13 votes
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Calculating torque needed to climb a graded hill

I think you're overcomplicating things. To push 85 kg up a 15% slope against gravity of 9.8 m/s2 requires a force of $$ \sin (\arctan (0.15) ) = 0.1483 \approx 0.15 $$ $$F = 85 kg \cdot 9.8 \frac{m}...
Dave Tweed's user avatar
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5 votes
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What does it mean for a machine design to be "kinematic"?

I think it might be shorthand for a kinematically constrained design. It is the ...
Frodyne's user avatar
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5 votes

What do I need to operate this motor?

I recommend researching motor driver circuits. These motor drivers internal has a H-Bridge design and have both direct on of digital signal to manage both direction (forward, backwards) and stop. You ...
Mahendra Gunawardena's user avatar
4 votes

How to calculate the velocity of a piston-like linkage?

The angle $\beta$ can be obtained from the geometry $$ 0.2*1000 \sin (\beta )+50 \sin (60 {}^{\circ})=150 $$ This gives $\beta = 0.5627 rad$. Assuming the angular velocity of the arm relative to B ...
Suba Thomas's user avatar
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3 votes
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4 Gears in a Circular Pattern - Calculating the Proper Distances for Meshing

Let’s consider gears as being represented by a pitch circle on which lie several equally spaced dots with a number equal to the number of teeth. These dots can either represent the teeth or the gaps ...
Involute's user avatar
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3 votes
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Why do 2 points on a mechanism not have the same angular velocities?

The velocity of P' is perpendicular to AD, and the velocity of P is perpendicular to BP. So clearly the directions are not the same. Thus there is relative velocity between P and P' as shown in the ...
Suba Thomas's user avatar
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3 votes
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How to interpete the formula: $I_{G}\alpha = \dot{\vec{H}}$?

Perhaps it is helpful to compare the equation to its linear counterpart. $$ \begin{align} \vec{F}&=\dot{\vec{p}}=m\vec{a}=m\dot{\vec{v}}\\ \vec{\tau}&=\dot{\vec{H}}=I\vec{\alpha}=I\dot{\vec{\...
Chris Mueller's user avatar
3 votes

Mechanical Engineering: How To Amplify Kinetic Energy In Axial Rotational Gear Machinery?

A simple machine is what you're referring to. A simple machine turns motion into mechanical advantage. Examples include: lever inclined plane pulleys wheel & axle gears inclined plane/wedge/...
Tiger Guy's user avatar
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3 votes
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Inverse of quaternion kinematic matrix

In order to make the notation shorter for the remaining calculations in my answer I will denote the matrix with $$ H = \frac{1}{2} \begin{bmatrix} -q^\top \\ q_0\,I_3 + q^\times \end{bmatrix}. $$ In ...
fibonatic's user avatar
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3 votes
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Is there a simple trigonometric relationship between these two angles?

Since considering four-bar linkages is a useful tool in my research field, I happen to know of a paper that precisely solves what you want to do. George H. Martin published in 1958 in the journal ...
OpticalResonator's user avatar
3 votes

Why can’t we accelerate a rotating object after some point?

This gets back to the original answer by Tigerguy. You have the maximum torque your legs can put out. You also have the maximum power your legs can put out (power = torque x rotational speed). But you ...
PatMc's user avatar
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3 votes
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Relationship between how fast a metal cylinder can spin on its axis without breaking or deforming?

For a thin spinning disk ignoring the frictions, such as air friction, there are two stresses, radial and hoop stress. Both must be below the accepted stress limit of the material. We assume no ...
kamran's user avatar
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2 votes

Calculating torque needed to climb a graded hill

The answer provided by Dave is correct but it covers only a very specific case of no-friction and constant speed. There are three forces acting on a vechicle which must be accelerated from 0 to v ...
jumpjack's user avatar
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2 votes

What is meant by "shock load" in gears?

a shock load on gearing is imposed when the gear train is forced to start or stop turning very suddenly, or when a heavy load is suddenly applied to a set of rotating gears. A good example of this is ...
niels nielsen's user avatar
2 votes
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Purpose of normalization of Jacobian in a parallel manipulator

It is because you are using the trace of the matrix, which is equal to the sum of the singular values. The ideal $\mathbf{JJ^T}$ has singular values all equal to 1, but for an $n \times n$ matrix ...
TimWescott's user avatar
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2 votes
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Questions on machinery terminology

Answering your first question: In the control field of mechanical engineering, a spring can indeed be a link. In the book Modern Control Engineering by Ogata, Katsuhiko the spring is frequently used ...
Edwardo9's user avatar
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2 votes
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To stop or to go around?

Each car depending on its handling has a maximum safe turning speed $v_{max}$, and radius $r$. Let us say the current speed $v<v_{max}$, then your turning angular velocity is $$\omega= v/r.$$ We ...
kamran's user avatar
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2 votes

Mechanical Engineering: How To Amplify Kinetic Energy In Axial Rotational Gear Machinery?

No. You cannot increase both torque and speed without adding more energy to a system. In a gear train/belt & pulley combo, you have one member rotating slower but with higher torque and the other ...
jko's user avatar
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2 votes
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Firing a bullet on wooden block and then finding the average resistive force by block?

There is no need to know the mass of the block. If it were movable yes, but in this case you can assume that is a fixed wall. So the whole idea is that you are assuming a constant (average) ...
NMech's user avatar
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2 votes

Why does the 1kg mass move towards inclined plane here?

Let's assume for now the wedge S massless. its mass is not going the change the aspect of the behavior of the One kg mass. The components of the 1 kg along and perpendicular to the ramp are $$F_{...
kamran's user avatar
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2 votes
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Would a car slip down on a frictionless banked road and situation for friction road

Frictionless surface. Assuming the initial velocity is perfectly tangential to the circular motion to begin with : greater than $u_0 >\sqrt{g R \sin\theta}$, then the car will spiral outwards less ...
NMech's user avatar
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2 votes
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Frictional wheels without slipping (gear system)

The concept behind the friction force should always be greater than the tangential force is that the maximum friction force should be greater to the force that causes the rotation of the wheel. If ...
NMech's user avatar
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2 votes

Difference between body-fixed angular velocity and the rate of change of Euler angles?

I am confused though on the difference between the Euler angles and the angular position. In the picture above, I've integrated the angular rates to get the angular positions. The angular position ...
AJN's user avatar
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2 votes

Radial and transverse velocity

You could calculate the velocity magnitude from total energy (gravitational and kinetic) of the comet, which must be constant: $$E = E_p+E_k = -\frac{G\cdot M\cdot m}{r_A}+\frac{1}{2}m\cdot v_A^2 = -\...
Tomáš Létal's user avatar
2 votes
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Kinematic join for parallel axis rotation with equal inverse angles

Depending on whether you care about accurate angles displacement you could use chains or belts. Configuration 1 - Belt Not accurate If then rotation angles don't have to be the same you can get away ...
NMech's user avatar
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2 votes

Why can’t we accelerate a rotating object after some point?

This would work if input power could handle infinite speeds. On a bicycle, your legs limit how fast you can pedal and the power you can input to the system. Motors have speed limits as well. The ...
Tiger Guy's user avatar
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1 vote

What does it mean for a machine design to be "kinematic"?

See https://en.m.wikipedia.org/wiki/Kinematic_coupling A kinematic coupling is constrained in (only) 6 degrees of freedom.
Jonathan R Swift's user avatar
1 vote

Bending Moment Doubt

When you constrain a beam end to point in the same direction as the clamped end (which is the case with the lower beams), then you have to apply a moment equal to $Ql$ (where $Q$ is the end load and $...
Chemomechanics's user avatar
1 vote

What is meant by "shock load" in gears?

In gear design for different machinery there is a combination of loads that causes damage and excessive wear and the equation for that load: F* = Ka Kv Km Ft Ka is application factor inherent ...
kamran's user avatar
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1 vote
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Euler rotations and acceleration

First of all you need to be about which reference frame you are estimating the acceleration of A. I assume you need the accelation of A wrt to the inertial frame of reference. The most generic way is ...
NMech's user avatar
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