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

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7k views

Torque And Moment Of Inertia

I am reading the two concepts mentioned in the title. According to the definition of torque and moment of inertia, it would appear that if I pushed on a door, with the axis of rotation centered about ...
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2answers
526 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
62 views

Why dosen't my boomerang return [closed]

My boomerang I built will only turn just a bit back towards me, but that's it, but why? Is it my design, I incorporated the recommended dimensions from the website I used, such as an 107 degree ...
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1answer
111 views

Boomerang torque and angular momentum

I'm building a boomerang for a project, but I've made it a goal for myself to have a boomerang which can fly at lest 200 feet, so how would I increase the flight path. Angular momentum increases in ...
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2answers
61 views

The concept of torque among other unknowns

Someone asked me this question and I am going to try to ask it as 'proper' as possible. Imagine there is a door and it needs a mass on the floor at the edge of the door to keep it from swinging shut. ...
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1answer
73 views

Moment of inertia help [closed]

Okay so lets say I have a lever with 2 objects on it, object one and object 2. Object 1 has a mass of $m_1$ and is $r_1$ away from the fulcrum; object 2 has a mass of $m_2$ and is $r_2$ away from the ...
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2answers
87 views

What does torque depend upon?

What does torque depend upon? I know torque depends on force and moment arm, but does it depend on choice of origin? Because I think choice of origin determines its moment arm.
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1answer
110 views

How does the weight of the pendulum's bob cause a torque?

I know that a force will cause a torque if the force has a perpendicular component to the distance from the pivot point. However, in the figure above, I can't seem to visualize how the weight of ...
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2answers
102 views

Applying a force on a rigid body which is used to create torque

In the above picture, I have a rigid body, in turquoise, which is connected to a point, the red circle. The dotted lines are used to divide objects or lengths, they are not part of the rigid body. ...
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1answer
545 views

Torque due to Gravity

I have learned that a torque on an object due to the gravity can be calculated as if the gravity acts on the center of mass of the object when the object is near the surface of the earth. Now I want ...
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3answers
261 views

Chinook Helicopter Torque

The Chinook Helicopter has 2 rotors to counteract the torque generated by spinning the blade. Theoretically, could you use a smaller "back" rotor that is farther away from the main rotor to achieve ...
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1answer
2k views

How is torque equal to moment of inertia times angular acceleration divided by g?

How is the following relation true $$\tau = \large\frac{I}{g} \times \alpha$$ where $\tau$ is torque, $I$ is moment of inertia, $g= 9.8ms^{-2}$, and $\alpha=$ angular acceleration.
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1answer
146 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 ...
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2answers
37 views

Instead of a dynamo-meter, why can't we use $\tau=I\alpha$ to determine the power of a rotating shaft?

To measuring the power of a rotating shaft, dynamo-meters are used. Instead, why can't we find torque using Torque=Moment of Inertia times Angular Acceleration, $\tau=I\alpha$? And given that we know ...
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2answers
137 views

Boomerang physics and aerodynamics

I posted a question before on this website asking how to build a boomerang for a project which can fly at least 200 feet, so how would I increase the flight path. A user responded with: slow down the ...
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1answer
52 views

What happens when a force is not applied on the centre of the mass? [duplicate]

The answer to this question force applied not on the center of mass states that for a force applied not directly on the center of mass will have the same linear acceleration as one applied on the ...
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1answer
46 views

Torque from Gravity

If a sphere rolls on an inclined plane, why does the component of gravity parallel to the plane not exert a torque on the sphere? Shouldn't infinitesimal mass particles experience a force of ...
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2answers
551 views

What causes a tall box to tip over on an inclined plane?

I'm wondering what makes a tall box rotate about its edge (the red point on the figure below) on a inclined plane (with or without slipping), when subjected to forces of gravity and friction only: ...
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2answers
140 views

Free vs bound vectors and torque

When considering basic Newtonian mechanics, we can treat vector as free and move their point of application at will. This is consistent with the affine nature of Euclidean space. However, when ...
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3answers
198 views

Why doesn't a block rotate due to friction?

In a horizontal surface, a block (cube) is sliding due to a sudden push. When the block slides, there is frictional force which is acting on the block. Frictional force will have a torque around ...
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2answers
212 views

Why neglect friction when computing torque?

There is a block of wood on a plank, with friction, and the block is moving down with uniform speed. They are asking what is the torque acting through the center of the block. My doubt is that ...
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1answer
316 views

The choice of pivot point in non-equilibrium scenarios

It is true that under equilibrium condition, no matter what pivot point one choose, the resulting net torque will always be zero. I wonder if this principle apply to non-equilibrium scenarios as well, ...
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2answers
191 views

Is the moment of a force the same about any point?

I know that when a body is is equilibrium There is zero resultant force in any direction, i.e. the sum of all the components of all the forces in any direction is zero The sum of the moments about ...
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1answer
205 views

Newton's second law for rotation

Can the second law of motion for rotation, $\vec{\tau}=I \vec{\alpha}$, be used for any axis? Is there any case that acceleration $\vec{\alpha}$ is not in the direction of applied torque ...
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2answers
350 views

Force acting on an object?

You have a bar of metal in an environment with no gravity. A force is applied on one end of it. How does it rotate? There is a non-zero torque on any random point selected on the bar. For example, ...
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1answer
797 views

Calculating torque in 3D?

Say you have a sphere, and you have several torque vectors acting on it, all at different points. Say you have the vector (6i + 3j + 5k) originating from point A, and the vector (3i + 1j + 9k) ...
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1answer
335 views

How to sum several thrust vector on a single object (like a plane)

I'm a developer. I tried (mostly for fun) to create a realistic physic engine. I try to sum all forces (here thrust) applying to an object in two composantes: an acceleration vector and the angular ...
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1answer
3k 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 ...
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1answer
70 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
1k 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
74 views

Why is it easier to go uphill on a lower gear?

In cars as well as bicycles, when we are on a lower gear, the driving wheel (the one on the wheels) has a bigger radius compared to when on a higher gear. So on a lower gear the bike/car would move ...
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0answers
57 views

Calculating the torque required to move a heavy object (the calculations)

I wanna choose a motor for my bicycle and turn it into an electric one. So the physics part shoots. The force (Force=Mass x acceleration) that i will exert on earth surface(weight) will be my ...
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1answer
29 views

What is the effect of Torque Steering on a motorcycle with a long wheel base

From experience, it appears motorcycles with a large wheelbase coupled with a long handlebar (say a modified Harley Ape Hangar) shows a noticeable tendency to veer to a side during acceleration vs a ...
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28 views

Question about calculating the torque of a magnet in an additive field

I did an experiment in the lab today where I placed a magnet in between two coiled magnets, with one coiled magnet having its south side up and north side down and the other coiled magnet with the ...
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0answers
61 views

Calculating rotation using moment of inertia [closed]

I have an object A. I know its theoretical moment of inertia. I have a string wrapped around object A. I then apply a certain tension to that string, causing the object A to spin for a certain ...
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1answer
55 views

Ideal Rolling Motion on Surface with Friction

I have a question concerning ideal rolling motion on a surface containing friction. By ideal rolling motion, I mean the tangental velocity of the rolling object is the same as the velocity of the ...
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1answer
226 views

Acceleration of Center of Mass in Rotational Motion

I have a question regarding the acceleration of the center mass during rotational motion. From my understanding, Fnet = m*a(center of mass). Also, Torque = angular acceleration * moment of inertia. ...
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0answers
73 views

Maximum friction force for a wheel to be able to roll

The wheel with mass $M$ and radius $R$ below is free in space (it is not on the ground). A torque $\tau$ is applied to it through an engine. A horizontal force $F = \frac{\tau}{R}$ is also applied to ...
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0answers
129 views

Torque of person on bridge [closed]

Consider a 10 meter bridge that weighs 500 N supported at both ends. A person who weighs 750 N is standing 2 m from the end of the bridge. What are the forces $F_a$, $F_b$ holding the bridgeup at ...
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0answers
53 views

Pressures in multiple hydraulic drive system circuits when driving common drive shaft

Assume that there are two 'idealised' and identical hydraulic drive system circuits each consisting of a connected positive displacement pump and hydraulic motor where both motors (from each ...
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1answer
126 views

How much wind does it take to tip a sign over? [closed]

Or said another way - how much counterweight does the base of a sign need to keep it from tipping over given a specific max wind? Assume the sign does not let wind through Assume the base of the ...
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3answers
320 views

Why does the moment of force (aka. torque) depend on the perpendicular distance?

Couyld anyone explain how the lecturer concluded that $$(\underline{r_2} - \underline{r_1}) \times \underline{H} = \underline{p} \times \underline{H}$$
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0answers
36 views

What will be the direction of the force required on the ball to move the ball up the stairs?

Is this diagram correct? The point of force A is at the farthest distance from the fixed centre O ,so the moment arm CD is greater and therefore,maximum torque would be produced.Is my concept ...
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0answers
36 views

How does a simple weighing balance actually work? [duplicate]

I have made a simple sketch of how I think the system looks like. My problem is: I always thought that the angle the balance makes is a function of the difference between the two masses (or the ...
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1answer
45 views

Have I calculated the Newtonmeter ($Nm$) of torque for my corded drill correctly? [closed]

The corded drill is rated at: 450watts at 3000rpm the calculation I have used is: $$\frac{450}{3000} \times 2 \times \frac{3.14}{60}=0.0157 $$ I feel I have made a basic error somewhere (as the ...
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0answers
98 views

Rolling in 3D using Torque, Angular Momentum/Velocity

I'm stuggling to get a simulation working correctly. Below you can see what I am attempting to do. You can also view it here. Can you spot where I'm going wrong? (Calculated at start) 1) Inertia ...
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2answers
760 views

Why can't the units of work and torque be interchanged? [duplicate]

When I'm studying about work and torque, I found that their unit are the same. But, why don't we use Joule (unit of work) instead of Newton-meter (unit of torque)? Since $\mathrm{1\ Joule = 1\ Nm}$, ...
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0answers
146 views

How to measure the energy required to pedal an exercise bike

I have hacked a FitDesk exercise bike to output the RPM of the pedals and the position of the resistance control within its range of travel. I want to characterize the energy that is required to ...
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1answer
326 views

Arduino Servo Torque Calculation for a Automated Telescope

I have a class project where I am using several servos to control a telescope. I'm trying to figure out the torque needed to rotate the tilt of the telescope with a servo from 0 to 90 degrees. I ...
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228 views

Angular Momentum Conservation in Gravitational Interaction

thanks for any help. I'm trying to show that in a 2body problem, angular momentum is conserved given that $\dfrac{dp}{dt}=\dfrac{-GMm(rv)}{r³}$, where p is momentum, t time, G gravitational constant, ...