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.
TL;DR Summary: Ping-pong ball hanging static from infinite plane of charge and a string
Really struggling with this question. I'm not sure if I have set up the free body diagram correctly and don't know how to set up the x and y components
[Mentor Note -- thread moved from the schoolwork forums to GD as it seems like a more general question]
Homework Statement:: Topoisomerases help in relieving strain in the DNA ahead of the replication fork caused by the untwisting of the double helix (Topoisomerases are enzymes that...
The diagram for the problem is shown alongside. In the vertical (##\hat z##) direction we have ##T \cos \theta = mg##.
In the plane of the pendulum, if we take the pendulum bob at the left extreme end as shown in the diagram, we have ##T \sin \theta = \frac{mv^2}{r}## (the ##\hat x## axis of...
Homework Statement
In figure 12-34, a uniform beam of weight 500N and length 3m is suspended horizontally, on the left it is hinged to the wall and on the right end of the beam is a cable attached to support it. the cable is attached distance D up the wall from the hinge. The least amount of...
Homework Statement
There is a metal stick that is connected to the ceiling with another one. The angle between them is 60°. Calculate the tension force of the bottom one.
Homework Equations
T = f N
or actually none, except trygonometry
The Attempt at a Solution
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I tried using this...
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 person pulls three crates over a smooth horizontal floor at an angle of 34 degrees to the horizontal. The crates are connected to each other by identical horizontal strings A and B, each of which can support a maximum tension of 38.0 N before breaking. What is the...
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...
Homework Statement
A string prq which is fixed at p and where q is vertically below p. r is a smooth ring threaded on the string which is made to rotate at an angular velocity ω rad/s in a horizontal circle centre q, the string being taut.
If |pq| = 0.12 m, |pr| + |rq| = 0.18 m,
show that...
Hello!
I was hoping someone here could help me solve a real world problem. So my university pool has something called a bulkhead, which is basically a bridge that floats above the water so that people can walk across the shorter dimension of the rectangular pool (50 meters long, 25 yards wide)...
Homework Statement
Refer to figure please.
Homework Equations
∑Fy=0 before string is cut
The Attempt at a Solution
I tried summing the two forces in the y direction before the strings were cut which would be the two tensions at a sin40° and minus the weight of the ball(mg). That gave me T in...
Homework Statement
You come to a river and you see a vine you will use to swing across. Your mass is 75.0 kg, the vine is 18.0 m long, and the vine breaks when under 655 N of tension.
a) at what angle from the vertical will the vine break?
b) what should be the maximum tension supported by the...
Homework Statement
An accident victim with a broken leg is being placed in traction. The patient wears a special boot with a pulley attached to the sole. The foot and boot together have a mass of m = 4.0 kg, and the doctor has decided to hang a 6.0 kg mass from the rope. The boot is held...
Homework Statement
Homework EquationsThe Attempt at a Solution
Here is what i have done so far:
Fx = cos 45 T - Ff =ma
Fy=sin 45 T -mg+ Fn =ma
I found ff= uk * Fn = 0.5 *sin 45 +mg
fn = sin 45 +mg
Isolated for T in the x and y:
Tx = ma + Ff / cos 45 = 13.404
Ty = ma +mg - Fn / sin 45 =...
Homework Statement
A rod extends from a vertical wall at an angle of 27º from the horizontal. A 2.5-kg lamp is mounted at the end of the rod. After John throws his 300-g winter coat over the lamp, what is the magnitude of the tension in the rod?
The answers choices are:
A) 30N
B) 70N
C) 27N
D)...
Homework Statement
Find the Acceleration of the system and the tensions in the three ropes.
*If you can't see the picture there's a triangle (ABC), a train of four objects and three pulleys (one exactly at each corner). Side AC (hypotenuse) at the bottom, side AB to the left and side AC to the...
Homework Statement
A heavy sled is being pulled by two people as shown in the figure. The coefficient of static friction between the sled and the ground is μs = 0.579, and the kinetic friction coefficient is μk = 0.435. The combined mass of the sled and its load is m = 336 kg. The ropes are...