Questions tagged [applied-mechanics]

Questions about using applied mechanics to model engineering problems.

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1answer
106 views

Why is the Stress vs strain diagram preferable to the Load vs displacement diagram?

I’m really unsure what is the difference between stress vs. strain and load vs displacement graphs and why stress-strain is better. I know that the units are different: stress is in MPa and the load ...
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2answers
37 views

Condition for equilibrium of a rigid body on a horizontal surface

The following question is from a past paper from Further Mechanics and it has been bothering me immensely I have spent hours cracking at a way to make sense of it, the question is in two parts Part ...
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0answers
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Sprocket Angular Velocity [duplicate]

I have a question please that I need help on. Consider the chain that is draped over the sprocket with mass moment of inertia of 0.005kgm^2 about central axis. If 4kg block is released from rest from ...
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30 views

Are there examples of spring-mass-damper system that exhibit increasing growth in an unstable way

Simply, are there examples of spring-mass-damper systems that exhibit unbounded behavior or at least increasing behavior for a period of time. I am trying to do some vibrations research, but I am ...
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3answers
132 views

Force and the reactions on the supports

Consider the movement in the vertical plane of an $AB$ bar with a mass of $20 kg$, $0.8 m$ long and supported by two cursors: one at the end A and the other at point G coinciding with the center of ...
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1answer
32 views

Want to simulate a mechanism with spring in it for forces acting in different direction (Kinematics). How to do it using solidworks or ANSYS? [closed]

Thought of using motion study in Solidworks but not able to account for forces at the different axis in it here is the image to better understand it. There hasn't been any progress with the ...
2
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1answer
64 views

To stop or to go around?

Let us we are moving in a car. There is a wall in front of us, we need to decide can we go around it or not. It is known that width of the wall is $w$ and our speed is $v = const$. What is a simple ...
3
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1answer
64 views

Determine the aceleration of points B,C and D, angular aceleration of rod and the tension in rope DE when ropes AB suddenly breaks

The solutions are F(DE)=134.38N, a(D)=2.016m/s^2 , α=1.29rad/s^2, a(C)=7.828m/s^2 I agree that the FBD and the KD are these: Then to solve this problem I've done: $$\sum M_{c}= I \alpha_{BCD}$$ $<=...
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1answer
36 views

Why this torque is not considered into the virtual work principle equation?

In the picture above you can see a SCARA robot, with its end effector (the point x,y). The torques c_a and c_b are the ones of the motors in the joints, while f is an external force. My teacher has ...
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3answers
73 views

How to solve this Question regarding compound accelerations

So , I was trying to solve it. Then , I notice that acc of 2kg mass has 2effects. One acc from the force to left and one from the Question , it says acceleration to be up. Then , the 2kg mass would go ...
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1answer
97 views

Determine the angular velocity and angular acceleration of the AB bar at the instant shown

Consider a sliding cursor C that is fixed to the disk which has a constant angular velocity counterclockwise at 4 rad/s. Determine the angular velocity and angular acceleration of the AB bar at the ...
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3answers
62 views

Different results when applying equation

The system shown in the Figure is guided by two blocks in A and B, that move in the fixed grooves. If the speed of A is 2m/s down, determine the speed of B at time θ = 45º In the textbook they said w ...
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3answers
58 views

In circular motion , why do we say this is centripetal acceleration

Let us say a particle is moving in a circle with Uniform circular motion . Then , if I take an equation like this . $\theta$ = S(Arc length or Total distance covered ) / Radius of circle *( time ...
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0answers
38 views

What is the purpose of the ink delivery disks found in most rollerball pens

See picture. In most rollerball pens there are those peculiar looking disks near the nib, the purpose of which I have not yet figured out, apart from being some kind of ink reservoir/flow control. ...
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2answers
47 views

Torque required to start rotating a wheel about its center

Assuming i have a circular disc of a significant mass and diameter. Neglecting friction, if a motor is put at its center how do i calculate the torque required for the wheel to just start to rotate? ...
0
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1answer
41 views

How to calculate torque required to rotate assembly about the center

The image is a hollow cylinder: 2in OD, 1.76in ID. Connected is an angled bracket, 45 deg, that weighs 3lbs. The top rectangle piece connected to the bracket is 10 lbs,the dimensions are 31.1in x 14....
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2answers
30 views

Is dimension of angular displacement never degree?

Is units of angular displacement never a degree and is always a radian ?
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2answers
36 views

Did not understand this regarding angular velocity

It says $V\sin \alpha$ (component of velocity perpendicular to OP) is the cause of angular displacement. How is it? if only $V\cos \alpha$ existed, we need not turn over head to always to look at a ...
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0answers
35 views

Gear/Mechanics problem: How to design to allow for 2 types of rotation

I am designing a new mowing system that can effectively mow around poles. The machine consists of an arm that is attached to the back of a tractor and runs off its PTO. At the end of the arm is a ...
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1answer
22 views

Why are the two acceleration considered as a1 and a2 here and find acceleration of 6kg mass?

Why are the two acceleration considered as a1 and a2 here? What is the reason for this even though the tension of both the strings are same. T is equal to 5gTcos 53 for left side and 5gTcos37 for the ...
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0answers
70 views

Calculating the bending moment ($M$) of a beam as it relates to stress ($σ$) and strain ($ε$)?

I am trying to learn how to work out the bending moment for progressively complex systems to model a beam. I am assuming only one axis of motion (transverse = $y$). For the basic equations of motion, $...
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1answer
104 views

Determine the reactions on supports A and C and write the functions of the internal forces for the beam sections AB

The figure shows a metallic structure composed of two beams $AB$ and $BC$ connected to each other by a pin in $B$, the structure being supported in A and C through fixed supports. In the AB beam, a ...
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1answer
40 views

Reinforce foldable table legs

I'm trying to build a table with 4 swivel legs that can be locked into arbitrary angles so that it can stand over one to three rows of storage crates in my garage: As you can see, the legs aren't ...
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2answers
88 views

formula for M(x) - Shear Force and Bending Moment Diagrams

I've watched the video "Understanding Shear Force and Bending Moment Diagrams" from "The efficient engineer" and i got a doubt in this exercise For $4<x<7$ I arrive to $V=-6x+...
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2answers
46 views

How to calculate the force required to lift this deck?

I want to build a folding deck. both sides are on wheels. Trying to wind my head around how to calculate the required force for the hydraulic piston to be able to pull the deck into a folded position.....
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1answer
224 views

How to mechanically attach a compression spring to a flat surface

I am working on a new project right now and I was wondering if anyone had any ideas on how to keep a spring fixed and connected to this flat plastic piece [image shown below]. Our goal is to keep the ...
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1answer
26 views

How could an absorbent material be emptied?

I have been thinking about this for quite some time: Given a foam or other absorbent material saturated with a solvent, how could you draw all the solvent to the top of the foam (basically how could ...
2
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1answer
43 views

Calculate thickness of a 1 square meter window made of acrylic in a submarine to endure 100meters

This question would have two parts: 1 - How to calculate thickness of a 1 square meter window made of acrylic in a submarine to endure 100meters of deepness in salt water? I don't remember the ...
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0answers
24 views

Pully size, imagine 2 systems A,B both transmitting power, both 1:1 but if OD of pulley is 50mm on A and 100mm on B, How do we choose optimal size?

All searches resulted in ratio calculations, which makes sense, my question relates to creating a servo driven spindle with 1:1 ratio with timing belt. Is increased belt surface engagement important ...
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2answers
110 views

How high will a flywheel catapult launch a payload?

First off, this is not a homework question or anything like that. I'm trying to build a catapult to launch a payload using a flywheel as an energy device! It goes like this: The flywheel spins up to ...
3
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2answers
67 views

Can you use an accelerometer to measure beam deflection under static loading?

With an appropriately collocated accelerometer is it possible to retrieve lateral deflection of a beam under static loading. The beam will be loaded and then deflect until it reaches equilibrium with ...
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25 views

how to obtain solution of this bessel equation using Frobenius method

Given this equation: $$ \frac{1}{r}\frac{d}{dr}\bigg(r \frac{dT}{dr} \bigg) - \bigg(\frac{2h}{bk} \bigg)(T-T_a) = 0 $$ I can let $x=r\sqrt{(2h/bk)}$ and $z=T-T_a$ to obtain the bessel equation using ...
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1answer
30 views

Pressure-force limiting blocks or relief mechanism for avoiding excessive pressure over a piece

I am looking for some device that can be used for blocking a sheet of glass or other materials in position. On one side of the glass (blue sheet in the diagram) is applied a force if the force is ...
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1answer
48 views

Deriving equation of motion of a 1 degree of freedom system

Before solving this system, note that the rigid bars $\mathrm{\overline{OA}}$ and $\mathrm{\overline{OB}}$ are rotating about point $\mathrm{O}$, not their respective CGs. To account for this two ...
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0answers
45 views

Why funnelling air in order to increase the velocity is a bad idea when generating power

Disclaimer: I’m not trying to violate the conservation of energy here; I know that’s impossible for us mortals. I think I’m either wrong or not considering something, I just want someone to point it ...
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1answer
51 views

Differential Equation for: Locking a laser's frequency with a PI controller

I think I have a good understanding of differential equations, so I would like to first try to understand my system in terms of differential equations before transforming my system into the more ...
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2answers
132 views

Does a change in specimen dimension affect the measured yield strength and tensile strength?

I am having a hard time trying to understand the effect of geometry on a specimen's yield and tensile strength or if there even is one. If there is an effect or not, why is it so? Thanks in advanced!
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1answer
114 views

Would this air amplifier attachment increase a leaf blower's effectiveness?

With the start of the leaf raking/blowing season just a month away, I have been thinking of a way in which I could make my old leaf blower more effective so I can spend less time doing leaf blowing. I ...
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1answer
51 views

What theories solve the problem of weight dispersion to minimize damage?

I assume there's some simple link to give me to answer this, but I don't know the terminology for it and so haven't been able to solve this. The use case it to avoid having my TV put divots into my ...
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5answers
2k views

Would a centrifugal flyweight governor system slow down the descent of an object that is free falling down to the Earth's surface? (Revised design) [closed]

I am wondering if rotating flyweights would slow down the descent of a object that is free falling down to the Earth's surface. Please reference the conceptual drawing below: This drawing is showing ...
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3answers
95 views

Torque required to rotate object around axis using Stepper Motor for Kinetic Machine

Hey all, I'm creating a machine to rotate a socket wrench using an arm attached to a motor shaft in order to make clicking sounds from the object therefore I'm trying to choose an appropriate stepper ...
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1answer
54 views

What causes an inflated spherical cap to look more like a mountain?

I'm working with bulge tests of materials using biaxial loading (applying pressure from one side through a circular aperture). The materials are clamped on the edges. The diameter of the aperture is &...
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0answers
30 views

Is a pyramid considered axisymmetric? Why so?

I read a source, I will not reference the source on this platform. They stated a pyramid is axisymmetric. Can you explain why if yes?
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1answer
51 views

Is there a way to convert a short throw in one direction into a long throw in two directions

I have a motor that I have created a simple adapter for; this lets us attach any parts we might design to solve the final problem: I would like to convert the motors motion to oscillating motion in ...
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2answers
34 views

How to design internal wall separation in the PVC tube to use it as a water tanker

I am working on design of the column which contains the water tanker and the pump + electronics at the bottom. I have tried different solutions and they failed. I would like to know your advice on ...
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0answers
19 views

Deformation gradient tensor from particle displacements in an inflating material

I don't have a mechanics background, but am trying very hard to read and understand how to approach this problem. I am struggling with understanding what's "correct" or the basic process of going from ...
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2answers
97 views

Fixed-Free End Column Design

I am currently working on a problem where I have to design a column. The structure I am currently designing currently takes the following form, When designing the column, I know that I have to ...
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1answer
57 views

Solving for stiffness matrix numerically by a set of measurements

Is it in general possible when you have a mechanical structure (in this case I am referring to the structure in this post) and you want to determine the global stiffness matrix of this structure, to ...
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1answer
57 views

Calculate forces/ torques on a parallel spring array

I am stuck on the calculation of forces on a certain system involving parallel springs. The schematic of the system is as follows: The lower plane is fixed and the upper plane movable. There is a ...
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2answers
232 views

How do you find the resultant hydrostatic force on a curved surface which is not exactly semicircle

Assuming this is a pressurized chamber with hydro-static force acting on a semi circle stuck in a surface: To find the resultant force, I would first divide the semicircle into half. Pressure on ...

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