The tendency of a force to rotate an object about an arbitrary axis.

learn more… | top users | synonyms

0
votes
1answer
46 views

Finding the coefficient of friciton [closed]

I'm asked to find the coefficient of friction before the bar starts sliding. Here is my solution -> ∑M = 0 -mg * 1.4863 + 1.8159*T = 0 (T*1.8159) i found by using a cross product ( -2.9726i+ ...
0
votes
1answer
91 views

Who told us how to measure torque?

We all know that force and torque are physical quantities which we have defined according to our purpose of work. Now we are all aware that Newton's Second Law from his Laws of Motion states how to ...
0
votes
0answers
26 views

How rotational force calculation depends on the distance between the point of force application and the axis of rotation?

I don't understand how the perpendicular distance between the point of force and the axis of rotation gets involved in the calculation of the rotational effect of that force.Is it about rotational ...
0
votes
1answer
27 views

Finding the friction before slipping [closed]

There is a string that is attached to a bar as shown below in the picture. What is the coefficient friction between the bar and floor before bar starts slipping. I have chosen a pivot point about ...
0
votes
2answers
58 views

Equilibrium equations

You have one horizontal beam. Its left point is attached to a free pivot at the vertical wall. Its right point is suspended by a rope from the ceiling. Nothing is moved. So $\sum F=0$ and $\sum M=0$. ...
-1
votes
1answer
45 views

A leaf floating on the surface of water (in $x$-$y$ plane) curl along positive $z$ axis [closed]

A leaf floating on the surface of water (in x-y plane) show that for a very small circular leaf ($\nabla \times \overrightarrow v $) is equal to twice the angular velocity of rotation of the leaf, ...
0
votes
0answers
15 views

How do I calculate the best mass for the highest linear speed?

I have a motor whose specifications say that its torque is 190g*cm. If I have the formula for the mass of the wheel vs radius, is there any way I can find the optimal radius to get the highest linear ...
1
vote
3answers
102 views

Does KV in rc motors (RPM/Volt) tell us anything about the torque?

Considering that KV is RPM/Volt, does it ever tell us anything about the torque? Wouldn't you need to be told the torque separate from the KV rating? If torque can be derived from a KV rating then ...
0
votes
0answers
44 views

Moment of Inertia of a Motion Simulator Frame

I have a rather specific question. I'm trying to build a motion simulator for flight and racing sims, similar to this: https://www.youtube.com/watch?v=JQAZB3EnI_w . The basic concept is a platform ...
0
votes
1answer
112 views

torque in electric dipole placed in nonuniform electric field

In the uniform electric field case, we can know the rotational axis is at the position in the middle of positive charge and negative charge. However, if the electric field is non-uniform, or simply ...
0
votes
1answer
42 views

Acceleration of two points problem (mathematical explanation)

There is a square board with two nails in corner A and B. We apply a torque $M$ to the square board. Nail A can move freely on a track only in the $x$ direction and B only in the $y$ direction. The ...
2
votes
0answers
35 views

Why does a balance try to be horizontal? The moments are equal [duplicate]

Suppose we have an ordinary balance where equal weights are put in both sides. Now one side is slowly held down. When this force is not applied anymore, the balance tends to achieve horizontal ...
0
votes
3answers
35 views

Minimizing time of a rotating pole

I've been trying to solve this problem for a while now but I'm not sure exactly what I must do in this scenerio. The scenerio is as follows: There is a pole of arbitrary length attached to a point ...
0
votes
1answer
163 views

Finding torque due to normal force [closed]

A cubical block of mass $m$ and edge length $a$ slides down a rough inclined plane of inclination $\alpha$ radian with a uniform speed. Find the torque of the normal force acting on the block about ...
0
votes
1answer
125 views

Why is torque the cross product of the radius and force vectors?

I understand the torque vector to be the cross product of the radius (moment arm) and force vectors, but that means the torque would be perpendicular to the radius and force vectors, which makes no ...
0
votes
1answer
69 views

Doubt related to rotational motion (rolling down an inclined plane)

I have doubt regarding when an object ( sphere , ring , cylinder etc ) rolls down a FRICTIONLESS inclined plane. Let us suppose the angle of inclination of inclined plane is θ. Now the forces acting ...
0
votes
1answer
77 views

Confusion between TWO shear stress formulas

There are two formulas that I have encountered so far for shear stress in my Engineering class. Let S be shear stress, F be force, and A be cross sectional area: S = F/A Note: This formula is ...
0
votes
1answer
82 views

Torque when net external force is zero

I was studying force couple and my teacher said that in this the torque about any point is same. That led me to wonder if in any case if net external force is zero then is torque about any point in ...
1
vote
1answer
85 views

Contradiction in a simple torque/rotation problem - two ways of calculating external force don't agree

Suppose we have a rigid system of two point objects (both of unit mass) connected with a massless rod, with the objects horizontal on the x axis, at a distance $r_1$ and $r_2$ from the origin, ...
0
votes
1answer
47 views

Lever Mechanical Advantage

In the attached image the force output of the plank is calculated to be the work done (FDf) divided by the height the block rises (Dw). So the force the plank applies on the block is (FDf)/(Dw). But ...
1
vote
2answers
105 views

How to calculate force / torque on non-flat lever, i.e. dolly

See attached image. The mass is being rotated on a lever where the pivot point (P) is a certain distance ($L_2$) from the right angle at the bottom. How do I calculate the force necessary to apply ...
0
votes
2answers
97 views

Apply force to one end of a rod in space: why not purely translational? [duplicate]

Why does applying force to a rod in space (or any other isolated systems) on one end leads to both translational and rotational motion? Here's my logic: suppose there is a rod in space. We ...
-1
votes
1answer
30 views

Why can't we have more than 3 moment equations in equilibrium equations

Excuse me for a kind of stupid question but, In statics of a 3D rigid body, the equations to determine equilibrium are at most 6 (Fx Fy Fz Mx My Mz = 0) (not counting those from hinges and rollers). ...
0
votes
1answer
86 views

Question about Torque Reaction of a Helicopter

This image below about the torque reaction of a helicopter has confused me a bit. I would like to ask whether i understand the principles here correctly. In the picture we see a helicopter whose main ...
-1
votes
2answers
94 views

More torque or more horsepower? Which engine is more powerful [closed]

Two internal combustion engines : $250\,\mathrm{hp}$ and $900\,\mathrm{Nm}$ torque $770\,\mathrm{hp}$ and $790\,\mathrm{Nm}$ torque Which of the above two engines will be more powerful? P.S. ...
1
vote
1answer
60 views

Rotational motion - torque

I recently read a book of introduction of the rotational motion, but I do not quite understand the way author analysed the problem. Situation: A light rod rests on a pivot passing throughout its ...
0
votes
0answers
23 views

How is the torque on the support?

I simulated with Spaceclaim Ansys this device I would like to study: https://youtu.be/Pjc4dIf1aWI The friction is very low. I drawn a fixed black circle on the orange disk to look at the angular ...
2
votes
1answer
41 views

Will a coin topple if the center of the coin is just on the corner of the square table?

3/4th of the coin is outside the table and 1/4th is on the inside. Also assume that the center of the coin is just on the inside.
0
votes
1answer
141 views

Calculating output forces of bicycle wheels

Based on the force on the rear gear $F_t$ and the radii of the rear gear $R_g$ and rear wheel $R_w$ , how would you calculate the force the bicycle exerts on the ground when it is accelerating? I ...
-1
votes
1answer
75 views

From where does the fan blade gets torque?

Any sort of angular acceleration produced in a body is due to its torque. Now, consider the fan, it's weight passes through the centre of mass, so torque is 0. Now, is it the motor that is attached to ...
2
votes
0answers
43 views

The underlying chemical interactions behind torque

I did some searching around, and didn't find any previous topics that address torque in this specific way -- here goes: Say I just have a plain ol' piece of wood -- relatively long in one axis, so it ...
0
votes
1answer
57 views

Calculate torque to rotate and 84lb panel vertically from 0 - 90 degrees

I have a rectangular panel that weighs 84lb. Width (rotational axis) is about 60-inches. Height is about 32 inches. It will be lying flat and hinged (or connected to tubular motor) on the long edge. ...
0
votes
2answers
131 views

Does a body always rotate purely about its center of mass? [duplicate]

For example : A rod is held stationary in vertical position on a smooth horizontal ground and then released. Now the center of mass has velocity and acceleration and every point of the rod has some ...
0
votes
1answer
153 views

How can angular velocity be constant even when there is a torque by friction?

A cylinder at rest lying on a rough ground is given an impulse which imparts a translational velocity (no angular velocity) to it. The question goes ahead with finding time after which rolling starts ...
0
votes
1answer
65 views

How to calculate torque needed to rotate a ring held captive between two parts with a known compression force?

I'm wondering how to find the torque needed to rotate a ring that is held captive between two plates with a known friction coefficient, radius, and compression force. I'm assuming that the mass of the ...
0
votes
2answers
135 views

Magnitude of a dipole moment [closed]

I am now learning Electromagnetism, and I am doing the practice question. However I am stuck in the following question. A uniform electric field has a dipole placed in it. If you rotate the dipole ...
2
votes
2answers
147 views

Which moment of intertia do I need to calculate torque

I'm trying to calculate the torque needed to rotate an array of solar panels. I've found some formulas for calculating torque, but they require moment of inertia. I designed this array in Autodesk ...
0
votes
2answers
151 views

Is torque still a vector in 2 Dimensions?

In 3D, torque is defined as $\vec{r} \times \vec{F}$ which is a vector, therefore having both a direction perpendicular to the plane of $\vec{F}$ and $\vec{r}$ and a magnitude of ...
0
votes
1answer
30 views

potential energy of a segment of an ideal chain under external force

I want to construct the partition function of an ideal chain under applied external force. Let's say we apply force to both ends (with opposite sign) acting in z-direction and a segment of the ideal ...
1
vote
1answer
141 views

How to make a body rotate about a line that does not go through its center of mass by applying external torques

In space, is it possible to make a body rotate a point that does not go through its center of mass by applying external torques?
0
votes
1answer
115 views

How to work out the gravitational potential energy of rotating rod

I know that the kinetic energy of a rotating rod is $$ KE_{rot}=\frac12I\omega^2 $$ where $I$ is the moment of inertia. But is there some way to calculate gravitational potential energy using just ...
0
votes
2answers
253 views

A lever arm-definition question

My question is regarding Torque, and specifically the definition of the lever arm. As far as I've understood, the lever arm is the line perpendicular to the line of action to your reference point. ...
0
votes
0answers
50 views

How to determine how much torque a hollow cylinder can take?

I'd like to calculate how much torque a hollow cylinder along its axis can take before it will start to buckle. The cylinder is held at one end, and the torque is applied equally in discrete ...
-1
votes
1answer
108 views

Torque-direction of rotation

Taking moment about $A$, the mass of 2.0g and 0.50g is rotated in the clockwise direction is because they are both directed in downwards position? while $R2$ is acted in upward direction, so it is ...
1
vote
3answers
100 views

Can the anti-torque of a motor be used to spin a space vehicle about it's axis?

Imagine an electric motor together with its power supply in space. What exactly will happen to it if it is suddenly powered? Will it spin about its axis, or it will experience no motion relative to an ...
0
votes
1answer
58 views

Drag in low earth orbit

So I'm looking at the following problem; Arrow type configuration in orbit. Each end of the arrow has a mass and a cross sectional area (we can assume the head and tail are connected by a ...
0
votes
1answer
107 views

Torque Approximations Neglecting Friction

Disclaimer: I'm not asking for homework help. I don't understand how my calculations work out conceptually. If you can help me understand the connection between the concepts, I'd really appreciate it. ...
0
votes
0answers
45 views

Shaft acceleration with a gearbox

I'm trying to calculate the shaft acceleration when there is an engine, a gearbox, and a load. I've seen the equations which change the reflected inertia via the gear ratio, relate the speeds and ...
0
votes
0answers
76 views

Deduce v(t) from power and torque

I'd like to know if this is possible to draw the highest curve of $f : t \longmapsto v(t)$ of an accelerating car based on power and torque curves like this one (EV) or this one (TV). I assume we ...
0
votes
2answers
130 views

Generalization of torque and angular momentum

Question: in the simple equations $\tau = r \times f$ and $L = r \times p$, what is the origin of the vector $r$? In many textbook discussions on rotation of a rigid body about a fixed axis, $r$ is ...