one cart and the string. Assuming that the larger force was the true tension in the string, what is the...
So I'm having a very difficult time understanding how motor driven rollers are able to create different tension zone of a moving web. Look at this for example.
So is any zone between two driven rollers a tension zone? And how do these driven rollers change tension while also being able to...
I'm studying for the exam day after tommorow and while reading the practical on jaeger method I found the following...
P1-P2=2T/ r
r is the radius of the capillary tube
.....
advantages of this method..,
•contact angle is not needed
•can find surface tension of liquids like mercury
my...
Homework Statement
A wing on a light aircraft experiences an upward thrust of 10 kN.
This is counteracted by two steel wires each set at an angle of 30 degrees from the horizontal and of length of 4 meters.
The diameter or the wire is 10 mm, and Young's modulus for steel is 2.05*10^11 N/m^2...
Homework Statement Object A has mass 90.0 g and hangs from an insulated thread. When object B, which has a charge of +130 nC, is held nearby, A is attracted to it. In equilibrium, A hangs at an angle θ = 7.20° with respect to the vertical and is 5.00 cm to the left of B.
(a) What is the charge...