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
why i figure b , the direction of FBD is in downward direction , whereas in a , its in upward directon
Homework EquationsThe Attempt at a Solution
Homework Statement
This is a solved problem. It is attached. Why is sin theta horizontal, and cosine theta vertical?
Homework Equations
All relevant equations are given.
The Attempt at a Solution
The solution is given.
Hi, I am having a seemingly hard time trying to find the tension in this rope. I've looked everywhere for a problem with these given variables but I found none. Here we are given: T1, T1 angle, mass of man and that is all. I included the picture here.The Attempt at a Solution
I found, t1y, which...
Homework Statement
The system is in equilibrium with the center string exactly horizontal. Find T1, T2, T3, and theta
Homework Equations
T1cos(angle1)-T2cos(angle2)=0
T1sin(angle1)+T2(angle2)-mass1=0
The Attempt at a Solution
Currently working on mass 1
When making free body diagrams for...
Homework Statement
Homework Equations
F=ma
The Attempt at a Solution
Does the total Force F=50N divide evenly between m1+m2 and m3? Meaning the tension between m1/m2 & m3 is 25N given m1+m2=m3. Also, is the acceleration between m1/m2 & m3 the same as the acceleration at m3...
Homework Statement
Three masses as shown below are resting on a horizontal, frictionless surface. The blocks are connected by massless, frictionless ropes. A force F of 60 N acts on the system as shown. Find the tensions in each of the other two ropes. m1= 10kg, m2 = 20 kg and m3 = 30 kg...
Homework Statement
Block "m1" sits on a horizontal frictionless surface. Block "m2" is hanging below the pulleys as shown. All of the pulleys are massless and frictionless. Given [m1, m2]. Determine:
a. The tension in each rope.
b. The acceleration of each block.
Homework Equations
Sum(F) =...
Homework Statement
A) Draw a free body
B) determine the tension in rope A and the reactions in B.
Homework Equations [/B]
Standard equilibrium equations
The Attempt at a Solution
My free body shows a collinear force T through the rope, the given downward force at 5ft, and then a Bx and By...
Homework Statement
A loop of flexible chain, of total weight W, rests on a smooth, frictionless right circular cone of base radius r and height h. The chain rests in a horizontal circle on the cone, whose axis is vertical. Find the tension in the chain.
Homework Equations
Virtual work, but...
Homework Statement
The steel beam is supported by cables AB and CD and a ball-and-socket joint at O. The position of the vertical point load, P influences the reaction at O as well as the tension in each cable.
First you need to derive the equations for the tension in cable AB, the tension in...
Homework Statement
17. Give the correct tension, T, in the marked rope for each situation. The rope is held so the system is stationary. All ropes and pulleys are massless and frictionless.
A) T = W B) T = W/2 C) T = W/3 D) T = 2W E) T = 3W/2
F) T = 2W/3 G) T = W/7 H) T = W/5...
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AP French Mechanics Problem 7-1
Two identical gliders, each of mass m, are being towed through the air in tandem. Initially they are traveling at a constant speed and the tension in the tow rope A is T(sub0). The tow plane then begins to accelerate with an acceleration A...
Homework Statement
Answer True, False, or Cannot tell to each of the five statements below.
A small projectile is launched horizontally 1 m above the surface of a smooth, airless planet, with sufficient speed for orbit. A bug riding in a small hole in the projectile has apparent weight...
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[/B]
Your niece finds her father's watch. The light watch chain has a length of 48 cm, and the mass of the watch is 270 g. Your niece swings the watch in a vertical circle, maintaining the speed of the watch at 2.3 m/s. Find the tension in the chain when it makes an angle of...
So my pulley system has 3 masses two of which are connected to a center mass on top of a table. No mass was given for any of the objects but of two masses hanging from the table, the one on the right is 2 times the mass on the left. I hope I haven't confused you but its like a three step diagram...
Homework Statement
Looking for the tension in cable Tcd when the moment on A is equal to 0.
P1 = 73N.
I’ve had several attempts but I can’t seem to obtain the answer, which is 110,8 N.
Can anyone help me with this question?
Homework EquationsThe Attempt at a Solution
Homework Statement
Chain of mass M hangs between 2 walls with its ends at the same height. The chain makes an angle θ with each wall. Find the tension at the lowest point of the chain.
a) By considering the forces on half of the chain.
b) By using the fact that the height of the chain is...
Homework Statement
At a latitude of 50° north a mass is hanged by a massless string. By the means of an angle how much does the mass deviate from the Earth's radius due to rotation of the earth? Consider the Earth as a spherical body.
Homework Equations
Fcp=mv^2/r
w=dθ/dt
v=wr
The Attempt at a...
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...
This was a problem on an exam that our professor later discovered was unsolvable THE WAY HE POSED THE QUESTION. First off, it's important to note that this is from a statics class, therefore Fnet = 0 will be true for all problems in our course.
So here's my thoughts on this and I would like to...
Homework Statement
[/B]
A sign with a mass of 27 kg is hanging in two wires both making an angle of 25 degrees with the vertical. Find the tension in one of the wires. Give your answer in Newtons (N) and with 3 significant figures.
Homework Equations
Ftens=gravity/sin(x) ?
The Attempt at a...
Homework Statement
A 1.26kg toaster is not plugged in. The coefficient of static friction between the toaster and a horizontal countertop is 0.395. To make the toaster start moving, you carelessly pull on its electric cord. For the cord tension to be as small as possible, you should pull at...
Homework Statement
A 65kg rock climber is abseiling down a rock, consider the situation when he's in equilibrium and standing at an angle on the surface of the rock, hanging from a rope.
The rope is at an angle of 40 degrees to the horizontal, calculate the tension in the rope
Homework...
Homework Statement
Look I have an exercise about trusses in vector mechanics. It's the following:
https://scontent-lax3-1.xx.fbcdn.net/hphotos-xfp1/v/t1.0-9/12003339_1645511085733429_8210043018491702007_n.jpg?oh=4955534403fb6f3f5f9a40c9c0b8ecbc&oe=569761ED
I have to determine the forces in...
Homework Statement
The diagram shows the instant when a long slender bar of mass 4.9 kg and length 4.9 m is horizontal. At this instant the mass m= 6.5 kg has a vertical velocity of 4.0 m/s.
If the pulley has negligible mass and all friction effects may be ignored, what is the magnitude of the...
In the figure we see two blocks connected by a string and tied to a wall, with θ = 33°. The mass of the lower block is m = 0.9 kg; the mass of the upper block is 4.0 kg. Find the tension in the string that is tied to the wall.
-I have the forces of Block A as Tension, Normal Force, and Gravity...
Homework Statement
I was asked to find the tension in CD in this question . The ans given is 4.22kN.
my working is arc tan (surd 13)/12, tetha = 16.7 degree
CD cos (16.7) = 20kN
CD= 21kN.
p/s: i have used pythagora's theorem to fe the surd 13
Homework EquationsThe Attempt at a Solution
Homework Statement
A railway engine of mass 100 tonnes is attached to a line of trucks of total mass 80 tonnes. Assuming there is no resistance to motion, find the tension in the coupling between the engine and the leading truck when the train: (a) has an acceleration of 0.020 ms-2, (b) is...
Two steel straps are use to hold member BCD level. The size of each strap is 12 mm thick and 50 mm wide. A 16 mm diameter bolt is used to connect thesteel straps to the 89 x 89 mm post at A. A 25 kN is applied at the free end of the cantilever at point D. Determine:
the tensile stress developed...
Homework Statement
A 10.0kg sphere is attached to the incline by a horizontal string. Determine the tension in the string.
Homework Equations
(F⃗ net)x=ΣFx=0
(F⃗ net)y=ΣFy=0
Στ=0
τ = (radial disance)(F)
The Attempt at a Solution
1. I began by determining all the relevant forces associated...
At one point I had been trying to construct an equation which would calculate the tension on a tuned string with a change in temperature (and therefore the fundamental frequency), but found my calculations were wrong. By extension, the purpose of the project was to be able to calculate what...
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. The tension in the string is measured at 0.200 N. What is the measure of angle θ?
Homework Equations
∑F=ma, a=v^2/r
The Attempt at a Solution
I broke down the forces at...
Homework Statement
A rope is used to lower a 1.1 kg bucket into a well at an acceleration of 1.9 m/s2. Determine the tension in the rope (in Newtons). Assume that air resistance is negligible and the acceleration due to gravity is -9.8 m/s2. Take the positive direction to be upward.
Homework...
Homework Statement
I attached a picture of the question.
Homework Equations
∑Fx=0
∑Fy=0
100kg(9.8)= 981 N
I am not sure how to start this problem. Everything else in this chapter is a breeze so perhaps a small insight or how to start would be sufficient, thanks.
Homework Statement
Three identical balls (of equal masses) are connected by light inextensible strings and kept on a smooth horizontal surface. The middle ball B is given a velocity ##v_0## at ##t=0##. Find the velocity of ball A when A collides with C.
Homework Equations
Impulse ##J=\Delta...
Homework Statement
A 15000-kg helicopter is lowering a 4000-kg truck by a cable of fixed length. The truck, helicopter, and cable are descending at 15.0 m/s and must be slowed to 5.00 m/s in the next 50.0 m of descent to prevent damaging the truck. Assume a constant rate of slowing.
Determine...
Homework Statement
How do you find tension and friction on an inclined plane given acceleration, two masses and an angle? It's a pulley system, I suppose.
Here's a diagram I drew:
http://postimg.org/image/m9v9i2qy5/
Homework Equations
Fg = ma
The Attempt at a Solution
I was thinking that I...
Homework Statement
A particle of mass m is whirled on the end of a string of length R. The motion is in vertical plane in Earth's gravitational field . The instantaneous speed is v when the string makes angle Ө with the horizontal. Find the tension T in the string and the tangential...
When a particle is attached to a rope and rotated, then tension acts perpendicular to displacement and work done is zero. But I am thinking about this case (top view):
Here, the rope is attached to a vertical cylinder and the particle is given a velocity perpendicular to the rope. The length...
I drew a FBD about point A and came up with the two equations:
∑Fx=0 20sinθ - T-ab(cos70)=0
ΣFy =0 -20cosθ + T-ab(sin70) -20=0
My answer is not coming out so I either messed up on the FBD or the equations, some help would be appreciated. I'm on 3-10 by the way.
Homework Statement
An empty elevator of mass 2.7×103 kg is going down by a cable at an acceleration of 1.2 m/s2. What is the tension in the rope pulling the lift?
Homework Equations
## T=m(g-a) ##
The Attempt at a Solution
## T=m(g-a) \\ \Rightarrow T = 2.7 *10^3 (9.8-1.2) \\ \Rightarrow T=...
Homework Statement
Use the principle of moments and take moments about A to show that the weight of the object O is 19 N.Homework Equations
Moment=Force x perpendicular distance
The Attempt at a Solution
Vertical component of tension= TsinA...
Homework Statement
A match of length l=4cm is floating on the surface of the water from a glass. ( the water is at room temperature) If from on one side of the match we pour a few drops of soap, the match starts moving. In which direction is the match mooving and what force is acting upon it? (...
Hi All,
I'm confused with a particular question and I'm not entirely sure how the answer was derived.
A one-meter board with uniform density hangs in static equilibrium from a rope with tension T--The rope is connected .2m from the left end. A weight of 3kg hangs from the left end of the...
A heavy board is fixed to another flat surface along its entire upper edge and not moving. How can I find the tension force that is acting on the board? Is it the same as if the board would be fixed to a string in the middle of the upper edge and hung and then the tension would be T=mg?
Homework Statement
A homogeneous flexible rope rests on a wedge whose sides make angles α and β with horizontal. The centre of rope lies on C. With what acceleration should the wedge be moved for the rope to stay stationary with respect to wedge? (all surfaces are smooth).
Homework Equations...
Suppose a pulley is lifting a mass through rope so the rope is applying force to mass in form of Tension. Is the rope also applying that force to pulley i.e Is pulley being acted upon by Tension??
1. Homework Statement
The tension in the cable is 800LBs. Find the depth of water that produces this tension. The gate is hinged at B; the cable is attached at A. (Figure 1)Homework EquationsThe Attempt at a Solution
OK, so this is just 2 opposing lever arms: the tension in the cable is...
Homework Statement
A plate is fixed to the ceiling by two wires and to the wall by a single wire.
The wall wire is cut. Calculate the tension in the two remaining wires.
mass = 800 kg
g = 10m/s²
Dimensions in sketch
Homework EquationsThe Attempt at a Solution
Equations:
Ra*cos30 + Rb*cos30 =...
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...