Tagged Questions
6
votes
3answers
135 views
Where does the extra equation come from to determine the forces from an object on a table?
I have a question about basic statics but somehow I cannot manage to find the answer on my own (btw, this is not a homework. It's been so many years since school for me...).
The problem is very ...
0
votes
0answers
21 views
The stress in copper and steel parallel compound members [closed]
Came across this question and just needed abit of help undertanding how i should go about this question
I have also attempted to solve it to the best of my ability but im stuck.
A concrete column of ...
2
votes
1answer
85 views
Statics of Rigid Bodies — Can there be two possible solutions?
I've been working on a question and there seem to be two possible solutions. My own solution does not match the one given in the book. However, after resolving forces and taking moments with both ...
3
votes
3answers
88 views
Does a cross really have a smaller area moment of inertia than a square of the same area?
I need to calculate the area moment of inertia of a cross for a homework assignment. The cross is a symmetric plus sign:
_
| |
|== ==|
| |
-
...
0
votes
1answer
92 views
Problem solving moments in equilibrium
Two straight ladders, AC and BC, have equal weights $W$. They stand in equilibrium with their feet, A and B, on rough horizontal ground and their tops freely hinged at C. Angle CAB = 60$ ^o$, angle ...
4
votes
1answer
88 views
Application of Archimedes Principle
A candle is floating in a liquid placed in a container. The container is a cylinder of diameter $D$, and the candle is of width $d$. ($D>d$) The height of the liquid from the bottom of the ...
0
votes
1answer
33 views
Find the bending moment of a pole attached to a moving block
I'm having trouble with the following problem.
What I've done so far:
x-y is the usual coordinate system.
$a=\frac{F}{m}=\frac{800}{60}$ and the y component of this is $a_y=a\sin{60^\circ}$.
To ...
0
votes
0answers
73 views
Tension $T$ in cable [closed]
Calculate the tension $T$ in each cable, as well as the magnitude and direction of the force exerted on the strut by the pivot in each case mostrados.En systems, w is the weight of the suspended box, ...
1
vote
1answer
144 views
Cylinder rolling down an inclined plane held by a string
A cylinder of mass M and radius R is in static equilibrium as shown in the diagram. The cylinder
rests on an inclined plane making an angle with the horizontal and is held by a horizontal string
...
1
vote
1answer
77 views
Force analysis on truss
I am reading a book on fundamental physics for mechanics. There is a truss shown in the figure. A train of mass $M=56$ ton is resting at the middle point of AC, ignore all the mass of truss and rails. ...
0
votes
1answer
56 views
Statics Moment Diagram
I am having troubles converting my shear diagram into a moment diagram. Either I am doing something wrong or MasteringEngineering is incorrectly marking it wrong. Anyway here is the problem/correct ...
5
votes
3answers
227 views
Force between two charged rods?
Suppose that we have two rods of length $l_1, l_2$ connected at one end but free to rotate. These rods have charge density $\lambda$ uniformly distributed, so the total charge of rod $i$ is $\lambda ...
0
votes
0answers
27 views
How do I minimize the the stress created by fore-aft forces?
My friends and I are designing a bench press spotter. Essentially, when the user needs help lifting the barbell due to muscle fatigue, an arm on each side of the user raises to provide assistance. ...
1
vote
2answers
102 views
Additional mass of block on inclined plane
I would like some help in solving this problem.
Height is 15 cm , base is 88 cm
My attempt:
$$(119.3 + m)(\sin(\theta)) = (88*9.8)$$
$$ 15^2 + 88^2 = 89.269^2 $$
$$ \sin^{-1} = 15/89.269 $$
$$ ...
0
votes
0answers
151 views
How to solve fixed-fixed beam with finite difference method?
What equations to use on this system to form a matrix $A$ with dimensions $[n,n]$ and load vector $q$ with dimension $[n]$ ? I am trying to get vertical displacement $w$.
$$w = A^{-1}\times q$$
...
1
vote
0answers
55 views
How can I calculate all of the tensions in the cords? [closed]
I have been stuck on this problem for the last half, and to be honest I don't even no where to begin. I'm being asked to calculate all of tensions for the cords. I know I'm supposed to use $\cos$ to ...
3
votes
0answers
177 views
Shape of a string/chain/cable/rope?
The height of a string in a gravitational field in 2-dimensions is bounded by $h(x_0)=h(x_l)=0$ (nails in the wall) and also $\int_0^l ds= l$. ($h(0)=h(l)=0$, if you take $h$ as a function of arc ...
0
votes
3answers
135 views
Doubts with levers
I'm studying for a test of static rigid body and I'm having doubts on how to solve problems involving levers with weight.
If I have, for example, a lever 10 kilograms and 3 meters long and one support ...
1
vote
1answer
442 views
Solving a Statically Indeterminate Truss with Energy Equations (Tricky)
Okay, first off, I know that there is a very similar problem about statically indeterminate trusses here, but my problem was a bit different and I didn't know how to adapt the answer for that problem ...
0
votes
1answer
644 views
How to calculate the supporting force for a cantilever beam? [closed]
How do I find the supporting force $R_A$ and the moment $M_A$?
Should I use the sum of moments or?
0
votes
1answer
213 views
Can I use Newton's second law to solve what seems to be a torque problem?
The Problem:
An 8-m-long beam, weighing 14,700 N, is hinged to a wall and supported by a
light rope that is attached 2.0 m from the free end of the beam. If the beam is
supported at an angle ...
4
votes
1answer
749 views
Solving a statically indeterminate truss
I'm trying to solve the statically indeterminate truss shown below and I'm having a little trouble.
$H$, $P$ and $\beta$ are given. The material is aluminum (density is 2700 ${kg/m^3}$) and has a ...
0
votes
1answer
140 views
Relationship between torques and centre of mass or centre of gravity [closed]
1) A wardrobe is $2$m high and $1.6$m wide. When empty, it has a mass of $110$kg and its centre of gravity is $0.8$m above the centre of its base. What is the minimum angle through which it must be ...
1
vote
1answer
61 views
Force in tetrahedron edges
I am looking for a formula that enables me to calculate the force in a tetrahedron edge such that it relates $F_b$ with $F_z$ through the beam thickness and length. I have the following assumptions:
...
-1
votes
1answer
262 views
Internal forces in a truss and its geometry
I'm to work out the internal forces in a truss, but I can't get my head around the geometry of the truss itself. I'm starting to think there may have been information on the diagram which I missed. ...
0
votes
1answer
327 views
Calculating torque in a structure
I posted this on math stack exchange but realize it is more a physics question.
I have a structure which is set up as shown in the image. A weight hangs from point A with mass $m$. Joint B is free ...
0
votes
1answer
290 views
Hinged bridge statics problem
For part (a), is the normal force by the hinge on the bridge at an angle or is it horizontal?
For part (b), I know how to resolve forces horizontally and vertically, and to take torques about the ...
1
vote
1answer
450 views
Calculating mass of object by lifting edge
Assuming a solid rectangular plate, hinged along one edge. How does one calculate the mass of the plate if the force necessary to lift the opposite edge is known?
1
vote
1answer
290 views
Problem in a truss [closed]
For the truss above known are the following: l= 1 + 0.02*n [m], h = 2 + 0.01*n [m], F_1 = 200 + 2*n [N], F_2= 500 + 6*n [N], F3 = 400 + 5*n [N], Young's modulus E = 2*10^11 [N/m2], allowable stress ...
0
votes
1answer
362 views
Can anyone solve this simple static equilibrium problem? [closed]
A bridge is 50m long, has a mass of 20,000kg, and rests on two pivots, A and B. The distance between A and the left side of the bridge is 10m. The distance between B and the right side of the bridge ...
-1
votes
1answer
122 views
Find largest angle
The two homogeneous bars AB and BC are connected with a pin at B and
placed between rough vertical walls. If the coefficient of static friction between
each bar and the wall is 0.4, determine the ...
1
vote
1answer
130 views
Finding the contact force in a mechanical problem [closed]
what is the proper FBD for this system. I cant decide since the weight is given, but there is tension and contact forces. Things get mixed up.
Determine the contact force between the smooth 200-lb ...
0
votes
2answers
1k views
How do I find the tension in additional strings in this problem?
A mass of 5.00 kg hangs attached to three strings as shown in the figure (see image below). Find the tension in each string. Hint: Consider the equilibrium of the point where the strings join.
...
0
votes
1answer
446 views
Solving an indeterminate triangle truss structure (statics)
From the setup of two trusses as shown in this illustration, how can I solve for the axial reaction forces in the trusses, and in the points A and B (Ax, Ay, Bx, By)? It is assumed that the joints ...
4
votes
1answer
513 views
Hooke's Law question
I have the following question to answer:
a force of160 N stretches a spring 0.050m from its equilibrium position.
A. what is the spring constant of the spring?
The equation for Hooke's Law in my ...
0
votes
0answers
632 views
Calculating weight using moments [A-Level] [closed]
A uniform plank of weight 150N and of length 4.0m rests horizontally on two bricks. One
of the bricks is at the end of the beam. The other brick is 1.0m from the other end of
the plank.
a) Sketch the ...
1
vote
2answers
291 views
How do you choose the locations of forces when calculating moments?
A uniform bridge of weight 1200kN and of length 17m rests on supports at each end which are 1m wide. A stationary lorry of weight 60kN has it’s centre of mass 3.0m from the centre of the bridge.
...
0
votes
1answer
996 views
Moment calculation [closed]
Consider image below. The weight of the fire-fighter is 840 N. What is the torque of the fire-fighter's weight about P and what is the value of the force C which cancels out the torque?
