Questions tagged [applied-mechanics]

Questions about using applied mechanics to model engineering problems.

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Calculating torque in planetary gearbox

It's my understanding that in a planetary gearbox, force moves through the system via four mechanisms: the ring gear, the planet gears, the planetary carrier, and the sun gear. I'm trying to ...
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3 answers
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Work done by a force in a deformable body

Consider a deformable body that is acted upon by several forces at different points of application. Under these forces, the body remains at rest but deforms and the particles have some displacement. ...
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Is kinetic energy on a body in vacuum = 0?

We know kinetic energy =$\frac{1* mv^2}{2}$- $\frac{1* mu^2 }{2}. $. u=initial velocity & v=final velocity. So , for a body in uniform translational motion I.e acc=0 & velocity is constant. ...
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How to solve this complicated truss system?

Below is a truss I simulated in a truss calculator. I'm just wondering, how to solve for the compression and tension of each member and are there any method that can solve this? My solution is I ...
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Center of gravity

Say an aircraft without its engines has a mass of 118 tonnes and balances on its rear wheels only. This must mean the center of mass of the aircraft without its engines is directly above the rear ...
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What should be the mass of block A so that the system stays at rest?

Q: What should be the mass of block A so that the system stays at rest ? Conditions: i) No normal force is present at point of 2kg mass. It doesn’t mean N=0. ii) No friction , mass of string & ...
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How to Calculate Approximate Fuel Consumption from Engine Specs

I have a marine diesel engine, and I'd like to calculate the approximate fuel consumption based on the size of the engine, at a given number of RPM - specifically for the cruising recommended cruising ...
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How to replace these two forces with one force?

Here, $P>Q$. $O$ is the center of mass of the rigid and uniform bar/stick. As $P>Q$, the resultant is situated to the right of $\vec{P}$ and is parallel to $\vec{P}$. The magnitude of the ...
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I have a question regarding moments and centre of mass

Lets say a plane had 2 engines located 9m ahead of its rear wheels. Give each engine a mass of 7.5 tonnes. A force of 147150N will act 9m ahead of the rear wheels. lets say the aircraft was 133 tonnes ...
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Does the constraint equations written for pulley mass system can be any coordinate system other than rectangular

This is an example problem from the book vector mechanics for engineers. I had a doubt that how the position vectors for A and position vector B relative to A defined. That is the equation which is ...
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Is there a way to solve this complex statics problem algebraically?

This problem can be solve in 2 ways either I solve it with vectors which would be relatively painful and more time consuming and the other faster way is algebraically but I faced a problem when trying ...
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Modelling a Simple Translational System

I posted this on stack exchange physics, sadly no one has answered so I thought I'd try my luck here. I am trying to model the following translational mechanical system in I/O form, however I am ...
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Stress-strain Curve Interpretation

A significant barrier to my understanding of typical engineering stress vs. engineering strain curves is that for certain values of stress, there are multiple values of strain (i.e., the stress-strain ...
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Eight bar Linkage (Analytical solution)

Good morning, I'm trying to solve this problem of kinematics of an eight bar linkage through the analytical method. I don't want that you perform the calculation, only I would like to have a advice ...
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How to calculate the pressure applied in a compressible fluid?

If I am trying to figure the pressure needed contain a fluid like hydrogen in a cylindrical tank, how would calculating this go on? As Hydrogen is compressible to a differing amount than other ...
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Why does the string having length C not have an impact on the overall system?

The Q: Given: a1 and a2 are the accelerations of mass 8 kg , 2 kg respectively. i) Total Length of Sting $L=4 x_{1}+2 x_{2}+C$ ii) $\frac{d L}{d t}=\frac{4 d\left(x_{1}\right)}{d t}+\frac{2 d\left(x_{...
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Why is the direction of static friction towards centre in case of circular turning?

Here , a car turning on a circular track. I have marked all the kinds of friction , velocity happening in the diagram. For the front wheels , VT (Tangential velocity) ,Vr(Radial velocity) , VR(...
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Why is direction of velocity in front direction

These are how circular turning tracks look like. Now , according to my textbook: This is how it looks like. But I argue upon each & every point of it. Here , the car is turning but it’s ...
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Derivation of static & kinetic friction formula

We know formula of static friction & kinetic friction = μsN and μkN. I have searched online a lot about them. I do know what is the formula & how to use it but I couldn’t find any article ...
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For pure rolling , Proof for every point on wheel has velocity = vc + wr

There are 2 texts I have seen for every point on wheels finding out the exact velocity of certain points. The theory states for all is that : Every point on wheel has total v = rotational + ...
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Understanding velocity of points of wheel

I am very grateful to all for helping me out. Thank you. Also , It will be quicker for me to understand if you tell where at which point am I going wrong or right ? This way , I know exactly how much ...
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Energy consumed by a two-link planar manipulator with feedback control

I was carrying out a problem in which I have a fully actuated two link manipulator, so with an independent servo motor for each link that allows rotation in one direction and another (positive for ...
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Why is velocity of wheel = v0+wr?

The case we have is : A wheel is kept in a box. There are two images given. Given below are conditions of the first image: Velocity at which the wheel is turning. $\frac{d s}{d t}=\frac{d \vec{\...
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mechanism design for matrix of adjustable direction pointer

I need to construct a matrix of light pointers, each one aims in specific direction, and each pointer direction will be adjusted thousands times, size is flexible could be millimeters or centimeter ...
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Automatic Tissue Dispenser

My father is a software engineer and yesterday he asked me a question to test me, that I cannot, for the life of me, seem to figure out. He told me that I need to make a tissue paper dispenser that, ...
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Calculate effect of drag on ball in motion

So I’ve been trying to work out the range of a ball that has been projected by two spinning discs please when accounting for drag- This is what I got so far: $V=V\cos\theta$, $T=2V\sin\theta/g$ , and $...
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Root diameter and the base diameter of gear and pinion

In my design of a spurgear the root diameter in pinion is less than the base diameter but in the gear the base diameter is less than the root diameter. Why?
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Designing a grabber

I designed a grabber for grabbing strings and yarns. the movement that I need is straight up and down to grab a piece of yarn. I wanted to know if this model (in the video) works in real life or not. ...
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1 answer
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Question about theory of machines (kinematic diagrams)

Can I draw this part of kinematic diagram in this way, knowing that bolded W is a point of interest. so is my drawing true also? (my lines are in red and black(not bolded black))?
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where did the concrete splitting test calculated stress formulat come from?

In compression test of cylindrical concrete sample we get the normal stress easily by dividing failure force by sample cross section, but how we can explain the formulat used to determine tensile ...
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How to choose contravariant or covariant bases?

I completed an introductory course on continuum mechanics, but we did not delve into curvilinear coordinates with CM. However, when I read some publications I see the stress-strain relationship is ...
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1 answer
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mechanical counter using ratchet (for a pinball machine)

I have built purely mechanical pinball machines before which used score compartments the balls would fall into to keep track of points. I am now trying to find a way to count points without losing the ...
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Why does "potential energy" have the word "potential" in it?

Imagine a block of mass $m$ placed on the ground. I slowly lift it up to height $h$. The work done by me on the block is $mgh$. This amount of energy is now stored in the block when it is at height $h$...
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What will be the force F for the given brake system?

I am getting two ways to find F. One is Fx0.2=30 Nm which gives F=150N Other is Fx0.2-640x0.13=0 which gives F=416N I am confused which one is incorrect. I know problem is too basic but still not ...
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2 votes
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Bar released from upright position rotates about a lower hinge before being caught by a steel cable, how to calculate the tension on the cable?

I wish to check the safety factor of a steel cable that I've designed to catch a heavy bar that rotates freely due to the gravitational force acting on it. From the upright position, I'm assuming that ...
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Do tensile and compressive forces have significance only in pairs?

In strength of materials, there are two types of axial forces which can act on a prismatic bar - Compressive and Tensile. Do they significance only in pairs?
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Can I create a whirlpool/vortex around a horizontal axis in a flat bottle using motor?

I am using this flat bottle: I fixed a motor at the centre of one of the flat sides and attached an impeller. I thought this will create some kind of whirlpool effect but as you can guess, since the ...
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1 vote
2 answers
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Why is the theoretical formulation not explaining why the graph of the square of the velocity and angular displacement is nonlinear (experimentally)?

So I did a wind tunnel experiment where I put a rope restrained (1 degree of freedom, so it can wave in the direction of the wind) at one end so that it displaces according to the variation in wind ...
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Find the maximum stress at a point in a machine member

A machine member having a diameter of 50 mm and a length of 250 mm is supported at one end as a cantilever subjected to different forces as shown in the figure. Find the maximum stress at points A and ...
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How long does it take and how far does it travel a sphere in free fall before reaching a percentage of the terminal velocity?

Assume a sphere (hail) that is free dropping in air. At some the sphere will reach close to the terminal velocity. The question is: how long $t_p$ in seconds does it take before a percentage $p$ of ...
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1 answer
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Does the terminal velocity of a sphere in free drop increase with increasing diameter?

I was trying today to calculate the terminal velocity of a hailstones with increasing diameter and mass. I was trying to figure out if larger hailstones will have a higher impact velocity or lower. I ...
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Computing forces and moments acting on the sides of a rectangular shell element from corner forces and moments

I have a FEM program for shell elements implemented through the direct stiffness method. Using this program corner displacements of shell elements due to external loading are obtained through the ...
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Difficulty in understanding polarization? Is it only applicable for H and an electronegative element like chlorine? [closed]

There are two examples I have taken in diagram. In the first one , we have a cation and anion. They form an ionic bond due to which the cation has no electrons and the anion has 2 electrons. There are ...
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Can a beam be too short to experience bending stress?

The question in the title says it all. I've got a a configuration where I'm using a bolt to support a load. The way its set up, the bolt will have a very short cantilever on it. When I calculate the ...
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what is the torque difference in single plate clutch disks and multidisk clutches? [closed]

I have a review question that I am not sure about the answer. The question goes like this: "In comparison to single plate clutches, multidisk clutches are associated to which of the below notions?...
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Mounting grinding wheels on a threaded rod

I'm trying to mount a set of 6" grinding wheels on an M12 threaded rod. The problem I have is keeping them perpendicular to the rod so that they don't wobble when they turn. The wheels have a 1&...
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3 votes
1 answer
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How do rollercoaster designers calculate the ideal curve?

I've been looking into rollercoaster track designs and wondered how they mathematically calculate the ideal curves to fit some specific layout without creating excessive Gs or other rider discomfort ...
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2 votes
1 answer
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Free body diagram of a differential-drive mobile robot

I'm trying to study the free body diagram of this differential-drive mobile robot in case of straight trajectory (same torque applied on both of rear wheels) and pure rolling motion I started ...
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1 vote
3 answers
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How can you control the speed of a rope moving through a pulley?

I'm putting together a ceiling-mounted clothes rack. The rack is raised and lowered with rope and pulleys. If the rack is raised under full load and accidentally released, then the system could be ...
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2 votes
3 answers
196 views

Do all structures deform if put a load on them?

Suppose I have a concrete wall in front of me and I push on it, now it seems that I do work and the energy has magically disappeared. I am trying to figure out how this works, the explanation I ...
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