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
Two masses m and M (where M = 2m) are attached with strings. One mass m is suspended from a single verticle string held by two strings each at 45 degrees to the horizontal. The suspending string to the left at 45 degrees is attached to a fixed point. The string on the right...
Hi,
I'm new to PF so this is my first post. I have a real case scenario as my first thread in which I have a gravitational tensioning system that provides tension to a cable conveyor. The tensioning system includes a series of pulleys in a particular reeving arrangement that is fixed on one...
Homework Statement
The figure shows two masses hanging from a steel wire. The mass of the wire is 60.5 g . A wave pulse travels along the wire from point 1 to point 2 in 24.0 ms .
https://session.masteringphysics.com/problemAsset/1383975/6/knight_Figure_20_80.jpg
//What is mass m?
Homework...
Homework Statement
Homework Equations
principle of moments
The Attempt at a Solution
Okay so when resolving the forces horizontally and vertically, I get RA= T cosθ for horizontal component and RB= W + T sinθ for vertical component. To get my T, I chose to take moments about B, though I'm...
Homework Statement
Question 33. Just T1 and T2 are okay, I know T3
Homework Equations
F=ma
The Attempt at a Solution
325/2 = 162.5N
For T1: (162.5)(sin 60)
For T2: (162.5)(sin 40)
Thanks!
Homework Statement
A 30 kg neon sign is suspended by two cables, as shown. Three neighbourhood cats (5.0 kg each) find the sign a comfortable place. Calculate the tension in each cable when the cats are in the positions shown.
Ft1 = tension in left cable
Ft2 = tension in right cable...
I get that tension in a mass-less string arises because of electrostatic forces which arise because atoms of the string are pulled apart. I also understand that it is equal and opposite in direction at all points because otherwise the string would accelerate infinitely. But what about the last...
Homework Statement
the maximum force is F=F1 +F2 + T as shown in the textbook...
I can't understand why the tension of spring is also = F1...Is it because of the writer assume the spring is directly attached to the part P (upper part of the block) ??
Homework EquationsThe Attempt at a Solution
Solved Thank You : )
1. Homework Statement
A rigid, uniform, horizontal bar of mass m1 and length L is supported by two identical massless strings. (Figure 1) Both strings are vertical. String A is attached at a distance d < L/2 from the left end of the bar and is connected to the ceiling...
Homework Statement
Two blocks of weight 50N and 200N are connected by a cord rest on two inclined planes .determine the maximum tension in the cord when limiting friction condition develop in both blocks
R1=Reaction of weight 50N
R2=reaction of weight 200 N[/B]Homework Equations
for block of...
Homework Statement
A string is connected to a box A mass M at its left end and a box B mass 2M at its right end. Boxes A and B start pulling in opposite directions at the same time with forces which are time dependent and described by functions F(t)=Ct for box A and F(t)=Dt for box B. Values of...
Hi guys, I came across this question and I was wondering if someone could explain how we get:
TLsinO - mg(1/2LcosO) = 0
Your help would be much appreciated.
Homework Statement
A 0.020-kg mass is attached to a 1.2-m string and moves in a horizontal circle with a constant speed of 1.50 m/s, as shown in the figure. What is the measure of angle θ?
What is given:
m = 0.020kg
v = 1.50 m/s
L = 1.2 m
Homework Equations
Lengths
L = 1.2m
Lsinθ = r...
solved thank you : )
1. Homework Statement
A bucket of water of mass 14.2 kg is suspended by a rope wrapped around a windlass, that is a solid cylinder with diameter 0.350 m with mass 12.8 kg . The cylinder pivots on a frictionless axle through its center. The bucket is released from rest at...
Let's say I go to the store and purchase a rope. On the package of string, it says that the string can only withstand 100 Newtons before the rope snaps. I go home and test the tension in the rope. I tell a friend to pull on the rope at 99 Newtons while I pull on the rope with 99 Newtons. Did...
Hello,
I am trying to determine the tension in a belt conveyor transporting material to calculate the motor power required and also tensioning force needed on it. I wanted to know how the material weight that is being carried affects it. I considered the tension to be equal to the friction...
Homework Statement
What would be the effect on the following if the load torque is increased and the speed maintains constant:
a) the tension in the tight side of the belt
b) the tension in the slack side of the belt
c) the power transmitted
Homework EquationsThe Attempt at a Solution
I...
Homework Statement
I am just doing problems in 3000 solved physics problems in physics and I disagree with one of the answers and wanted to see if I am just an idiot or not
This is the picture of the problem
This the a picture of the solution in the book. It maybe hard to see the answers...
So two masses M1 and M2, are attached to each end of a cable, and the cable was hung over a pulley.
M1 is 5kg
M2 is 3kg
ΣF=20N
ΣM=8N
The system would be accelerating at 2.5ms-2 but how would you calculate the tension of the cable?
(g=10, cable is massless, pulley is frictionless)
Homework Statement
metal piece = 300N
As this metal piece is in balance, what is the tension in each cable?
Picture of the problem in attachment.
Homework EquationsThe Attempt at a SolutionW = 300*[0 0 1]
D to A:
vtda = tda [sin(37), sin(37)*sin(90), -cos(37)]
D to B:
vtdb = tdb...
Hi all, first post here. I'm a junior Physics/Math double major at UMass Amherst, playing with some problems over the summer. I'll get right into it.
A rope with constant tension T is deflected through the angle 2\theta_{0} by a smooth, fixed pulley. What is the force on the pulley?
It is...
These is my problem Assuming the surface on which A rests is frictionless and there is no drag on either of the bodies as they move at common acceleration.
Correct me if I’m wrong, I think the bodies should have a common acceleration since they’re connected
Why does F? exist??, I know that...
https://auddoq.dm2302.livefilestore.com/y2mGb2n5mfKxwU4nZlLmOvyElgDcG0-5GG9dGoP4AbrV1taK31XrOoPmeyf9x9RQZ8kXLi0WG2Etd0-I8bVWqOgVufahONs02hTGFS-SUwBVRyd-ajz5Eza-nrk9yWa7kF6kPFtMdPD6MGIpfwQMhywCLfOOuIO4-3tLe1_KjSf9V0/20150505_234057356_iOS.jpg?psid=1
if the image does not show here's the link...
Homework Statement
[/B]
Keep in mind this is a Top Gun-themed homework assignment.
Cougar comes in for a shaky landing. His 20422 kg airplane traveling at 85 m/s strikes the deck at 3.5 degrees below the horizontal. Cougar's plane snags the landing cable stretched across the deck. The landing...
Homework Statement
Homework Equations
a=Rα
The Attempt at a Solution
Free body diagrams:
For larger pulley, TR=Iα ⇒ T=½MRα
If this pulley rotates by some amount suchat x length of rope becomes free, and if I hold the smaller pulley at rest, then this extra length of rope comes bellow the...
Homework Statement
A mass m on a frictionless table is attached to a hanging mass M by a cord through a hole in the table; the hole has no frictional effect on the string. Find the condition (the speed of the mass and the radius of its circular motion) with which it must spin for M to remain at...
Homework Statement
Tarzan (mass of 80kg) has an 18m vine stretched horizontally from his hut to a pivot point P, as shown. He uses it to swing across the gorge to visit Jane's hut, starting from rest to conserve energy. One day Jane spoiled his plans by fastening a strong, thin, smooth...
Homework Statement
A diving sphere has a mass of 150,000.0kg and an external diameter of 7.000 meters. The sphere is anchored with a cable on the bottom of an ocean, at a depth of .8000 km. The density of sea water is 1025.0kg/m3.
A) What is the absolute pressure at that depth in pascals?
B)...
Homework Statement
Just wanted to check my work on this one.
An aluminum wire is clamped at each end under zero tension at room temperature. The tension in the wire is increased by reducing the temperature which results in a decrease in the wire's equilibrium length. What strain (ΔL/L) will...
Hello,
My friend needs to transfer construction objects across a pond, came up with this idea of tying a rope between the pond and a big tree then transfer objects through a pulley, I'd like to know how to calculate the tension and will the thin concrete wall withstand the load? Here a diagram...
Homework Statement
A string is held under tension, with both ends fixed, and has a fundamental frequency of 250 Hz. If the tension is doubled, what will the new frequency of the fundamental mode be?
Homework Equations
The Attempt at a Solution
I don't know how tension can affect the equation...
Homework Statement
Homework EquationsThe Attempt at a Solution
seems like Torque = r f sin theta should be used here but we don't know r.
Am I suppose to find the x and y components of the tension of the chain?
off topic : if the chain was moved so it would just be above the end of the rod...
Hi. I need help calculated the tension on bolts in an anchor plate.
The plate is bolted to a concrete wall with four bolts (see the included image). A bending moment acts on the plate, offset a bit up/down. The bending moment acts from up to down so that the upper two bolts are in tension and...
Homework Statement
Homework Equations
F=ma
The Attempt at a Solution
A FBD on the bottom block gives tension in C is equal to Mg. Then, a FBD on the middle block should give T_b-T_c=0, so tension on B should also be equal to Mg. Finally, a FBD on the top block gives the tension on A is...
Homework Statement
Two blocks, each with weight w, are held in place on a frictionless incline as shown in Figure. In terms of w and the angle a of the incline, calculate the tension in the rope connecting the blocks
Homework Equations
T = mg
The Attempt at a Solution
I cannot for figure out...
How do we find out the tension in a rotating ring of density ρ, radius r which is rotating with an angular velocity of ω and area of cross section A? And how do we know that this tension would be constant throughout the ring?
Homework Statement
There is a girder hanging from a crane by two cables. The girder is 2.6m long and hanging at an angle. The weight of the girder is 0.50 kN. Calculate the tensions of each cable.
Homework EquationsThe Attempt at a Solution
I would divide the two cables into their x and y...
Hi everyone,
What I understand is that tension only exists if there are two forces pulling on a rope in opposite directions. What I have also read is that due to Newton's third law, the rope actually pulls back with a force equal but opposite to the two applied forces, so the forces look a bit...
The question tells us that a tensile force of 80kN acts upon the thin rod and hence we know there will be an equal but opposite force on the other side. However, I don't understand why there are compressive forces on the tube? We aren't told about this in the question.
Thanks
Homework Statement
How to calculate initial tension or pretension in a system of two parallel springs.
F=5.33213N
K1+K2=53.0597
x=0.095
Individual springs have initial tension of 0.25N so I would expect an answer of 0.5N but I can't get there.
Homework Equations
F=(k1+k2)x
The Attempt at a...
I've been trying to write an equation for the tension of a string where a segment of the string is suspended between two points a set distance apart (the string extends beyond both points in both its initial and final conditions), and involves not only the periodicity of the string's movement...
Homework Statement
I had a set of old concrete steps, with a mass of about 2.5 metric tonnes (i.e., 2500 kg), which needed to be dragged across the yard. One way to make the job easier was to rig a block-and-tackle, which consisted of two pulleys. I used a thick rope to tie one pulley to the...
Homework Statement
A geologist is at the bottom of a mine shaft next to a box suspended by a vertical rope. The geologist sends a signal to his colleague at the top by initiating a wave pulse at the bottom of the rope that travels to the top of the rope. The mass of the box is 20.0 kg and the...
Homework Statement
2 cables are used to support a 24kg mass on a 1.6m long, 8kg uniform horizontal beam. The 24kg mass is 0.6m from the right cable. What is the tension in the right cable?
Homework Equations
torque = rFsinx
The Attempt at a Solution
Fy = ma = 24(9.8) = 235.2N
Fx = ...
Here is some background for this post and for future "Curiosity question" posts.
So last year in 10th grade, I took AP Calc AB and AP Physics B, and scored 5s on both, but a particularly high five on the physics, as I truly enjoy doing physics just for the bliss of it. Well this year, I stepped...