What is Static equilibrium: Definition and 357 Discussions
In classical mechanics, a particle is in mechanical equilibrium if the net force on that particle is zero. By extension, a physical system made up of many parts is in mechanical equilibrium if the net force on each of its individual parts is zero.In addition to defining mechanical equilibrium in terms of force, there are many alternative definitions for mechanical equilibrium which are all mathematically equivalent. In terms of momentum, a system is in equilibrium if the momentum of its parts is all constant. In terms of velocity, the system is in equilibrium if velocity is constant. In a rotational mechanical equilibrium the angular momentum of the object is conserved and the net torque is zero. More generally in conservative systems, equilibrium is established at a point in configuration space where the gradient of the potential energy with respect to the generalized coordinates is zero.
If a particle in equilibrium has zero velocity, that particle is in static equilibrium. Since all particles in equilibrium have constant velocity, it is always possible to find an inertial reference frame in which the particle is stationary with respect to the frame.
Homework Statement
In Figure 12-36, horizontal scaffold 2, with uniform mass m2 = 35 kg and length L2 = 2.0 m, hangs from horizontal scaffold 1, with uniform mass m1 = 45 kg. A 17 kg box of nails lies on scaffold 2, centered at distance d = 0.50 m from the left end.
What is the tension T in...
A 1.2 kg board 2.0 m long is pivoted exactly at its center. A 2.0 kg box is at one extreme end. For the board to remain balanced, a 5.6 kg box should be placed how far away from the other end
Homework Equations
mass1(.5)(2.0)= mass2 (d)
The Attempt at a Solution
.357 meters
Homework Statement
A 75 kg window cleaner uses a 10 kg ladder that is 5.0 m long. He places one end on the
ground 2.5 m from a a wall, rests the upper end against a cracked window and climbs the ladder. He is 3m up along the ladder when the window breaks. Neglect friction between the ladder and...
Homework Statement
A 15.5 m uniform ladder weighing 500 N rests against a frictionless wall. The ladder makes a 56.0° angle with the horizontal.
(a) Find the horizontal and vertical forces the ground exerts on the base of the ladder when an 810 N firefighter is 4.10 m from the bottom...
Homework Statement
A window cleaner of mass 95 kg places a 22kg ladder against a frictionless wall at a angle 65 degrees with the horizontal. The ladder is 10 m long and rests on a wet floor with a coefficient of static friction equal to .40. What is the max length that the window cleaner can...
Homework Statement
A climber with a weight of 510 N is held by a belay rope connected to her climbing harness and belay device; the force of the rope on her has a line of action through her center of mass.The indicated angles are θ = 41˚ and φ = 26˚. If her feet are on the verge of sliding...
Hey all, new member here
Homework Statement
Two uniform 75g marbles 2cm in diameter are stacked on top of each other in a container that is 3cm wide
the top marble touches right side of the container, the bottom touches the left side.
Point A is the bottom marble left contact point with the...
Homework Statement
Mountaineers often use a rope to lower themselves down the face of a cliff (this is called rappelling). They do this with their body nearly horizontal and their feet pushing against the cliff (the figure (Intro 1 figure) ). Suppose that an 84.7-{\rm kg} climber, who is...
Homework Statement
Blocks A and B weigh 400 and 200 kN, respectively. They rest on a 30degrees inclined plane and are attached to a post hinged at O by cords parallel to the plane, as shown in Fig. E06-1.3. The post is held perpendicular to the plane by force P. Assume that all surfaces are...
Homework Statement
The figure shows an outstretched arm with a mass (m1) of 4.4 kg. The arm is 56 cm long, and its center of gravity is 21 cm from the shoulder. The hand at the end of the arm holds a 6.0-kg mass (m2). (so its a man holding a dumbell, and his arm is 15 degrees up from the...
Homework Statement
http://www.physics.upenn.edu/~jrk/p101/Homework/hw7_sp09.pdf
Here is the link. I am having trouble with questions 8 and 9. I posted the whole link because these questions have a diagram that go with it.
Homework Equations
Sum of F = 0
Sum of torque=0
The...
Homework Statement
A traffic light hangs from a pole as shown in the figure (Intro 1 figure, see link: http://session.masteringphysics.com/problemAsset/1058163/3/GIANCOLI.ch12.p21.jpg" ) . The uniform aluminum pole AB is 7.20 m long and has a mass of 11.0 kg. The mass of the traffic light is...
Homework Statement
A quarry crane is used to lift massive rocks from a quarry pit. Consider the simplified model of such a crane shown in the figure. The ends of two poles are anchored to the ground at the same point (point O). From this point, one pole rises vertically and the second pole...
Homework Statement
A horizontal scaffold 2, with uniform mass m2 = 30 kg and length L2 = 2.4 m, hangs from horizontal scaffold 1, with uniform mass m1 = 53 kg. A 21 kg box of nails lies on scaffold 2, centered at distance d = 0.45 m from the left end, which is located from 0.45 m from the left...
Homework Statement
Three forces are applied to a tree sapling to stabilize it. F1= 310 N and F2= 425 N
The forces are 110 degrees apart, solve for the magnitude and direction of the third force applied
Homework Equations
perhaps law of sine/cosine , this is really just solving for...
Homework Statement
A uniform 0.122 kg rod of 0.90 m length is used to suspend two masses as shown.
At what distance x should the 0.20 kg mass be placed to achieve static equilibrium?
2. The attempt at a solution
F1=1.96N
F2=4.9N
torque = 4.9 x 0.25 = 1.225 Nm.cw
1.23 =...
Static equilibrium!
Homework Statement
A 25-ft crane supported at its lower end by a pin is elevated by a horizontal cable as shown in the figure. A 250-pound load is suspended from the outer end of the crane. The center of gravity of the crane is 10 feet from the pin, and the crane weighs...
Homework Statement
One end of a uniform 4.00-m-long rod of weight Fg is supported by a cable. The other end rests against the wall, where it is held by friction, as in Figure below. The coefficient of static friction between the wall and the rod is s = 0.500. Determine the minimum distance...
Homework Statement
(a) Calculate the magnitude of the force, FM, required of the "deltoid" muscle to hold up the outstretched arm shown in the figure. The total mass of the arm is 3.3 kg.
(b) Calculate the magnitude of the force FJ exerted by the shoulder joint on the upper arm...
Homework Statement
Calculate the magnitude of the force, FM, required of the "deltoid" muscle to hold up the outstretched arm shown in the figure. The total mass of the arm is 3.3 kg. Then, calculate the magnitude of the force FJ exerted by the shoulder joint on the upper arm...
Homework Statement
Three forces are applied to a tree sapling, as shown in the figure, to stabilize it. If vector F A = 380 N and vector F B = 260 N, find vector F C in magnitude and direction.
http://www.webassign.net/gianpse4/12-45.gif
Homework Equations
The Attempt at a...
Homework Statement
A uniform beam of length 1.0m and mass 10 kg is attached to a wall by a cable (the cable makes a 30 degree angle with the beam). The beam is free to pivot at the point where it attaches to the wall. What is the tension in the cable?
Homework Equations
F(net) = F(beam)...
Homework Statement
A boy carries a sack on one end of a very light stick that is balanced on his shoulder, at an angle of 22.0 degrees up from the horizontal. The mass of the sack is 7.00 kg, and it sits 1.20 m from his shoulder. If his hand is 0.350 m from his shoulder, on the other end of...
im working on an experiment about static equilibrium and i need help with number 3 on the calculations and analysis
1. how do you find the horizontal and vertical % of F4?
2. how do you make a graph out of the vectors found under the procedures section?
3. how do you find the residual from...
Homework Statement
Three ropes are tied together. One of your friends pulls on a rope with 3.0 units of force and another pulls on a second rope with 5.0 units of force. Friend Two is 120 degrees to the left of Friend One (where Friend One's vector is on the positive x-axis).
Homework...
A window cleaner of mass 95 Kg places a 22 KG ladder against a frictionless wall, at an angle 65 degrees with the horizontal. The ladder is 10 m long and rests on a wet floor with a coefficient of static friction equal to 0.40 What is the maximum length that the window cleaner can climb before...
You have been called on to testify in a product liability lawsuit. An infant sitting in a portable seat that is supported by the edge of a table fell to the floor (see the figure). The manufacturer claims the child was too heavy for the seat, and the parents claim the seat was defective. Testing...
The figure shows a wheel on a slope with inclination angle 16 degrees, where the coefficient of friction is adequate to prevent the wheel from slipping; however, it might still roll. The wheel is a uniform disk of mass 1.35 kg, and it is weighted at one point on the rim with an additional 0.960...
Homework Statement
A uniform board of length L and weight W is suspended between two vertical walls by ropes of length L/2 each. When a weight w is placed on the left end of the board, it assumes the configuration shown in the figure.
http://img260.imageshack.us/img260/3992/rw1234ok6.jpg...
I don't like writing formulas on the computer, so i just scanned my attempt.
http://c.imagehost.org/view/0630/q.jpg
In my working out, i incorrectly use the mass of 21kg for the light, it's actually 21.5kg...but either way my working out is still incorrect.
Thanks in advance, Frantelle.
Homework Statement
A man doing push-ups pauses in the position shown (in the figure I found on the net)
a= 40cm b= 95cm c= 30cm Tha mass of the person is 75kg. Determine the normal force exerted by the floor on each hand and each foot.
Homework Equations
\Sigma\tau=0
\SigmaF=0
The...
How do you know when to use the sum of all forces acting on a body compared to the sum of all tourques acting on a body when solving for these types of questions involving ladders, hanging signs, etc...
STATIC EQUILIBRIUM question help please!
Homework Statement
A 50 kg high wire artist carries a weighted pole, as illustrated. Her center of gravity is 80cm above the high wire, and the two 23 kg masses are located 120 cm vertically below the wire. Find the vertical location of the centre of...
Homework Statement
A meter stick balances horizontally on a knife-edge at the 50.0 cm mark. With two 5.0 g stacked over the 12.0 cm mark, the stick is found to balance at the 45.5 cm mark. What is the mass of the meter stick?
Homework Equations
netF = 0
netTorque = 0
The answer is...
A string that passes over a pulley has a .301kg mass attached to one end and a 0.635 kg mass attached to the other end. The pulley, which is a disk of radius 9.50cm, has friction in its axle. What is the magnitude of the frictional torque that must be exerted by the axle if the system is to be...
Homework Statement
In fig. 13-32, a 50.0 kg uniform square sign, 2.00 m on a side, is hung from a 3.00 m horizantal rod of negligible mass. A cable is attached to the end of the rod and to a point on the wall 4.00 m above the point where the rod is hinged to the wall. (a) What is the...
Homework Statement
An object of mass m= 5.0g and charge Q= 45mC is attached to a string and placed in a uniform electric field that is inclined at an angle of 30.0 with the horizontal (see the figure). The object is in static equilibrium when the string is horizontal
Homework...
Homework Statement
An automobile with a mass of 1360 kg has 3.05 m between the front and rear axles. Its center of gravity is located 1.78 m behind the front axle. With the automobile on level ground, determine the magnitude of the force from the ground on a) each wheel (assuming equal...
Homework Statement
Two point charges q and 4q are distance L apart and free to move. A third charge is placed so that the entire three-charge system is in static equilibrium.
Homework Equations
\SigmaF=0 This is the equation for static equilibrium
\vec{E}=q/4\pi\epsilon_{0}r^2
The...
Homework Statement
Four blocks with masses 2kg, 4kg, 6kg, 3kg are held together with ropes with tensions Tx, Ty, Tz. There is a force of 20N pointing to the right and 50N to the left. Find Tz.
Homework Equations
The Attempt at a Solution
This is like the static equilibrium...
Homework Statement
IT IS POSTED IN THE ATTACHMENT BELOW
Homework Equations
everything is in static equilibrium
The Attempt at a Solution
well I know how to follow up to solution on these types of problems quite easily, however..on this one I can't seem to get started because I...
We put a 100 cm ruler on a table at the 50cm mark. The 0cm mark is on the table and the 100cm mark is in free air. The ruler is in static equilibrium.
Now we place the ruler on the table at the 40cm mark, creating a torque on the ruler so that it is not balanced.
Next attach a weightless...
We put a 100 cm ruler on a table at the 50cm mark. The 0cm mark is on the table and the 100cm mark is in free air. The ruler is in static equilibrium.
Now we place the ruler on the table at the 40cm mark, creating a torque on the ruler so that it is not balanced.
Next attach a weightless...
A cylindrical container 1.2 m tall contains mercury to a certain depth, d. The rest of the cylinder is filled with water. If the pressure at the bottom of the cylinder is 1.9 atm, what is the depth d?
Does anyone have any ideas on how to approach this problem, better yet,solve it!?
A non-uniform bar of weight W = 12.5 N is suspended at rest in a horizontal position by two massless cords. The angle φ between cord 2 and the vertical is equal to 27.5°. The bar has a length L = 6.0 m and the distance of its center of gravity from the left-hand end of the bar is 4.4 m. What is...
Homework Statement
An acrobat hangs by his hands from the middle of a tightly strestched horizontal wire so that the angle between the wire and the horizontal is 9.15 degrees. If the acrobat's mass is 88.4kg, what is the tension in the wire? Answer in units of N.
Homework Equations
Sum...
Homework Statement
A 0.105 kg meter stick is supported at its
40 cm mark by a string attached to the ceiling.
A 0.665 kg object hangs vertically from the
7.17 cm mark. A second mass is attached
at another mark to keep it horizontal and in
rotational and translational equilibrium.
If...
Please help with this question. I don't know how to approach this difficult question
a crossing guard holds a STOP sign at arm's length, as shown. Her arm is horizontal, and we assume that the deltoid muscle is the only muscle supporting her arm. The wright of her upper arm is Wu = 18 N, the...
Homework Statement
A 6.3-m long plank is supported by two concrete blocks, one that is placed 2 m from the left end of the plank and another that is placed 1.2 m from the right end. The mass of the plank is 44.5 kg.
(a) Find the normal force from each of the concrete blocks on the plank...