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.
Hey guys is my solution correct for the question below?
1. Homework Statement
Consider a 5.0 kg watermelon that is being accelerated at 2.0 m/s2 [up] by a cable. Find the tension in the cable.
Homework Equations
Fcable = m.a
The Attempt at a Solution
Fcable = m.a
= 5.0 kg(2.0)
= 10N
Homework Statement
An experiment is conducted on a "strange" planet to determine the acceleration due to the force of gravity there. A 2 meter length pendulum is suspended and put into horizontal circular path. Data collected: the pendulum makes 10 revolutions in 25 seconds while sweeping out a...
Homework Statement
There is a uniform slender bar which is suspended by two light inextensible strings and hangs in equilibrium. (if the mass and length of the bar are m and 2b )
Now, someone slightly knocks one end to make the bar rotate around the vertical axis with initial angular velocity...
I have a decent background in physics, but something that has always confused me is how to think about how the tension of the string in a tennis racquet affects how the ball leaves the strings. For example, the traditional lore in tennis is that tauter strings will give more control, whereas...
Is there any entropic gain when the surface of a liquid is minimised? Per example, molecules "enjoy" maximum entropy when they are at the interior. Is this valid?
Homework Statement
Consider a planar liquid-gas interface and a solid sphere partially immersed in liquid. A fraction of the solid surface area is wet by the liquid, call it ##A_{sl}##. The complement of the solid’s area is ‘wet’ by the gas, say ##A_{sg}##. There is also an area of contact...
While going through the derivation to find the surface tension of liquid i came with the formula which says that the surface tension is directly proportional to radius of the capillary so does that imply if we use a capillary with a greater radius so the same will give the different value of...
Homework Statement
A given pulley has a radius of 20 cm and moment of inertia 0.2 kgm2. The string going over it is attached to a vertical spring of spring constant 50 N/m on one end and a 1 kg mass on the other end. The system is released from rest with the spring at natural length. Find the...
Homework Statement
When an object is moving in a vertical circle attached to a string, it can withhold a maximum tension at the bottom of it's path. Derive an expression for the maximum velocity the object can sustain without the string breaking. No data is given, and everything should be...
I'm trying to design some novel cross bow designs and also trebuchet's with the trebuchet (similar to catapults to those who don't know) using springs or a combination of weight and springs. I'm looking into using linear springs and pullies for the crossbow depending on whether they can be...
Homework Statement
Find the total tension acting on a rod rotating about its end with an angular velocity of w as a function of its length x(length)
Homework Equations
F = ma[/B]
The Attempt at a Solution
Let the function be T(x) where x is the length of the rod.
Considering an interval...
Homework Statement
A mass of 0.5 kg is suspended from a flywheel as shown in FIGURE 2.
If the mass is released from rest and falls a distance of 0.5 m in 1.5 s.
Mass of wheel: 3kg
Outside rad. of gyration of wheel: 300mm
Radius of gyration: 212mm
calculate:
(a) The linear acceleration of the...
Homework Statement
Two objects (2kg and 3kg) are attached by a rope which can withstand maximum tension force of 350N. Forces acting on objects change with time (F=k*t) where k=10N/s.
After how many seconds will rope break. Solution is 25s.
3. Attempt at the solution:
I have tried...
1. The problem statement, all variables, and given/known data
Suppose a block is suspended by two strings, one, T1, is anchored at 30 degrees to the horizon, the other, T2, at 60 degrees to the horizon. If the block weighs 100 kg, what is the tension in the two strings?
Assume that:
The...
Homework Statement
In a physics experiment on static friction, two objects made of identical material are tied together with string. The first object has a mass of 5.0Kg and the second object has a mass of 3.0Kg. Students measure the maximum force of static friction as 31.4 N to move both...
Homework Statement
A hollow stirrer that has a diameter of 2.0 mm is inserted into a cup of water at 20∘C. The surface tension of water at that temperature is γ(surface tension) = 7.28×10−2 N/m.
What is the mass of the water supported by the surface tension in the stirrer?
Given:
d=2 mm...
Homework Statement
Homework Equations
Equation of Equilibrium (Horizontal and Vertical Forces, Moments)
Normal Stress = F/A
The Attempt at a Solution
I have already solved the solution for this problem. For part (a), I simply found the force in the link, and used the cross area where the...
Homework Statement
When a mother lifts he child with her foot (as shown in figure) what force should the upper muscle exert to lift her child at a constant speed?
Homework Equations
W = F x D
f = mg
I think these might be the right equations to use, correct me if I'm wrong.
The Attempt...
I know that when we strech the rope...all the points on that rope are under tension. But I do not understand how Newtons 3rd law of motion is applied when we work with tension.Any hep would be apreciated
Hello to everyone, merry christmas and happy new year! I was trying some exercises on the Feynman Lectures, on the topic of statics, and I came across with a problem which, simplified until where I am stuck, asks for the tension of a cable perpendicular to a bar with a weight on the top of it...
https://web.mst.edu/~numbere/CP/CHAPTER%203.htm
I have trouble understanding why the length used in 3.1.1 is pir^2. My notes don't explain what length we use either.
1. The problem statement, all variables and given/knowns
So basically,I am confused by this quote in David Morin's Problems and Solutions in Introductory Mechanics that says:
the tension in the tilted string has a nonzero horizontal component (except at the highest points where the tension is...
Hi everyone,
While studying surface tension I came across a(numerical example) problem which asks to find the force required to pull a circular glass plate of some given radius from the surface of water(assume plane of plate on water surface). Value of surface tension of water is also given in...
If you increase surface tension, the molecules at the surface are more strongly pulled into the center of mass due to the stronger attractive molecular forces.
-Why is it that when surface tension increases in a liquid, its surface decreases in area, but its volume does NOT change? (Volume...
Homework Statement
A mass ##m_1## is attached to a second mass ##m_2 > m_1## by an Acme (massless, unstretchable) string. ##m_1## sits on a frictionless inclined plane at an angle ##\theta## with the horizontal; ##m_2## is hanging over the high end of the plane, suspended by the taut string...
Homework Statement
A mass ##m_1## is attached to a second mass ##m_2## by an Acme (massless, unstretchable) string. ##m_1## sits on a frictionless table; ##m_2## is hanging over the ends of a table, suspended by the taut string from an Acme (frictionless, massless) pulley. At time ##t = 0##...
A prisoner in jail decides to escape by sliding to freedom down a rope provided by an
accomplice. He attaches the top end of the rope to a hook outside his window; the
bottom end of the rope hangs clear of the ground. The rope has a mass of 10 kg, and the
prisoner has a mass of 70 kg. The...
Homework Statement
The boom in the figure below (Figure 1) weighs 2450 N and is attached to a frictionless pivot at its lower end. It is not uniform; the distance of its center of gravity from the pivot is 35.5 % of its length.
Find the tension of the guy wire.
Homework Equations
Στ=0
∑F=0...
1.
Part One:
A mass M1 = 30 kg is suspended by a light string from the ceiling of a lift of mass M2 = 300kg.
If the lift accelerates upwards at 1 m/s2, what is the tension in the lift cable and in the string? (g=9.8 m/s)
Part Two:
If the string breaks when subjected to a tension of more than...
Homework Statement
So it's given the pipe has a inside diameter of 60cm and outside diameter of 70cm. the two ropes AC and AB are separated by a spreader bar. Wants us to find tension in the ropes. Also give is the density of concrete which is 2320kg.
Homework Equations
pi(r)^2*L=Area
The...
Homework Statement
I'm in need of a more conceptual answer, rather than numerical.
Say you have a block on a horizontal frictionless table (block 1). Then you have a string tied to block one and strung over a pulley that is at the right end of the table (the pulley has mass). On the other...
Hi
I want to study the topic of surface tension for the purpose of solving problems. I have textbooks like Halliday Resnick and Young Freedman. But these books don't cover the topic of surface tension. If you know any free, open resources to study this topic, please let me know
thanks
Homework Statement
A long rope with mass m = 10 kg is suspended from the ceiling and hangs vertically. A wave pulse is produced at the lower end of the rope and the pulse travels up the rope.
(a) Explain why the speed of the wave pulse change as it moves up the rope; does it increase or...
Homework Statement
A ball of mass m is attached to a rope of length L which has one end at the origin; the ball moves in a horizontal circle at constant speed v0 on a frictionless plane; the velocity is always at 90◦ to the rope. The ball has a charge q, and moves in a constant magnetic field...
Homework Statement
[/B]
Water rises in a capillary tube to certain height such that the upward surface due to surface tension is balanced by 7.5 X 10-4N
Force due to weight of the liquid. If the surface tension of water is 6 X 10-2Nm-1,the inner circumference of the capillary must be
Homework...
Homework Statement
[/B]
The question is from chapter 9 of "Exercises in Introductory Physics" by Leighton and Vogt.
The answer given in the book is ##R = 4.9 \times 10^{-5} \rm{cm}##.
Homework Equations
$$\sigma = \frac{\Delta P \cdot R}{4}$$
Where,
##\sigma## is the surface tension...
Homework Statement
2 & 3. The Attempt at a Solution
I've worked out:
The total force on the gate.
I have worked out the centre of pressure which I got a value of 10/3m (from the hinge).
For the moment about the hinge I got a value of 981,000Nm using the equation M=FN*X where X is the centre...
Hi, this is my first forum post - sorry if I'm in the wrong place, or I've done something wrong!
Homework Statement
Here goes: There is a beam of 0.5m length hinged to a wall at a right angle with 200N mass at the end of the beam. This is supported by a wire T at angle 30°. The question asks...
Homework Statement
A tugboat pulls two barges down the river. The barge connected to the tugboat, carrying coal, has an inertia of 2.0 × 105 kg, and the other barge, carrying pig iron, has an inertia of 3.1 × 105 kg.The resistive force between the coal barge and the water is 8.0 × 103 N, and...
Homework Statement
A rod of length L = 20 m and mass m = 50 kg juts out perpendicular to a wall. The rod is designed to pivot vertically about the point where it intersects the wall. A massless pulley is affixed to the wall a height h = 10 m above the rod. A cable is attached to the rod a...
Homework Statement
A locomotive has a mass of 40 tonnes.
In one situation, the locomotive is pulling two trucks, each of mass 10 tonnes
Calculate the tension in the coupling pulling the two trucks behind the locomotive.
The coupling is positioned such that it is linking the locomotive and the...
Homework Statement
A load of 1150 kg is suspended as shown in the figure. The angle θ1 = 57° and the angle θ2 = 36°.
(a) Calculate the tension in all three wires (that is, the magnitude of the tension force exerted by each of these wires):
Tension in left wire
Tension in right wire
Tension in...
Homework Statement
A ball of mass 620 g hangs from a spring whose stiffness is 115 Newtons per meter. A string is attached to the ball and you are pulling the string to the right, so that the ball hangs motionless, as shown in the figure. In this situation the spring is stretched, and its...
Homework Statement
A rope attached to a 19.0 kg wood sled pulls the sled up a 19.0° snow-covered hill. A 14.0 kg wood box rides on top of the sled.
EDIT: the actual question to be answered, oops.
What's the magnitude of the tension that will cause the box to slide?
Mass of box (mb) = 14.0kg...
a light inextensible string passes over a fixed pulley A, under a movable pulley B of mass M and then over a second fixed pulley C. A mass m is attached to one end of the string and a mass 3m is attached to the other end. the system is released from rest. (i) prove that the tension t in the...
Homework Statement
Why is the tension always tangent to the portion of the cable?
The correct situation is on points A and B.
Why can't be like on C and D?
Homework Equations
Newton's force-mass: ##F=ma##
The Attempt at a Solution
If i move the portion of the cable and examine, for...
Homework Statement
A hockey puck with mass 200 g is attached to a rope of length 62.0 cm and swung in a horizontal circle against the ice at a rate of 58.0 rpm. Assuming the ice is frictionless, what is the tension in the rope?
Homework Equations
FT = mω2r
The Attempt at a Solution
58rpm =...
Homework Statement
A 7kg mass is hung from a 1.5 m long massless string. It is released from rest with the string displaced by
an angle of 18 degrees from vertical.
a) Make a free body diagram of the forces on the mass just after it is released.
b) Find the tension in the string.
c) Find the...
Homework Statement
Two balls with masses m1=0.3 kg and m2=0.7 kg are connected by massless strings with lengths L1=0.2 m and L2=0.26 m, as shown. The arrangement of strings and masses rotates at constant angular frequency ω=57.6 radians/s around a fixed pivot point. Find the two tensions...