The torque tag has no wiki summary.
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6answers
2k views
Why is torque not measured in Joules?
Recently, I was doing my homework and I found out that Torque can be calculated using $\tau = rF$.
This means the units of torque are Newton meters. Energy is also measured in Newton meters which are ...
11
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5answers
593 views
Why does the weighing balance restore when tilted and released
I'm talking about a Weighing Balance shown in the figure:
Press & Hold on onside of the horizontal beam and then release it. It makes some oscillations and comes back to equilibrium like shown ...
5
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2answers
64 views
How do objects change their axis of rotation?
If I hold a pencil at its end and spin it, throwing it upwards, it will spin about its end, but will soon start spinning around its center. How is this?
I would draw the following torque diagram for ...
5
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1answer
320 views
Wind turbine: Single large propeller or multiple small propellers?
Assuming smaller propellers would spin even in very low wind, whereas a large propeller would stall;
Would it be efficient to use a bunch of propellers from axial fans geared to a single motor ...
4
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3answers
2k views
Why are bicycle pedal threads' handedness left on the left and right on the right?
I understand the reason that bicycle pedals are oppositely threaded on either side. What I don't understand is why it works because I'm missing something.
Take the right pedal for example. It's ...
4
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3answers
389 views
Electric engine transmission
If we compare a petrol engine and an electric engine car, it is sufficient for the electric engine car (e.g Tesla Roadster) just to have 1 gear (forward), whereas petrol engine can have up to 7.
Why ...
4
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3answers
235 views
Meaning of the direction of the cross product
I was doing calculations with torque and then I came across something very confusing:
I understand that the magnitude of the torque is given by product of the displacement(from the center of ...
4
votes
2answers
248 views
Which is the axis of rotation?
This should be simple, but it keeps bothering me. If a rigid body has no fixed axis, and a torque (defined relative to a point $A$) is applied, it will rotate around $A$. But often I can also ...
4
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4answers
708 views
How do levers amplify forces?
This is really bothering me for a long time,
because the math is easy to do, but it's still unintuitive for me.
I understand the "law of the lever" and I can do the math and
use the torques, or ...
4
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1answer
900 views
finding angular velocity and regular velocity when bouncing off a surface with friction
Take the game of pong as a simple example. When you hit the ball with a paddle that has a frictional surface, the ball will spin as well as change direction according to the coefficient of kinetic ...
4
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3answers
2k views
Why and how exactly is electric motor torque limited?
Inspired by this question and specifically this answer to it.
From my experience there's always some very specific limit to how much torque an electric motor can output. For example, an electric ...
4
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3answers
2k views
How do I calculate DC motor speed for a given load?
Suppose I have a robot of a given mass, and I'm choosing between 2 different wheels and 2 different motors to put on it. For each wheel I have the diameter, and for each motor I know the stall torque ...
4
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2answers
92 views
Thrust center in space
I have this dilemma: Suppose you have a space ship somewhere in deep space, where there is no drag force or substantial gravity. If the ship has a single engine situated in such a way that the center ...
3
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3answers
190 views
What is a “Center Of Mass” issue of a Gorillapod?
I read somewhere that a Gorillapod may have "Center Of Mass" issues when used with the long lenses.
So, I wish to understand what is a "Center Of Mass" issue?
I have to clarify that I am NOT a ...
3
votes
2answers
770 views
Dynamics of moment of inertia
I'd like to be able to determine the angular acceleration of a system of two rotating masses, which are connected so as to have a variable mechanical advantage between the two. My background with ...
3
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5answers
499 views
How much force would be necessary to hold a 6-foot steel staff weighing 20 lbs from one end of it, parallel to the floor?
This isn't a homework problem. I'm asking cause I'm wondering how strong a person would have to be to pull it off. Their arms would be extended, both hands gripping the staff at one end, and the staff ...
3
votes
1answer
358 views
Understanding moments as forces?
I was watching this lecture on analysis of stress for mechanics of materials. At time 7:20, the lecturer says that in equilibrium, the sum of forces and "moments" in each direction (x,y,z) must be ...
3
votes
2answers
510 views
Unit of torque with radians?
Usually, the angular frequency $\omega$ is given in $\mathrm{1/s}$. I find it more consistent to give it in $\mathrm{rad/s}$. For the angular momentum $L$ is then given in $\mathrm{rad \cdot kg \cdot ...
3
votes
4answers
333 views
Difference between torque and moment
What is the difference between torque and moment? I would like to see mathematical definitions for both quantities.
I also do not prefer definitions like "It is the tendancy..../It is a measure of ...
3
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2answers
874 views
Calculating torque adjustment for offset of pivot point
I'm trying to figure out how much to adjust torque, on a torque wrench when using an extension that offsets the pivot point. See this calculator for a diagram of what I'm talking about:
The trouble ...
3
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1answer
33 views
Intuitive explanation for why same force applied farther from a hinge causes larger angular acceleration than if applied closer?
A standard example of a problem involving torque is opening a door - the same force F applied far from the hinge causes a larger angular acceleration than if applied close to the hinge.
I always had ...
2
votes
3answers
831 views
Proving angular momentum is conserved for a particle moving in a central force field $\vec F =\phi(r) \vec r$
A problem I am trying to work out is as follows:
A particle moves in a force field given by
$\vec F =\phi(r) \vec r$. Prove that the angular momentum of the particle about the origin is constant.
...
2
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3answers
2k views
Torque vs Moment
I was wondering, why in Newtonian physics torque is called "torque" while in static mechanics they call it "moment"?
I prefer by far the term "torque", for not only it sounds strong, but also ...
2
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3answers
573 views
Why do rolling disc (coin) move in circular path?
We have a coin that is rolled such that it's tilted at an small angle $ \theta $.
Question:: What turns around rolling disc so that it traces circular motion (spiral as it's speed decreses)?
...
2
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2answers
283 views
Lorentz engine to run a car?
Could a Lorentz engine (like the ones that move the write head inside of hardrives) be used to run car ? Would it be possable to get it producing 60hp, and a decent amount of tourque, if so how large ...
2
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1answer
284 views
Why does the beam in a weighing balance get tilted proportional to the weights added to each pan?
I'm talking about a beam balance(a simple weighing balance with a beam and two pans hung on either side)
As answered in a previous question, the beam comes back to the original position when one ...
2
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1answer
3k views
Torque Required For a Motor to Move an Object on Wheels?
I've been attempting to calculate how much torque a motor needs to produce in order to start a stationary object on wheels moving. (The torque is being applied to the rear 2 wheels, the front 2 are on ...
2
votes
1answer
189 views
Is angular momentum always conserved in the absence of an external torque?
Consider either the angular momentum of the earth around the sun or equivalently swinging a ball horizontally on a string.
I know that with respect to the point of rotation of the swinging ball, ...
2
votes
1answer
174 views
Which speed can an electric scooter reach on a given slope?
Electric scooters are always "given" as "working with slopes up to xx%", but what does it mean?
Given motor torque and power, scooter+driver weight and wheels diameter, how can I determine at which ...
2
votes
1answer
417 views
Normal force in a compound pendulum (physical pundulum) system?
Consider a compound pendulum pivoted about a fixed horizontal axis, illustrated by the force diagram on the right:
#
Okay, I can't figure out where the normal force on the pendlum should point ...
2
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3answers
1k views
Torque homework
We have learned that Torque is equal to a force that is perpendicular to a radius (displacement); however, I just cannot grasp one of the study questions we received:
A hammer thrower accelerates ...
2
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1answer
448 views
acceleration of rings in aerotrim (human gyroscope)
I'm working on a graphic simulation (just for fun, for an open-source screensaver) of an Aerotrim - a "human gyroscope", one of those exercise/training machines with a human in the middle, perched on ...
2
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1answer
62 views
How does the weight force distribute in roughly kite like kinematic to determine torques
I have a kinematic model like the simplified following image. Assume that all points are fixed. I'm interested in how the force $\vec{m}$ distributes across $a_2$ and $b_2$ up to $a_1$ and $b_1$.
...
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0answers
147 views
Why do control moment gyroscopes exhibit “torque amplification”?
There are a number of articles that describe the benefits of using control moment gyroscopes (CMGs) over reaction wheels in inertial navigation applications. One of the primary benefits of using a CMG ...
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3answers
5k views
What is the difference between a moment and a couple?
In mechanical engineering, the torque due to a couple is given by $\tau = P\times d$, where $\tau$ is the resulting couple, $P~$ is one of the force vectors in the couple and $d$ is the arm of the ...
1
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3answers
582 views
What determines the direction of precession of a gyroscope?
I understand how torque mathematically causes a change to the direction of angular momentum, thus precessing the gyroscope.
However, the direction, either clockwise or counterclockwise, of this ...
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3answers
531 views
Time period of torsion oscillation
The time period for a wave of frequency $\nu$ is given by $T = \frac{1}{\nu}$ or in other words, $T=\frac{2\pi}{\omega}$ where $\omega$ is the angular velocity...
For the oscillation of a torsion ...
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3answers
490 views
Self Balancing Unicycle
Here is a link to a video of a self-balencing unicycle. I'm curious as to how this works. In particular:
What provides the torque to keep the rider from falling over? I know it's somehow provided by ...
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2answers
69 views
What fraction of peak horsepower do typical 4 door passenger vehicles use?
I was surprised when I looked at the power rating of the engine used on a Humvee. It's only ~190 horsepower, which is exceeded by many sedan engines.
So an obvious question is why doesn't my Camry SE ...
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2answers
101 views
comparing torque and 0-60 speed in cars
Im looking a two cars, both are the same model but ones got a 2.0L turbo petrol engine and ones got a 3.0L turbo diesel engine.
These are the full specs
2.0L Petrol
3.0L Diesel
what im ...
1
vote
1answer
89 views
Does mass concentration affect the torque induced by a force?
If you had two bodies with the same weight but one having mass concentrated more in the center, while the other had most mass concentrated on the outside, but both had the same center of mass and ...
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2answers
291 views
How do you choose the locations of forces when calculating moments?
A uniform bridge of weight 1200kN and of length 17m rests on supports at each end which are 1m wide. A stationary lorry of weight 60kN has it’s centre of mass 3.0m from the centre of the bridge.
...
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1answer
254 views
Finding the mass of bed/Patient
One of my friends has a problem and we don't know how to get this done,
We want to to know the mass of a patient who is laying on a bed. One scales was put under the foot of a bed and weighed 232kg ...
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1answer
79 views
Stability of balanced masses with different surface areas
Say I have this setup. The two round objects have equal mass and their centers of gravity at the same distance from the shaft. The objects only differ in that they have different surface areas ...
1
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1answer
118 views
Calculating the acceleration of a car
I'm trying to calculate the maximum acceleration a car can achieve with the current gear ratio. I am ignoring drag forces and friction to keep it simple.
I'm doing this by:
calculating the torque ...
1
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1answer
50 views
If a cart hits a wall, does the weight of it affect how it moves, when the center of gravity is constant?
I have a model that represents a bicycle (a wood block with wheels), and I'm balancing the center of gravity so it's the same as a real bike. However, when the center of mass is kept constant, does ...
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1answer
452 views
Gravitational torque about a bolt that a mass is hanging from [closed]
A uniform rectangle sign h=20.0cm high and w=11.0cm wide loses three of its four support bolts(at points p_1, P_3, and p_4) and rotates into the position as shown, with p_1 directly over p_3. It is ...
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2answers
48 views
Deriving $T = F\ r = I\alpha$ for a rigid body
For a single point mass :
$\tau=F_{t}r=ma_tr=(m r^2)\alpha = I\alpha$
For multiple point masses bound together : $\sum \tau_i = (m_ir_i^2)\alpha = I\alpha$
But how do we go from that to $I\alpha = ...
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0answers
37 views
Why the screwdriver roll?
I am trying my level best to give this screwdriver a vertical push only, but it is going in a circular path. I thought of uneven friction due to non-uniform normal reaction...what do you think? I have ...
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0answers
71 views
Torque, lever and mass
The Force used in a catapult is exerted near its axis.
If we double the length of the arm of the catapult, but still use the same Force at the same point as before near the same axis, does the ...
