Pivot Definition and 131 Threads

My AP Physics notes state that counterclockwise is generally positive and clockwise is generally negative. This makes sense to me and means forces on opposite sides of the pivot point which act in opposite directions will work together, and this is the logic I applied to answer the problems...

Torque_left = 100 kg * 1 m = 100 kg·m Torque_right = 200 kg * (13 - x) m = 200(13 - x) kg·m 100 kg·m = 200(13 - x) kg·m 100 = 200(13 - x) x = 12.5 meters pivot = 12.5 m

Are we allowed to use free body diagrams in dynamic systems where there is non-negligible friction in say the rotational pivot between two linkages? If so, how to incorporate friction into the equations of motion? If not, what method allows friction to be accounted for?

So.. question: - How do I know that only the pin is at work at E and not those 2 beams? my guess: It is because those 2 beams are connected to the pin whilst the pin is the one that exerts a force on that walking beam DEF?

I think the angular acceleration is counterclockwise (and thus so is the torque) in the diagram, but what would a free body diagram look like? After the system is released from rest, isn't the only force the gravitational force about the center of mass? And if so, what's causing the angular...

I thought that the force by the pivot A on the pole AB would be the reaction force to the x-component of the gravitational force on AB. This would mean that the force by the pivot would be parallel to the pole, but in my notes from class the force vector seems to be more along the bisector of...

1) By conservation of mechanical energy we have ##m_2gl(1-\cos(\alpha))+m_1gl=\frac{1}{2}m_1v_1^2+\frac{1}{2}m_2v_2^2+m_1gl## and by conservation of linear momentum along the x-axis we have ##m_1v_1+m_2v_2=0## which gives us ##v_2=\sqrt{\frac{2m_1gl(1-\cos(\theta))}{m_1+m_2}}## and...

Hello, I have a structure with 5 pivot point and those are provided with deep groove ball bearings (see sketch). Calculation for friction losses (deep grove ball bearing): Parameters: - Number of pivot points: 5 - Friction coefficient: 0.0010 - 0.0015 (Reference) Total friction in the...

If exerted a force at 60 cm, should the force F2 be the opposite direction of F1? Thanks!

Hi guys, I don't really know how to solve this problem. The point is finding ##\omega## when ##m_2## passes from ##m_1##'s original position. Ideally, I'm thinking about some conservation of energy/momentum to apply here, but I'm quite confused. Any hint?

My initial thought was to use the conservation of energy law since there're no external forces acting on the system bullet + rod. The rod is in rest, the bullet is moving. Then after the collision, the bullet and the rod are rotating around the pivot together, so the kinetic energy of the bullet...

So first of all, I will have to find the centre of mass. ##X_{cm} = \frac{1}{M}\int x dm## likewise for Y. ##M## =150kg From the above-given points, I can find the equation of a line to be ## y =-\frac{3}{4}x +3## . Area density = ##150kg/(0.5*4*3) = 25kg/m^2## ##X_{cm} = \frac{1}{M}\int x dm...

Hi, Guys, I am building light electric vehicle for fun and hobby. I am experimenting with stuff, but have some difficulty calculating a reasonable geometry for the suspension. It is a SINGLE arm suspension and I am planing to use Fox Float Air Shock with length 190mm, it has pressure control...

Homework Statement https://cdn.discordapp.com/attachments/373928512811302912/528638926148337704/question.PNG part a )50N I cannot answer part b. Homework Equations M=FD The Attempt at a Solution Ok so if both pivots were in contact with the beam I would just equate them with the oppposite...

Hi everyone, So, as I came across a point that I'm struggling to grasp and I was hoping someone here could kindly help me out. I've attached a diagram that describes the issue. T represents all the muscles acting on the spine; R is the force of the spine (pivot). Where I get confused is why...

Homework Statement A solid rod of length L and mass M has a pivot through its center and is originally horizontal. Another mass 2M is then attached firmly to one end of the rod, and released. What is the maximum speed of the mass 2M attained thereafter? (Cornell 2009) Homework Equations Not...

Homework Statement The picture illustrates a simple pendulum and and two physical pendulums ,all having the same length ,L. Class their period in ascending order. Homework Equations T = 2π / ( I/mgh) I = Icm + mh2 Icm=(ML2/12) The Attempt at a Solution I have found the period for first...

-sorry if I got the prefix wrong. I'm working on calculating the forces on a trapeze bar, specifically, what tension I would need on guy wires to resists the horizontal forces on a swinging trapeze. If I could get the horizontal force generated by the the trapeze/pendulum I can do the rest...

Hey Wizards, I recently built a Reverse Hyper, picture attached, for my home gym. It's a basic pendulum on which weight is added. It currently utilizes 2 - 5/8'' pillow block bearings for the pivot. Each are rated to ~6.25 KN. Can anyone provide me with the equations or reference material, so...

Hi All, I want to compute the ratio of two fields A,B from different sheets ( same workbook) , using Pivot ( tho "straight" Excel will do*). I tried using the Wizard, but , in the end, could not find a way of doing it: Any ideas, please? *I scewed big when trying this.

A weightless ladder 7.0 m long rests against a frictionless wall at an angle of 65° ablove the horizontal. A 72 kg person is 1.2m from the top of the lass. What horizontal force at the bottom of the ladder is required to keep it from slipping? Στ=0 τ=FsinθdSolutions for this question always...

Homework Statement A uniform rigid bar of weight W is supported in a horizontal orientation as shown by a rope that makes a 30° angle with the horizontal. The force exerted on the bar at point O, where it is pivoted, is best represented by a vector whose direction is which of the following...

Hi I have a 3.2m platform which weighs 175Kg. One end of the platform is touching the floor but the other end is on a pivoting bolt 2.5m in the air. I need to figure out what the "load" would be on the end which is on the floor when I try to lift that end 4.5m in the air. Basically so I can...

The diagram drawn below shows a lever system fixed to a point on the left with a pivot point (circle) on the line which attaches to vertical line. I have dimensions for Y and Z and the forces pulling the lever down on the right, and the force acting upwards from below. I am trying to work out...

Homework Statement We are given a diagram to which we need to make measurements of. There is a line Y which is 9.5cm long. At one end, point X, is a force of 6,500N going perpendicular to the line; at the other end is point J, which the line continues for another 4.5cm to point P which is the...

Hello. Can anyone help me confirm the following from the Feynman tips on physics: The above diagram shows two rods, with a weight attached (the square). Each rod has a pivot attached, though the pivot on the left is fixed and cannot roll. The weight is 2 kg, and the rod is 0.5 m long. The...

<Moderator note: Thread moved from Classical Physics, hence no homework template> Hello. Can anyone help me confirm the following from the Feynman tips on physics: The above diagram shows two rods, with a weight attached (the square). Each rod has a pivot attached, though the pivot on the left...

Homework Statement There is a cyllinder with radius 0.5 m fixed on the wall. We put a 6 metres long thin rod with mass 0.3 kg on it, which does not slip. I would like to calculate the oscillating time. It is a part of a clock, so the oscillating time is probably 1 or 2 seconds, but I got...

Homework Statement You have one meter stick that weights 100g. Calculate the torgue on the stick at 20 cm mark for A. whole stick weight when the center is at 50cm B. the left and right weight of the stick are separate, "with their masses located at the halfway points between the 20cm mark and...

Homework Statement A uniform thin rod of Length L and mass M is pivoted at one end is held horizontally and then released from rest. Assuming the pivot to be frictionless, find a) Angular velocity of the rod when it reaches its vertical position b) The force exerted by the pivot at this time...

Homework Statement A rod swings freely about a pivot. Is has mass M and length L. The average force and duration of hit are Fo and t respectively. A) What is the speed of the com of the rod just after It is hit? B) what is the horizontal component of the force exerted by the pivot on the rod...

I have simplified the problem down to something like a physics textbook question, although this is a practical problem where the pivot on my rotary actuator has been damaged by a faulty driver which caused the armature to ram into the endstop. Obviously this needs better protection. My problem...

I have a question on finding the inertia of a rod with a pivot point somewhere along it's length. So the inertia of a rod is IStick cm = 1/12 *m*L2 Does L2 = (2L/3)2 = 4L2/9 -> 1/12 *m*[4L2/9] or is it something like m*L2/12 + m* (2L/3)2? If it's the second one then may I ask why it's that...

Homework Statement pivot point located at the middle of ramp( Point C). F1=250 lbs @ 12 in from point A F2=250 lbs @ 84 in from point A L=192 in angle from the ground is 25 degrees Homework Equations sum of moments equal to 0 sum of forces equal to to 0 The Attempt at a Solution I did sum...

I'm confused about this rolling without (or better with) slipping situation. Suppose to have a disk with initial velocity ##v## and angular velocity ##\omega##. The motion is to the right but the angular velocity is counterclockwise. There are no forces acting on the disk besides the kinetic...

This is of my own interest/ practice. Homework Statement A thin rod (of width zero, but not uniform) is pivoted freely at one end about the horizontal z axis , being free to swing in the xy plane (x horizontal, y vertically down). Its mass is m and its CM is a distance a from the pivot. The...

Homework Statement Consider the following classic problem: we have a rod in the vertical position with a pivot at its midpoint and a spring attached to the bottom of the rod, perpendicular to the rod. The is rotated through a small angle theta to the vertical, and released. Find the period of...

Homework Statement The problem is the following: Using a Lagrangian, find the equations of motion of a mass hanging from a massless string, with the pendulum pivot moving in a horizontal circle at constant angular velocity. I take the mass to be m, the length of the string L, the radius of the...

A rod of length L and mass M is rotating with angular velocity w about its center of mass. What is its angular momentum with respect to a rotating point 1/4L from the rod's end? What about a stationary point? Homework Equations With the respect to the center of mass, angular momentum L = Iw =...

Course: MIT OCW 18.06 Intro to Linear Algebra by Strang 4th edt. Question: if a3,3 is 7, and the third pivot is 5, if we change a3,3 to be 11, then the third pivot becomes _________. If you change the a3,3 to ________ then there is no third pivot. At first I thought a3,3 had to be the actual...

Hi all,I would like to know how to calculate the force required to lift a flap (or drawbridge if you proffer) of known weight that is on a pivot and where the pull chain (let’s say it’s a chain) connects to the flap at a known distance from the pivot.I’d also like to be able to calculate the...

Here's a diagram of what I'm talking about: http://i.imgur.com/irgHuqq.jpg Basically, the only variable altered is the value for x. I tried googling for hours now, have read everything in my book relating to this topic, I still have absolutely no clue how to answer this. I tried studying sites...

After a wrist injury I had to stop lifting weights. This was annoying so I decided to make an arm brace that would transfer the weight of a dumbbell through my forearm rather than through my hand and wrist (with the help from my local metal works). I've now got the brace and its perfect, aside...

where can I find an example of a SIMPLE snippet of code used to create a pivot table?

Homework Statement A uniform horizontal beam of length 8.00 m and weight 200 N is attached to a wall by a pin connection. Its far end is supported by a cable that makes an angle of 53.0 degrees with the horizontal. If a 600-N man stands 2.00 m from the wall, find the tension in the cable and...

Homework Statement [/B] (i) Prove that dL/dt = 0 (ii) Find the relation between space part and 3-angular momentum vector (iii)Show that 3-angularmomentum vector is independent of pivot Homework EquationsThe Attempt at a Solution [/B] I'm not sure what part (iii) is trying to get at, but I...

Hi All. I am not sure if this is the right section for this but I will ask anyway. I am looking for a bolt that pivots midway like a hinge. I have seen them before but I don't know what they are called and cannot find any on-line. Alternatively does anyone know of a pivoting pipe? Can anyone...

Homework Statement A horizontal plank 4.0 m long and having mass 24.0 kg rests on two pivot points, one left at the end and a second one 1.0 m from the right end. What is the magnitude of the force exerted on the plank by the second pivot point? Homework EquationsThe Attempt at a Solution I'm...

Homework Statement Damped driven oscillator: ruler example. Suppose the ruler used in the classroom demonstration has a length of 12 and 13/16ths inches, a width of 1 ½ inches, is 1/16th inch thick with a density of 1.2 g/cm3. It swings from a pivot point ¼ of an inch from the top end. a) Find...