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 long string is constructed by joining the ends of two shorter strings. The tension in the strings
is the same but string I has 4 times the linear mass density of string II. When a sinusoidal
wave passes from string I to string II:
A. the frequency decreases by a...
when we try to measure surface tension of different concentrated solutions of n-butanol with a tensiometer, we have to go from lower to higher concentration and not the other way around. what is the reason for that?
A massless rod of length L attached to mass m and with axle to cart of mass M. The cart has a shape of equilateral triangle (edge L). the cart is at rest and its center of mass is above x=0 and a rod is perpendicular to the ground. the cart is free to move without friction. at time t=0 the mass...
Hi,
I'm a bit confused. Say you're bending a cylindrical pipe (tube, hollow cylinder). So the neutral axis of the pipe will be in the middle of the pipe and all the material on the inside of the bend (to one side of the neutral axis) will be in compression, while all the material on the...
Q: You are pulling your younger sister along in a small wheeled cart. You weigh 65.0 kg and the combined mass of your sister and the cart is 35.0 kg. You are pulling the cart via a short rope which you pull horizontally. You hold one end of the rope and your sister holds the other end. If you...
Homework Statement
What is the tension of the string?
Mass of piano string- 3.5g
Lenght of piano string- 75cm
Fundamental frecuency- 469Hz
Homework Equations
λ=2L/n ?
Dont know where to start.
Unfortunately there's no link to the test. This is from the test administered a month ago.
Homework Statement
A choppah is flying horizontally at constant speed. A perfectly flexible uniform cable is suspended beneath the choppah; air friction on the cable is NOT negligible.
Which of...
I attatch a rope of a constant density to the Moon and fasten it down to the surface. I set the other end in space right above Earth's atmosphere. The angular speed of the entire rope is brought up to the same angular speed as the Moon at time=0.
http://i.imgur.com/kHlVvnM.png
What would...
Homework Statement
A particle P of mass m is suspended from two strings AP and BP where A and B are attached to 2 points on a horizontal ceiling distance 5l/4 apart as shown in the figure. AP is inelastic and of length l. The modulus of elasticity of BP is λ. Show that the natural length L...
Why is one Tension Negative and the Other Positive -- Atwood Machines
Hello,
Please consider the following:
I am trying to understand how to solve for acceleration when dealing with Atwood machines. I keep getting hung up on one part: the direction of tension. In the image above, why is...
Homework Statement
Due to friction, a force of 400 N is required to pull a wooden box on the floor. The cord used to pull the box makes an angle of 56° horizontally.
How much tension should be on the cord to be able to pull the box?
Homework Equations
W = Fd * (cosθ)
Tension =...
Homework Statement
A 50 kg woman dangles a 50 kg mass from the end of a rope. If she stands on a frictionless surface and hangs the mass over a cliff with a pulley as shown, the tension in the rope will be...
Homework Equations
F = m*a
The Attempt at a Solution
(no calculator...
Homework Statement
Two bubbles, one of radius R and the other of radius 3R come into contact with each other. What is the distance between the centres of the two bubbles? Ignore the weight of the bubbles.
Homework Equations
p(inside bubble)= p(atm) + 4T/R where T is the surface tension and R...
Homework Statement
Please see the picture.
Homework Equations
How do they get this derivation?
The Attempt at a Solution
I know that lambda = 2L/n and f = nV/2L so I can somewhat rearrange it myself, but I do not know where the square root is coming from.
Homework Statement
The thin steel plate, weighing 82lb/ft^2, is being lifted slowly by the cables AC and BC. Compute the distance x and find the corresponding tension in each of the cables.
[See attachments for Figure]
Homework Equations
Summation of X = 0
Summation of Y = 0
Moment=Rd...
Homework Statement
The maximum tension the string can have without breaking is Tmax. Derive an expression for Vmax, the maximum speed the ball can have at point Q without breaking the string.
Homework Equations
F=ma
Vc=(mv^2)/r
T=mg+ma
The Attempt at a Solution
I thought I could do...
Hi. I am doing a physics project and we have been told by my lecturer to find out how to determine the surface tension of a liquid using Poiseulle's Law and to describe an experiment on how to do so. I have no idea how you could do this because none of the variables in the law relate to surface...
Hello,
I am looking for a general formula for the surface tension dependence with respect to temperature.
I am aware of the Eötvös rule (http://en.wikipedia.org/wiki/E%C3%B6tv%C3%B6s_rule), but I only found data for water, and wonder if there are some for other compounds.
Also, I wonder...
Homework Statement
"Block A has mass ma=4.0kg, and block B has mass mb=2.0kg. The coefficient of kinetic friction between block B and the horizontal plane is μk=0.50. The inclined plane is frictionless and at angle θ=30°. The pulley serves only to change the direction of the cord connecting...
Homework Statement
A cable is being used to lift a 350 kg piano into a helicopter. The cable can exert a maximum force of 5000 N without breaking. What is the maximum acceleration that the cable can give to the piano?
Homework Equations
w=mg
The Attempt at a Solution
w=?
a=...
My question is how do you find the acceleration if you don't know the Tension. If someone could just elaborate on the question as a whole it would be very helpful.
I didn't really know anything about how to do this problem.
My apologies for asking two questions in a short period of time, this is the last question I have. Hopefully one day I'll be skilled enough to answer everyone elses! :)
Homework Statement
An empty elevator has a mass of 722 kg. It moves between floors at a maximum speed of 6.00 m/s. The...
This was from my last exam. I got this problem wrong. I feel like I should have known how to do it but I blanked out or something. Just coming here to figure out how it's supposed to be done.
(This is from what I remember, numbers may be off from what was on the test)
I know I got it wrong...
I am studying surface tension and I am summing up what I have learned through books till now:
→ On a molecular level, due to unbalanced forces on the uppermost level, the liquid molecules tend to
go down the liquid.
→ As the molecules go down, the uppermost layer shrinks in size and tries...
Tension -- how is mechanical tension even defined?
Hello, I'm currently a student in AP Physics having a little trouble with the concept of tension, especially that of a pulley system or an Atwood machine.
First, how is tension even defined? Is it the reaction force to the applied force on...
1. The uniform beam shown in figure 5-15 weighs 500 N and supports a 700 N load. Find the tension in tie rope and the force of the hinge of the beam.
The answer according to the book must be 2.9 kN as the tension in tie rope and 2.0 kN as the force of the hinge of the beam.
2. The arm...
Homework Statement
A 0.70-kg disk with a rotational inertia given by MR^2/2 is free to rotate on a fixed horizontal axis suspended from the ceiling. A string is wrapped around the disk and a 2.0-kg mass hangs from the free end. If the string does not slip, then as the mass falls and the...
Homework Statement
My boat is tethered to a rope that can withstand a maximum of 8000 pounds of tension. The wind will exert, at maximum, 3000 pounds of force on the boat. How do I calculate the tension on the rope based on the angles that the rope is at? does it make a difference if the...
My boat is tethered to a rope that can withstand a maximum of 8000 pounds of tension. The wind will exert, at maximum, 3000 pounds of force on the boat. How do I calculate the tension on the rope based on the angles that the rope is at? does it make a difference if the boat is stationary, or if...
Can someone explain this please?? Weird pulley with Tension
Homework Statement
See attached picture for problem
Homework Equations
n/a
The Attempt at a Solution
The answer is B. No idea why.
Any help would be appreciated. Thanks!
Homework Statement
A capillary tube of radius r = 0.3mm is filled with water. A water droplet is hanging on the bottom of the tube, as shown in the picture. The water level is h = 5.2cm. Estimate the radius of curvature of the droplet R. The coefficient of surface tension of water is σ =...
Homework Statement
a 8kg ball is hanging from a 1.35m string. A 2 kg ball moving horizontally at 5m/s hits the hanging 8kg ball in an elastic collision. What is the tension in the string just after the collision?
Homework Equations
The Attempt at a Solution
Initially there is only...
Homework Statement
A 5 kg mass is attached to two ropes as indicated in the figure below. Find the tension in both ropes.
Homework Equations
Ʃy= 0 Ʃx = 0
The Attempt at a Solution
Mass of object: 5 * 9.81 = 49.05
T1 sin 30 - T2 cos 20 = 49.05
T1 cos 30 + T2 sin 20 = 0...
Tension and Pulleys...Cannot understand this problem
So this is NOT for homework, (I'm doing practice problems reviewing for a final), but this is a textbook question that might as well be homework.
This is the question:
Figure 5-53 shows a man sitting in a bosun’s chair that dangles...
Homework Statement
Determine whether each joint is in tension or compression
(correct answers on the image)
Homework Equations
sum of force = 0
The Attempt at a Solution
On Joint I, I don't understand why IH is in tension. The pin is exerting a horizontal force and...
Homework Statement
The diagram shows a block and pulley
system where all the surfaces are
frictionless, and all the pulleys are
massless and frictionless.
Express the magnitude of the acceleration of Block 2, a2, in terms of a1 and/or a3.
Homework Equations
F=ma
The...
Homework Statement
The diagram shows a block and pulley
system where all the surfaces are
frictionless, and all the pulleys are
massless and frictionless.
Once all Blocks have been let go, what is the ratio of the magnitude of the acceleration, a1, of block 1
to the magnitude of...
Homework Statement
A small square truss shown is supported by a pin joint at I and a roller at A. Label all members of the
truss by Z (for zero force member), C (for compression) or T (for tension).
Homework Equations
The Attempt at a Solution
So this was an exam question...
Homework Statement
The block moves at 2.3 m/s to the left (on a flat, horizontal surface). If μk, the coefficient of friction between the block and the floor, is .40, what is the tension in the rope? Also, the weight of the block is 9.8 NHomework Equations
No equations were given... but I used...
Homework Statement
A crane in a marble quarry is mounted on the rock walls of the quarry and is supporting a 2000 kg slab of marble as shown in the figure. The center of mass of the 900 kg boom is located one-third of the way from the pivot end of its 15-m length, as shown.
Given...
Homework Statement
http://i1345.photobucket.com/albums/p679/Duk_Bato/Untitled_zps84f60bfd.png
Homework Equations
ƩMA = Ʃ r x F
The Attempt at a Solution
1.6 * T+ 0.8 * sin 40 *T = 1.2 * 250
T (1.6 + 0.8 * sin 40 ) = 300
T = 300 / ( 1.6 + 0.8 * sin 40 )
T = 141.9 N
RX=...
Homework Statement
a 0.60 kg sphere rotates around a vertical shaft supported by 2 strings, as shown. if the tension in upper string is 18N calculate.
a) tension in lower string?
b) rotation rate (in rev/min) of the system.
Homework Equations
The Attempt at a Solution...
Hello, if I were to suspend a rubber stopper into a graduated cylinder filled with water, with the stopper half in the h2o and half out of it, how would i calculate the tension in the string? Experimentally, i would collect the displaced volume, density (1000kg/m3), and mass of stopper. I am...
Recently stumbled on this problem:
A uniform disk (I =½ MR2
) of mass 8.0 kg can rotate without
friction on a fixed axis. A string is wrapped around its
circumference and is attached to a 6.0 kg mass. The string does
not slip. What is the tension in the cord while the mass is...
1. Homework Statement [/b]
A stone mass 284g is twirled at a constant speed 12.4m/s in a vertical circle of radius 0.850m. Find the tension in the string at the top and at the bottom of the revolution. What is the maximum speed the stone can have if the string will break when the tension...
Homework Statement
A rigid weightless horizontal beam is hinged at a wall and is supported by two rods. The beam has a 8000 pound load applied at the end. Calculate the tension in each rod. The left rod is made of brass and has diameter of 1.25" and the right rod is made of aluminum and has a...
If the gymnast has a mass, m = 36.7 kg, and the angle θ = 4.0°, calculate the tension in the rope from which she is hanging.
ƩFx = T1x - T2x = 0
Then T1cos4 = T2cos4
T1 = T2 = T
ƩFy = 2Ty - mg
2Tsin4 = mg
T = mg/2sin4 = 2578 N
I have gotten the solution. I am just confused at...
Sometimes when I see pulley and rope questions people will say "for a non-extensible rope the tension is uniform throughout the rope". But I am now learning pulleys and rotational inertia and it seems to be necessary to consider the rope on either side of a pulley to have _different_ tension if...