Questions tagged [free-body-diagram]

A pictorial device which analyzes forces present on any body with the use of vectors. Allows easier grasping of problems involving either objects at equilibrium or in motion. Can be used to predict presence of forces.

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1answer
52 views

What would be the consequences of action-reaction pair not being anti-parallel? [closed]

In the real world, action-reaction pair always make an angle of exactly at 180ᵒ. But what would happen if instead it was something like, say 179.9ᵒ. What would be the weird effects? I started off by ...
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Can static friction force alone make the center of mass accelerate in this example?

I came up with an idea of motion of ceter of mass the day before yesterday but couldn't find any solid answer for the cause of its motion. Take the example of a man (say of mass $50$$kg$) and a tank (...
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Consider the following figure. A man sits in a pan and tries to raise himself by pullingthe rope downwards [duplicate]

Consider the following figure. A man sits in a pan and tries to raise himself by pulling the rope downwards. Will he be able to raise himself up? Explain. I understand that it is not possible as like ...
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Swing lintel load with shorter string?

The Question: If I make the RED strings slightly shorter (what holds the swings) than the GREEN strings, would that mean that the RED "X" will have more weight/load vs. the GREEN "X&...
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6answers
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Cancellation of forces in feeling weight

If we are on the ground, Earth's center attracts us by $mg$ force and the ground also exerts $mg$ force in the upward direction. Those two forces cancel out. So there is no net force acting on us now. ...
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Problem with Action-Reaction pairs and gravity [duplicate]

There are lot of question on this site similar to this, but they give contradicting opinions. When standing on earth, my gravitational pull to the earth and earth's gravitational pull towards me ...
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1answer
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Dynamics of simple atwood machine [closed]

I am a student and need help with my homework: In this figure two masses m1 and m2 have been suspended from either side of the pulley m2>m1 As a result The blocks move with equal acceleration(a) ...
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Problem with gravity

Sorry if this question is dumb, but I don't seem to have a grasp on it. Suppose you are on a rock in space, with no external forces acting. The rock attracts you with a force given by $$F=G\frac{...
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Please explain the walking mechanism

When a person walks, he exerts a force on the road, lets say $F$, and the road exerts a force on the legs (friction), lets say $f$. Newton's third law says that $F = f$, so why is $f - F = ma$? Where ...
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1answer
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How to calculate kinetic friction coefficient given velocity and height?

The problem I am dealing with is about an object sliding down a ramp. I am only given the height of the top of the ramp to the floor, initial and final velocity, and weight of the object (in lbs). How ...
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Two astronauts in space

Astronauts on a tether Note that I have read this question but the answers do not make sense to me. Suppose there are two astronauts in space. And they are holding each other's one hand (we could also ...
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Why is the normal force and the tension force greater than the weight in these examples? [closed]

A pendulum is suspended form the roof of an accelerating train. If it stays in equilibrium with respect to the train then an observer at rest will find the bob accelerating with the train. He will ...
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The projection of the Newton law for a ball moving in an italic direction

if I want to push the bowling ball in a direction which is not parallel to the lane, then I need to make a Projection on the axes (the x axis is parallel with the width of the lane and the y axis is ...
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Spring system forces and displacement

I am trying to understand this system. A friend added to my confusion by stating the springs will not see all of Force B, they will only see all of Force B when the springs bottom out. To me, by ...
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1answer
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The direction of forces on a mass suspended between two vertical springs

I am trying to construct the free body diagram of a mass suspended by two vertical springs such I concluded that the weight of the mass exerts a force on the upper spring causing a tension force to ...
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Free body diagram and equilibrium of a differential-drive mobile robot

I'm trying to study the free body diagram of this differential-drive mobile robot: So i started considering just a straight motion (torque on the right wheel is equal to the torque on the left wheel) ...
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Masses connected to ropes through pulleys

How to know in which direction tension acts on pulleys where multiple masses are connected through multiple pulleys?
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Why do motorbikes turn out of the corner they are turning into?

I saw this clip of a motorbike race where every rider that was turning into a corner would turn the front wheel out, see image below. From a physics perspective, why do they do this?
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What should the coefficient of friction be if I don't want a box I'm trying tip over to slide?

Say I'm moving to a new house and my moving boxes are cubical and evenly packed. If I want to tip over/overturn one of the boxes by horizontally pulling on one of its upper edges, while balancing the ...
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6answers
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How can deceleration due to friction be positive?

If an object on a rough plane moves from A to B with negative acceleration -8m/s/s (due to friction). And back from B to A on that same surface, why is the acceleration then changed to positive? In ...
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1answer
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Tension in ring around a cone

This question is an extension of the following question Tension in a chain around a cone What I am not able to understand in the fbd is that why is the normal force acting outwards and not inwards ...
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2answers
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Forces on an oscillating skateboard

A half pipe of a skateboard park consists of a concrete trough with a semicircular section of radius 5m, I hold a frictionless skateboard on the side of the trough, pointing down toward the bottom and ...
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2answers
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Why can other people lift you up but you can't lift yourself up? [duplicate]

I know that the reason I couldn't lift myself up(without the help of any items or a pulley system)was due to that my force was internal and there is a reaction force. However, assuming that somebody ...
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1answer
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How to determine the tangential and radial component of the net forces on 2 particles connected by a rod?

How to determine the tangential and radial component of the net force such as the one in the following situation? Do the radial components always have to be in the direction of the rod? If so, why? ...
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3answers
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What is the force pair for the normal force? Clarification on Newton's 3rd Law

In the process of trying to wrap my head around Newton's 3rd law I've come across 2 definitive statements. Forces must occur in pairs Forces must act on different bodies This is confusing to me when ...
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How does Newton's third law hold during arm wrestling? [duplicate]

What happens when two people are arm-wrestling and one is winning? How is the torque that they apply on each other's arms different? And how do they follow Newton's third law of rotational motion? For ...
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Free Body Diagram w.r.t a rotating reference frame

According to my physics textbook, $1)$ When analysing the statics of a particle of mass $m$ from a reference frame which is rotating with angular speed $\omega$, we need to add a pseudo force known ...
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6answers
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Why does rotation happens about hinge point in a bar when net force acting on it are zero?

I have asked this question previously but not got any proper answer relevant to its free body diagram.Few are saying the body will not be in translational equilibrium as a horizontal force will appear ...
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Free body diagram

I recently learned how to draw free body diagrams. Suppose a block is kept on ground and we need to draw FBD of ground. One force would be reaction force by block on ground. Will we also include the ...
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1answer
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Why does rotation happens about hinge point in a vertical bar when net force acting on it are zero? [closed]

As we know that if the net external force on a body is zero its center of mass will be at rest and also rotation will happen about center of mass only but in this hinge and rod case it is clear by ...
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Can internal forces do work onto object(s) in a system? [duplicate]

I know that internal forces can't do work on a system but can it do work on the bodies in a system? For example, for a ball-earth system, even though gravitational force is internal, it still did work ...
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1answer
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Finding the Normal and Tension on a body on an inclined plane [closed]

Imagine an inclined plane with a body with mass $m$ on it. The body is connected to a rigid wall via string (Assume no slack and the string is parallel to slope). I want to find the normal reaction on ...
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1answer
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Is the force on the bob of a pendulum with respect to ground 0 at the bottom?

Kind of a silly question, but imagine there's a pendulum swinging that has some fixed length l and it's at some angle $\theta$, then with respect to us, the forces on the bob are: $$F_{rad} = mg \cos(\...
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Gardner Pushing A Lawn Mower Problem (finding the instantaneous acceleration)

I was able to solve this problem but want to solidify the concept behind it; A gardener pushes down along a handle of a lawnmower of 20 kg mass with a force of 150 N. The handle makes an angle of ...
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2answers
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Action-reaction

Suppose I have connected a string with a block and I'm holding another end of string and pulling with a constant force, say $F$. Now if I'm pulling this string by constant force $F$, this string is ...
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What happens when you pull in on a rotating object? [duplicate]

I was wondering how rotating objects would behave if we pulled them inwards DURING rotation? For example- If I was initially spinning a rock attached to a string in a uniform circular motion and then (...
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Say we have a conveyor belt with a pile of sand on top of it. What will be the maximum acceleration the belt can have before the sand start sliding? [closed]

I encountered this problem while studying for an exam later this month. I've drawn the force diagram: The coefficient of the rolling resistance is given as 0.50. I know the forces acting upon the ...
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1answer
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Tension, real or fake

It is a very simple problem. a massless rope but with friction is climbed upon by a monkey. I need to understand the working of forces here. Suppose the monkey is applying a force F on the rope. So ...
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1answer
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Why can we neglect the force of air (atmosphere) acting on the body in free-body diagram?

Let's say we have a body at rest. The forces acting on this body are: gravitational force and normal force. The pressure of the air is $1bar = 100kPa $ and lets assume that the surface of the ...
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How does tension pull at both ends? [duplicate]

How is tension pulling at both ends? Please explain either theoretically or by intuition. Ideally, answers would imagine the string as made of particles, and consider their free-body diagrams to ...
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Static friction problem [closed]

I think this is a pretty straightforward problem. “The minimum value of the coefficient of friction to prevent the system from moving” clearly refers to static friction. In this case static friction ...
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1answer
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Why forces come in pair? [duplicate]

Can a body 'X' apply gravitational force On a Body 'Y' without being itself acted by a gravitational force By 'Y'?
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Does buoyancy exert the same or different upward force on two dissimilarly shaped, but same volume objects?

Suppose I have two objects of exactly the same volume, one is a sphere and one is a cube. If the objects are completely submerged in water, is the upward buoyancy force the same or different on these ...
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Sliding arm problem, locking and singularity

I posted a version of this earlier but I feel like my problem was not very clear so I hope that this explains what is so confusing here. Shown in the image is a view from above, of an arm that's ...
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1answer
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How this equation is attained of the 3 forces of threads and the conductive spheres? [closed]

Currently I'm new to newtonian-mechanics, so I 've may been asking the trivial question. As shown in the above diagram, the each insulating thread has stretched the conductive sphere. The each sphere ...
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1answer
237 views

Why should the cord connecting the carrier to the hanging pan and passing through the pulley be made parallel to the horizontal box cover? [closed]

Why should the cord connecting the carrier to the hanging pan and passing through the pulley be made parallel to the horizontal box cover when doing the experiment in determining the coefficient of ...
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4answers
61 views

How to make an object at rest in a frictionless surface move at constant velocity?

let's imagine an object at rest in a frictionless surface (ignore air resistance too!) how can we make it move at a constant velocity? we need force right? If force is applied wouldn't it accelerate ...
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1answer
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What is the Difference Between Driving Force and Net Force? [closed]

I'm a bit confused with the question below. Particularly, I'm confused what the difference between driving force and net force is. For driving force, I easily find $$F_D = ma = 1000 \times 0.3 = 300$$ ...
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3answers
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Tension in massless rope

We are learning Newton laws in the University and were given the following problem: In the system described in the image, the man is pulling two massless ropes with a force of $F$ each. We are ...
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1answer
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(Climbing) rope diversion, different scenarios and forces

I went climbing with a friend of mine the other day. And To be able to toprope two different routes that where next to each other he set the diversion up like in the scenario B I sketched in the ...

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