Tagged Questions
-2
votes
0answers
35 views
How large a force is needed for a wooden block to tip over? [closed]
I just need the formula. Tried.. Force * perpendicular distance = force * [Perpendicular distance from the line of action of the force to the axis of rotation], but the answer still is not the same ...
0
votes
0answers
32 views
Confusion in connected pulleys problem
I'm having some troubles in understanding why my reasoning doesn't work in the following problem:
Problem Two pulleys of mass $m_1$,$m_2$ and radius $r_1,r_2$ are connected by a belt (like chain ...
0
votes
1answer
35 views
Calculating torque with gears and wheel-axles
For my homework in engineering, I was given a question like this: There is an axle attached to a gear, which is meshed with another gear, which has an axle attached to it. I am given the diameter of ...
0
votes
2answers
61 views
Is my physics correct or torque correct?
I would like to put this into a differential equation. This is what I have.
$$r \times F = I \ddot\theta + \mu \dot\theta + k \theta$$
What I need verified:
$\text{Torque} = I\ddot\theta + \mu ...
1
vote
3answers
66 views
Maximum angular velocity to stop in one rotation with a known torque
I have an object I can rotate with a given torque. I would like to stop applying torque once I've reached a defined maximum rotational speed. The maximum rotational speed should be defined so that ...
-1
votes
0answers
26 views
How large is the torque when a bicycle pedal turns 56 degree from a horizontal position? [closed]
How large is the torque when a bicycle pedal turns 56 degree from a horizontal position?
The answer in the book is 67 Nm
According to the torque formula $M = F \times l$
I know the value of $I$ is ...
-6
votes
0answers
40 views
How much torque can a cyclist achieve? [closed]
How much torque can a cyclist maximally accomplish (while pedaling) with their weight if his mass is 72 kg and the distance of the pedal is 17 cm from the pivot axle?
I believe I understand the ...
2
votes
1answer
47 views
Summing moments, where have I gone wrong?
Because I don't have enough rep to post images, the question is question 3 part iii) from here: http://www.mei.org.uk/files/papers/m209ju_jk32.pdf
The surface at the contact point B is rough. The ...
0
votes
1answer
149 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.
0
votes
1answer
41 views
Pendulum system: how is derived the output as Energy?
Good day to everyone,
I want to understand in which way the "Energy equation" is been implemented to this pendulum system.
$x_1(t)$: The angular position of the mass
$x_2(t)$: The angular velocity
...
0
votes
1answer
38 views
Find the bending moment of a pole attached to a moving block
I'm having trouble with the following problem.
What I've done so far:
x-y is the usual coordinate system.
$a=\frac{F}{m}=\frac{800}{60}$ and the y component of this is $a_y=a\sin{60^\circ}$.
To ...
0
votes
1answer
59 views
Direction of the torque
In each one of the following figures there's a pole of length $1.2
\text{m}$ and there's a force $\vec F = 150 \text{N}$ acting on it.
Determine the torque that is created by the force relative ...
1
vote
1answer
163 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
vote
0answers
283 views
Neglecting friction on a pulley?
So, this is how the problem looks:
http://www.aplusphysics.com/courses/honors/dynamics/images/Atwood%20Problem.png
Plus, the pulley is suspended on a cord at its center and hanging from the ceiling.
...
0
votes
0answers
70 views
Physics Problem concerning Torque and nonuniform motion [closed]
If the earth was spinning on its axis and it weighed 100 N with a radius of 42 m, and the earth spun 1 revolution every 24 hours, how many rockets would it take to counteract the earth spin? How do ...
0
votes
1answer
147 views
How can the torque a bicycle experiences be calculated based on the center of gravity, weight and a force?
The position center of gravity of a bicycle and its rider is known, and the distance from it to the point of contact of the front wheel with the ground, in terms of horizontal and vertical distance (x ...
0
votes
0answers
165 views
Torque required to rotate sand mixer [closed]
the given data is-
Mixer having one impeller(rotor) rotating in horizontal plane about vertical axis.
capacity of mixer to design $C = 250kg$
rotor dia. $D = 45" = 1143mm$
friction coefficient ...
0
votes
0answers
130 views
How do you determine the torque caused by the mass of a lever?
Suppose we have two objects sitting on two side of a lever, and the lever also has a mass, and those objects have masses. Then how we can balance $\sum τ$?
This is what I have done:
...
0
votes
1answer
146 views
Relationship between torques and centre of mass or centre of gravity [closed]
1) A wardrobe is $2$m high and $1.6$m wide. When empty, it has a mass of $110$kg and its centre of gravity is $0.8$m above the centre of its base. What is the minimum angle through which it must be ...
0
votes
2answers
252 views
Force applied off center on an object
Assume there is a rigid body in deep space with mass $m$ and moment of inertia $I$. A force that varies with time, $F(t)$, is applied to the body off-center at a distance $r$ from its center of mass. ...
0
votes
0answers
25 views
Determine the dilation temperature so as to double the speed
There's a metallic rod of length $l_1$ which is spinning around a vertical ax which passes through its center. The ends of the rod are spinning with $\omega_1$ angular speed. Determine the temperature ...
0
votes
1answer
331 views
Calculating torque in a structure
I posted this on math stack exchange but realize it is more a physics question.
I have a structure which is set up as shown in the image. A weight hangs from point A with mass $m$. Joint B is free ...
0
votes
0answers
269 views
Torque required to rotate a cement mixer..? [closed]
I need to design a motor to rotate a cement mixer which should mix one cubic meter. So, I calculated the required volume to be 1600 liters as it is an horizontal cylinder. Consider that the mixer ...
2
votes
3answers
887 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.
...
0
votes
0answers
55 views
Two particles rest [closed]
Two particles rest a distance $d$ apart on the edge of a table. One of the particles, of mass $m$, falls off the edge and falls vertically. Using the other particle (still at rest) as the origin, ...
0
votes
0answers
113 views
Load vs Leverage vs Friction on a floating pivot [closed]
If I had a standard 'cherry-picker' type of crane (lifting device), 7' high, with a 7' boom, suspending 1000# at its end,its vertical support mounted atop a 6" diameter ball-type pivot: how much force ...
0
votes
1answer
366 views
Can anyone solve this simple static equilibrium problem? [closed]
A bridge is 50m long, has a mass of 20,000kg, and rests on two pivots, A and B. The distance between A and the left side of the bridge is 10m. The distance between B and the right side of the bridge ...
1
vote
1answer
457 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 ...
0
votes
2answers
288 views
Finding work done by rotational force?
A disk with a rotational inertia of 5.0 kg·m2 and a radius of 0.25 m
rotates on a fixed axis perpendicular to the disk and through its
center. A force of 2.0 N is applied tangentially to the ...
1
vote
2answers
295 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.
...
0
votes
1answer
339 views
if a force is 1 newton metre, what is it at 2 meters?
If I have a force, say 24 kg/cm what would that equate to at 2cm? I would like to know the formulae for calculating this.
For example. If a motor can hold an object of 24kg at 1cm from its pivot ...
-1
votes
1answer
1k views
Moment calculation [closed]
Consider image below. The weight of the fire-fighter is 840 N. What is the torque of the fire-fighter's weight about P and what is the value of the force C which cancels out the torque?
2
votes
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 ...
