Questions tagged [applied-mechanics]
Questions about using applied mechanics to model engineering problems.
307
questions
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29 views
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 ...
0
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4answers
39 views
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, ...
0
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1answer
34 views
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 $...
0
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0answers
8 views
Forces at one-side-fixed lever [closed]
Given a "thing" (black line) that is fixed on the right side and should be raised at the left end by a rope that can be connected at either at A, ...
0
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0answers
29 views
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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52 views
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.
...
0
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1answer
44 views
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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27 views
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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0answers
18 views
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 ...
2
votes
1answer
44 views
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 ...
8
votes
4answers
5k views
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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2answers
61 views
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 ...
2
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0answers
30 views
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 ...
0
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2answers
32 views
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?
1
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3answers
67 views
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 ...
1
vote
2answers
103 views
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 ...
0
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3answers
40 views
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 ...
0
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2answers
70 views
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 ...
1
vote
1answer
41 views
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 ...
0
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0answers
27 views
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 ...
1
vote
0answers
26 views
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 ...
0
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2answers
99 views
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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0answers
31 views
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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0answers
56 views
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&...
3
votes
1answer
65 views
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 ...
2
votes
1answer
91 views
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 ...
1
vote
3answers
113 views
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 ...
2
votes
3answers
194 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 ...
1
vote
1answer
47 views
Calculating the diameter of screws that are on radius 160mm from axis of rotation. I need help - I don't know If I'm thinking in the right way
First of all, english is not my first language so if there are some mistakes I made - I'm sorry and I hope everything is understandable.
The example I am trying to solve reads the following:
The gear ...
1
vote
3answers
276 views
Why do we write T cos theta = mg for this Q instead of mg cos theta = T
For this Q , the author of the textbook writes that T cos 45 =mg
but it also states that mg cos 45 is not equal to T. I got to know about this because this is the way , I solved it first.
My Q :1 is ...
0
votes
2answers
69 views
Effect of centripetal acceleration on angular acceleration
$a_t$ = $\frac{dv}{dt}$ = $\frac{d(r*\omega)}{dt}$ = $r $* $\alpha$.
$a_c$ = r*$\omega^2$ = $\frac{v^2}{r}$
These are almost all the variables and values associated with centripetal and tangential ...
0
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3answers
55 views
How to guess direction of friction in any case
Here , in case of a death well situation as an example.
Q How is direction of friction going to be opposite to mg or in upwards direction ?
Why not:
In case of like circular turning , direction of ...
0
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3answers
40 views
Is there any frame of reference in which we can neglect the gravitational force?
There is a laboratory in which there is a string tied to a bob on the earth.Consider the earth is perfect sphere ,rotates on its own axis in a circular path with uniform angular velocity. Main Q of ...
1
vote
2answers
60 views
What size feet for this wind-protection panel?
I need to create a series of free-standing perspex panels to add height to an existing fence for wind-proofing purposes.
My idea is that each panel would be fixed to two supporting poles that are ...
2
votes
1answer
56 views
Degree of freedom of a mechanism
A mechanism popped up in my mind when I was studying kinematics, see picture below
$J1,\ J2,\ J3$ are rotational joints and there are two translational joints $J4$ and $J5$ between two sliders and the ...
2
votes
3answers
92 views
Would a car slip down on a frictionless banked road and situation for friction road
Here , we have a car on a banking road. Considering two cases :
Frictionless and friction surface of the road.
I give an initial velocity to the car by a push for a second. Then , the cases discuss ...
1
vote
1answer
77 views
How to generate a repeating semi-circle waveform using a mechanical linkage
How can one, in a smooth way, produce a semicircle wave, as opposed to a sinusoidal wave ?
Imagining the machinery and linkages behind the movement.
I mean the trace. For example a point fixed in ...
1
vote
0answers
50 views
How is a plank able to stop a spring door [closed]
So , here we have door which can get closed on its own due to spring. Agenda of Q is to put sth beside the door so that the door does not close .
The Q tells us that when we put a brick of 0.5kg. Door ...
1
vote
3answers
168 views
Why do I get pushed back when I’m in a car at high speed?
When I’m in a car at high speed , I get kind of like pushed back if I’m sitting on the cars seat. How does it happen and why ?
If I’m in a car , then I have the same speed as car and for the car , I ...
0
votes
2answers
90 views
Find minimum horizontal force required to keep the block and wedge stationary?
In the adjoining figure, the coefficient of friction between wedge (of mass M) and block (of mass m) is μ. Find the minimum horizontal force F required to keep the block stationary with respect to ...
2
votes
0answers
39 views
Magnetic Force - Point of Load
I am using a Magnet like this in an assembly and I am trying to calculate the torque in point P2 (see picture below) resulting from the attraction force F between my magnet and the steel part.
As I ...
0
votes
1answer
58 views
Find a constraint relation for this Q of 3 pulleys and 2 blocks attached with string
Using any method find the constraint relation between mass 1 and mass 2.
Assumptions: No friction , massless string and pulley.
Q: Find constraint relation between 1kg and 2kg block.
what I tried so ...
0
votes
2answers
57 views
Why is the acceleration of wedge and block equal like this
No friction at all anywhere. Let me explain the diagram in steps and the Q.
green colour let us start with. It represent a wedge on which there is mass of 10kg (red colour). That’s it the first ...
1
vote
2answers
66 views
Find the acceleration of a block relative to incline plane in non and inertial frames?
A block can slide on a smooth inclined plane of inclination $\theta$ kept on the floor of a lift. When the lift is descending with retardation i.e. $ a \; m/s^2 $. Find the acceleration of the block ...
0
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2answers
76 views
Why does the 1kg mass move towards inclined plane here?
Assumption :All frictionless surfaces.
EDIT: In the book , it doesn’t say friction has to be present but as PeteW has mentioned , i think it should be necessary too. So , in that case let me take two ...
0
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2answers
46 views
Why is the tension on mass m1 not 2T here?
I have named the strings as S1,S2 and S3 on diagram. T is the tension in the string.
If I draw the Free body diagram for m1, I think it should be 2T force on it but on internet , it is just T. So , ...
1
vote
1answer
46 views
Any idea on how to prove this formula of tension?
The formula is:
$$T= \dfrac{\left(\sum (\text{coefficient of tension})_i\right) \cdot g_{effective}}{\sum \frac{(\text{coefficient of tension})_i^2}{m_i}}$$
I tried to prove this formula but not ...
7
votes
2answers
2k views
How do suction cups work?
These are suction-mounting hooks. I want to visualize and understand how do they stick on walls.
After these hooks stick on wall. Like we compressed them. How? Since gases are compressible up to a ...
2
votes
1answer
45 views
Firing a bullet on wooden block and then finding the average resistive force by block?
For a Q in which we are firing a bullet of 0.04kg onto a wooden block which is stopped after a distance of 60cm after penetrating inside it. It’s u=90m/s.
For this Q , we can find a=-6750m/s^2. Using$ ...
0
votes
2answers
63 views
Why is final momentum found by two formulae in case of increasing force not equal?
So, let us say a body moves with 10 m/s, mass = 10 kg.
At time t=0 a force of 30 N is acting on it. Gradually (linearly) the force increases and finally it becomes 130 N after a period of 2 second .
...