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.
A mass m = 0.15 kg is attached to a massless string and rotates at constant speed v = 4 m/s in a horizontal circle of radius 2 m. The tension T (in N) in the string is: (a) 1.1 (b) 1.9 (c) 2.4 (d) 3.3 (e) 4.9
I would assume that first I calculate the centripetal acceleration by using v^2/r =...
Homework Statement
A grid made of ropes is suspended by its four corners with strings tied to four different points on a building. Three of which are fixed and fourth is attached to a pulley which is in turn fixed to the building.
Given data :
Grid mass is 25 kilogram suspended at a height of...
Homework Statement
You are presented with a circumstance in which three children are playing on a frozen pond. The three small children of mass 20.00 kg, 24.00 kg, and 16.00 kg, respectively, hold hands, and are pulled across a smooth frozen pond by a larger boy on skates, who pulls a...
Homework Statement
Block B hangs from Block A by a Rope 1. Rope 2 hangs below Block B.
Each block has a mass of 1.0 kg.
Each rope has a mass of 250 g.
The entire assembly is accelerating upward at 3.00 m/s^2 by force F.
A. What is F?
B. What is the tension at the top of Rope 1?
C. What is the...
Homework Statement
Homework EquationsThe Attempt at a Solution
Trying to answer it before solving it,
The maximum tension force is mg, so the average has to be less than this. Hence, the option (a) and (c) are not correct.
## T = mg \cos \theta ##, where ## \theta ## is the angle between...
What I've attempted to do is resolve vertically and horizontally:
T1sin(30)+T2sinΘ+T2=9g
T2cosΘ=T1cos30
After that... I'm completely stuck. Any help would be appreciated, I've spent so long on this I bet I'm just missing one simple thing.
Thanks in advance
Homework Statement
A box weighs 12.6kg and it is dragged with a rope(it weighs 1.4kg and the length is 60cm).The force dragging the box is F=80N.The coefficient of kinetic friction is 0,5.
What is the tension of the rope in the middle?(Answer:17N)
Homework Equations
No revelant equations
The...
A uniform 41.0 kg scaffold of length 5.8 m is supported by two light cables, as shown below. A 78.0 kg painter stands 1.0 m from the left end of the scaffold, and his painting equipment is 1.6 m from the right end. If the tension in the left cable is twice that in the right cable, find the...
Hi, I have a homework and I kind of stuck on it. Here is the question:
A 17 kg object on a rough ramp (coefficient of friction = 0.35N, ramp's angle = 25 degrees) is connected to a vertically hanging object via a pulley with I = 23 kg m^2 and the radius is 0.25m. The hanging object had weight...
Homework Statement
A worker is going to attempt to pull a 90-kg box across a level floor by a rope that makes an angle of 35° with the floor. The tension in the rope is gradually increased until the box just starts to move. If the coefficient of kinetic friction is 0.36 and the coefficient of...
Homework Statement
A second harmonic standing wave has the known quantities of Amplitude (max y at antinode) A, maximum velocity (y=0 at antinode) v, string length L, tension in the string T.
Given that we know that it is second harmonic, we can assume that λ = L
How can one determine the...
Homework Statement
Homework Equations
F = mv^2/R
The Attempt at a Solution
I got that T1max = T2max because when i plugged into my formula for centripetal force, i get that both ropes end up with mv^2/R which means they are equal everywhere... Is this correct?
Homework Statement
Homework Equations
F = ma
The Attempt at a Solution
So , i drew a freebody diagram for the 6k gram block, and the tension to the right of I call T2.
Therefore, the force of gravity component parallel to T2 is (6*9.8)sin30. Therefore, T2 is equal to this value which i...
Homework Statement
Homework Equations
Weight = Tension in y direction??
The Attempt at a Solution
I thought that W = the tension in the y direction of the two cables so that T2y and T1y are both 20 N each. Thus, i calculated that the tension in AC is 33 N ( cos(53.1) = 20/T1 --> T1 = 20/...
Homework Statement
Homework Equations
Ook, so I'm really bad at physics, and i need someone to help explain why the answer is P=T+25 N
I thought it is P+T = 125
The Attempt at a Solution
Since the system is in constant velocity, then Fnet = 0 so that P + T + W = 0 Why isn't it P + T + 125...
Homework Statement
Where does T2cos(theta) come from ? Isn't mv^2/R the centripetal force which is the tension of rope 2?
Homework Equations
Fc = mv^2/R
3. Solution
Wait! The horizontal component of the circle is the centripetal force? So that part is mv^2/R?
I got confused and thought...
Homework Statement
Homework EquationsThe Attempt at a Solution
I have the solution of the questions and I don't understand why the tension in Q7 is assumed to be uniform throughout the rope, however the tension in Q7 is not the same throughout the rope (i.e. for a segment dl, the tension in...
Hi everyone,
I have attached a sketch which may help understand the question I have.
I have a hinged flap which hangs vertically (hinge at top). The flap weight is 10kN and it is 1.8m tall (uniform mass). At the bottom of the flap is a lifting eye.
2.5m away and 0.3m above height of the hinge...
Homework Statement
[/B]
A rope with uniform mass distribution is attached to a spaceship. At the end of this rope, there is a mass, m. The length of the rope - l.
Point A - where the rope is attached to a spaceship
Point B - in the middle of the rope.
The whole system moves with the same...
Considering the figure, (a) what is the tension along the wire 1?
(b) What is the tension along wire 1 immediately after the wire 2 is cut?
Now, if I put myself in a reference frame with y-axis along ##\vec{g}## (with inverse direction) the part (a) is $$\begin{cases} T_1\cdot cos\theta -mg=0...
Homework Statement
The speed of the pendulum bob remains constant
as it travels around the circle
(a) Over one complete circle, how
much work does the tension force F do on the bob? (i) A positive amount; (ii) a negative
amount; (iii) zero.
(b) Over one complete circle, how much work does...
Homework Statement
State the boundary condition which must be met at a point where the string of question 2 is fixed.
Hence find the real standing wave solutions to the wave equation, and determine the allowed oscillation frequencies, when such a string of length ##L## is fixed at its ends...
Homework Statement
I solved the first part of the problem correctly. Here there is the second part:
assume that m1 is large enough so that the rope starts to slip and the masses start to move. What is a, the magnitude of the acceleration of the masses after sliding has begun?
Hint: Just when...
Homework Statement
A 2 kg tetherball swings around a vertical pole attached to two ropes each at a 30 degree angle from vertical. Each supporting rope is 1.5 meters long, and the ball travels at 8 m/s long.
Homework Equations
The question doesn't ask what they're looking for, so I assume they...
Homework Statement
A 5000 kg car rests on a 32° slanted ramp attached to a trailer. Only a cable running from the trailer to the car prevents the car from rolling off the ramp (the car's transmission is in neutral and its brakes are off). Find the tension in the cable and the force that the...
Homework Statement
A rope of uniform mass density is passed above the top of a fixed pipe of circular cross section.
Points B and C - the points where the rope loses contact with the pipe.
Points A and D - at the ends of the rope
The length of the segment AB = 2d
The length of the segment CD...
Its getting hard for me to deal with the problems related to tension and reason behind this is not clear understanding of the concept so i have few questions on this.
What causes tension in a rope/string(i think its related to electromagnetism, but i am not getting the clear idea behind this)...
Homework Statement
When the motor in the figure below lowers the m = 1200kg mass, it produces a tension of 1.15E+4N in the cable on the right side of the pulley. The pulley has a moment of inertia of 71.3kgm^2 and a radius of 0.794m. The cable rides over the pulley without slipping. Determine...
I have no idea where to begin. Any help would be appreciated.
Once upon a time there was a terribly wicked King who had a daughter who was very beautiful. The daughter was in love with a handsome prince, and before long the prince and the princess had become inseparable. The King, however, was...
I attached an image of the problem but here's an explanation.
A 5.50kg mass is hanging from a rope that is attached to two other ropes. Rope 1 is 40 degrees below the negative horizontal and Rope 2 is 40 degrees to the right of the positive vertical. Find the tension in rope 1.I understand...
Homework Statement
Two objects of 2.8kg and 4.2kg are connected by an inextensible cord. The object's at rest on a plane inclined 22°, determine the object's acceleration and tension in the cord if a 60N force is used to push the object downward.
Homework Equations
ΣFnet = ma
the plane is...
1. The problem statement, all variables, and given/known data
A block of mass m1 = 2.00kg is attached to a rope of length L1 = 0.50m, which is fixed at one end to a table. The mass moves in a horizontal circle supported by a frictionless table. A second block of mass m2 = 1.25kg is attached to...
Hello Everyone,
I was learning about prestressed concrete and how it works. Concrete is very strong under compression but weak under tension. In the case of prestressed concrete, the steel bars are pulled and become elongated.
How much do the steel bars elongate when they are pulled?
The...
Homework Statement
A constant force F pulls a rope vertically upward. The rope is lifting a block of mass M, to which it is attached. The rope is of uniform composition, and has mass m and length L. Find the tension in the rope at a position y along its length. (The tension will not...
Hello,
(I'm not sure if this is the right place to ask.) I'm taking AP Physics 1, having never taken physics before.
In class we are doing forces with Newton's Laws, and a little bit of free body diagrams (if I remember the name correctly).
For homework, we got a worksheet with questions about...
Homework Statement
Problem image: https://prnt.sc/gvhjso
In this case I have to find the reaction forces at the point E (the Fx, Fy, and the Moment at point E) by using the given data. The 20kN forces at the load AC are concentrated, and are 1.8m far from each other. The tension of the cable is...
Homework Statement
A telephone wire of mass m is strung between two poles, making an angle θ with the horizontal at each end find the tension at the center. in terms of Theta Mass and G
The attempt at a solution
i assumed it was T= mg/2sintheta using the same logic as the tight rope walker...
[Source]
Both these masses are of 1kg each and the scale reads in Newtons.
The intuitive answer for the reading of the scale is about 20N because it is being pulled by 10N from each side.
However, this is clearly not true as the scale reads about 10N. Why is it so?
I believe that I am...
Hi, I'm quite confused about vertical circular motion (particularly at minimum speed) and would appreciate any help.
I'm confused about velocity in a "loop the loop" situation. Say (theoretically) a car was going minimum speed around a loop (which I understand is sqrt of rg). Therefore the total...
There seems to be some -at least- conceptual difference between particles in QFT which is just a point -eventually- in the field AND the particle in QM which is described by a wavefunction which is extended in space. As if QFT somehow "collapses" the wavefunction.
Homework Statement
A frictionless surface is inclined at an angle of 30.0° to the horizontal. A 270-g block on the ramp is attached to a 75.0-g block using a pulley, as shown in Figure 4-62. (a) Draw two free-body diagrams, one for the 270-g block and the other for the 75.0-g block. (b) Find...
Well, this might be the stupidest question ever, but whatever. I was just thinking about a problem where a pendulum is attached to something that spins around itself (image below) and thought that maybe Centripetal Force might be a projection of tension on a vector that is perpendicular to ω...
Hello
How the surface tension is measured for molten metals? I have heard about the sessile drop, but it seems to be a very inaccurate method...
Thank you for your time.
Regards.
Dear Everyone,
A sphere is attached to the ceiling of an elevator by a string. A second sphere is attached to the first one by a second string. Both strings are of negligible mass. Here $m_1=m_2=m=3.52\text{ kg}$.
(a) The elevator starts from rest and accelerates downward with...
Homework Statement
(Problem #1 on this page.)[/B]
Homework Equations
##v=\sqrt { \frac { T }{ \mu } } =\lambda f##
The Attempt at a Solution
I don't think there is enough information,
##v=\sqrt { \frac { Mg }{ m/L } } ##
m, the mass of the string is not given
Homework Statement
0.5 kg bird lands on wire of telephone poles that are 50m apart. The wire sags 0.15m. What's the tension in the wire? Ignore weight of the wire
Homework EquationsThe Attempt at a Solution
I figured out the angle that would be created (0.34 degrees) when the bird lands and...
Homework Statement
Hi. My problem (from my picture) is which string (A or B) has more tension when the 50g object accelerates down and both carts move left. The pulley and string can be considered massless and frictionless.
Homework Equations
Fnet = m*a
The Attempt at a Solution
My thinking...
Suppose we have a dome of fabric supported by radial rigid beams. The pressure (air or water pressure) outside the dome is significantly higher than inside the dome (perhaps the inside is even at vacuum).
Because the material is fabric (non rigid) the compressive force from the higher pressure...
I want to demonstrate to flat earthers that water does indeed stick to a ball. If we want to do a scale model of the earth, at which radius will gravity overcome the surface tension?
Homework Statement
The tension between the 6 kg and 4 kg object
as=2.1m/s
Fnet = 40N
assume 0.4 kinetic friction coefficent
Homework Equations
T1- Fnet = mas
The Attempt at a Solution
acceleration is negative because the object is decelerating as it goes up the slope
so T1-40N = 6(-2.1)
T1 =...