# 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.

1,256 questions
Filter by
Sorted by
Tagged with
82 views

### How does a front wheel drive car accelerate?

In a front wheel drive car the friction acting on front wheel is in forward direction (say F1) and friction acting on rear wheel is backwards (say F2). So if the car accelerates forward F1> F2. ...
129 views

### Is a boat in water subject to Newtons 3rd Law

My boss has stated that balanced forces do not conform to Newton's 3rd Law and therefore a boat sitting in water does not conform, stating that the upthrust provided by the water is not a reaction ...
45 views

### Why is tension on both ends of rope equal and why is it only achieved at the middle of the rope when the mass is suspended by a ring?

I was told that when a mass attached to a smooth suspending wire by a ring shaped holder; after reaching the equilibrium position it would be exactly halfway across the wire and, tension on both ends ...
108 views

### Leaning ladder problem: minimum angle and frictionless floor

This video shows how to calculate the minimum angle for a leaning ladder considering static friction on the floor and a perfectly frictionless wall. I have 2 questions: If the wall had friction, ...
1k views

### Centrifugal Force Dilemma

While learning Classical Mechanics, I am confused on nature and application of centrifugal force. In my textbook, it is written that centrifugal force is a pseudo force that, depends on reference ...
52 views

### Confirmation on Potential energy of an object

I very well understand that a lot of people have asked the question "where does potential energy come from" on this site, but mine is more of clarification. If an object was propelled from ...
434 views

### Why do we neglect torque caused by tension of curved part of rope in massive pulleys?

In this MIT OCW lecture, the professor analyzes a block - massive pulley - block system as shown here: The analysis was easy enough to follow till this point: Here he says the only the end points of ...
82 views

### The time at which a car starts to skid on a rotating platform [closed]

I am trying to solve the following problem from the book "An Introduction To Mechanics" by Daniel Kleppner and Robert Kolenkow. $1.18$  Car on rotating platform A car is driven on a ...
83 views

### Finding contradiction in equations [closed]

Question:- In the figure shown, Coefficient of friction between the blocks C and B is $0.4$. There is no friction between block C and ground.The system of blocks is released from rest in the shown ...
34 views

### Elongation of a rotating string with mass attached to it

How can we calculate the elongation of a rotating string with a mass attached to it? We know, that the mass has a velocity of v and the other end of the string is fixed. Gravity is normal earth ...
36 views

### Normal Force when going INTO Unifrom Circular Motion

Thank you for taking the time to read and help! I've been thinking about what happens to the normal force when you're entering into uniform circular motion for the first time. I'm assuming a point ...
37 views

### How does surface tension prevent a pin from sinking?

Please explain simply how surface tension in water which as far as I understand is a force pulling the water molecules at the surface towards each other horizontally so how does that prevent a ...
92 views

### Problem regarding components of forces in conical pendulum

For the motion of conical pendulum we can write equations as $$T_{F}\cos\theta =mg$$ $$T_{F}\sin\theta=\frac{mv^2}{R}$$ $T_{F}$ represents tension in the string. $v$ is the velocity of bob at this ...
143 views

### Calculating the direction of friction on an inclined plane/Determining the fate of a round body on an inclined plane

Question: If a round object (say ring or a sphere) is kept on a rough inclined plane of inclination $\theta$ and coefficient of friction $\mu$ is such that it exactly balances the component of weight ...
55 views

### Body falling off a smooth hemisphere - simple but I'm missing something. What is it?

So here's the question that I'm stuck on. A particle slides from the top of a smooth hemispherical surface of radius $R$ which is fixed on a horizontal surface. If it separates from the hemisphere at ...
159 views

### Force analysis in a compound pulley system

At 4:56 of this video on compound pulley systems with the following schematic set up: The professor does a force analysis of the forces on the pulley A , and strangely (for me) , he finds that there ...
95 views

### Suspicious of Khan Academy's answer for a simple tension on a clothesline question [closed]

This is the question: 3 kg of wet clothes are hung on the middle of a clothesline with posts 6ft apart. The clothesline sags down by 3 feet. What is the total tension upon the clothesline? They give ...
73 views

### Newton 3rd law confusion [duplicate]

Why do things even move? I mean based on Newton 3rd law no matter how much force you exert on an object, it will always exert an equal and opposite force back to you. So why do things move?
123 views

### Why does normal force work?

I've got a lot of question about normal force. First, what causes normal force. Next, how do the object know how much normal force to exert. Lastly, how is this not an application of Newton 3rd law. ...
60 views

### Two stacked blocks with the upper block pulled with force $F$

I had to solve a question regarding the maximum force that can be applied on the upper of two stacked blocks for the blocks to move together (there is friction between the two blocks). I managed to ...
55 views

### Tension of string suspending a ball in Circular motion, given the mass of ball, radius and length of string [closed]

Ok so I have this question where a ball is suspended by an inextensible string and is caused to rotate in a horizontal circle which has its centre vertically below the point of suspension. What would ...
60 views

### What affects Buoyant force?

Why isn't buoyancy affected by the object immersed in water? I know that more depth means more pressure means more buoyancy. But based on Newton 3rd law, the water should apply a force back on the ...
93 views

### If I jump off the ground is the net reaction force doing work on me?

I know this may seem a basic Physics question but I still have problems understanding the 'work' concept. My muscles contract and they extend and push on the ground which in turn pushes on me . If I ...
54 views

### Mass sliding down a plane

Say we have a mass $m$ sliding down a plane with friction. Will the plane move too if it's mass is finite? Because the force of friction acting on the mass $m$ must react on the plane too but isn't it ...
75 views

### Free Body Diagram for a Body on a Smooth Inclined Plane [duplicate]

Consider a body of mass $m$ on a smooth inclined plane with the normal force and weight labelled as shown: Now, usually when the forces are broken into its components, we get an FBD like this: From ...
112 views

### Friction Block-on Block

Been studying block-on block problems. Attaching a picture of a sample problem. Pls do not answer the answer based on the picture, it is just a reference to the conception question to be asked. In ...
58 views

### Net force on links in chain?

Suppose there is a chain with 5 links in it where each link has a mass of $m=0.1kg$, and the chain is being accelerated upward at $2.5 m/s^2$. I want to find the net force on each link in the chain. ...
50 views

### Difference in weight while pulling weights

Let's say you are using a standard pulley gym machine to lift some amount of weight. If while you exercise you are standing on a weighing scale. What variations in weight if any would occur? Does it ...
68 views

### What density of an object of more than one substance affects the buoyant force?

If we immerse a sealed cup of a liquid in a fluid, what density is taken in consideration when it comes to the buoyant force, the density of the cup itself (the substance in contact with the fluid) or ...
68 views

### Analysis of a spring-block motion when the point of suspension is accelerating vertically upward

I was taught to apply a "pseudo force", [which is equal to mass × acceleration (of point of suspension)] in the direction opposite to the point's acceleration and then proceed the way I ...
100 views

### Counterintuitive tension: weight attached to block on table via a pulley?

A problem in Halliday-Resnick's "Fundamentals of Physics" poses the question of finding the tension in a rope connecting two blocks of masses $m$ and $M$. The block with mass $m$ is hanging ...
101 views

### Intuitive explanation of Archimedes' principle? [duplicate]

https://en.wikipedia.org/wiki/Archimedes%27_principle The wikipedia entry for Archimedes' principle (buoyant force = weight of fluid displaced) has interesting formulas explaining why it's true, but ...
83 views

### Free body diagrams for dummies?

I'm self-studying physics. What are some good books/online resources to practice making free body diagrams for learning classical mechanics?
227 views

### Newton's Third Law is just wrong, can you see why? [closed]

For every action there is an equally opposite reaction is flawed. Can you identify why? The answer is simple enough and its simplicity makes it very hard to see, can you?
43 views

### When we push a box, the box applies an opposite force on my hand, but why does my hand move with the box as I push the box if the net force of it 0? [duplicate]

When we push a box, the box applies an opposite force on my hand, but why does my hand move with the box as I push the box if the net force of is 0?
112 views

### When we push a box, the box applies an opposite force on my hand, but why does my hand move with the box as I push the box if the net force of is 0? [duplicate]

When we push a box, the box applies an opposite force on my hand, but why does my hand move with the box as I push the box if the net force of my hand is 0? What is happening?
83 views

### Why is $mg$ split into components instead of the tension in vertical uniform circular motion?

I am a beginner physics student. I am trying to prove that the magnitude of the tension varies sinusoidally as an object P travels around the circle or something of that sort. Thus, I am evaluating ...
50 views

### Question regarding friction

To make an object on ground start moving, the force applied (lets call it $f$) must be greater than $\mu_sN$, where $\mu_s$ is the coefficient of static friction between the object and the ground, and ...
203 views

### Why did water not drip form this small bottle?

I will explain what I have done and my observations. I took this bottle and added water into it. 1st time , 25 percent , then 75 percent and then 100 percent of water was filled in the bottle. Yes , ...
133 views

### A ball held by two strings is rotating around a pole. Find the tension in each string [closed]

The problem is the following: I notice that this is an equilateral triangle meaning that the angle below and above the dotted horizontal line is $\frac{\pi}{6}$ rad. I then draw a force body diagram ...
936 views

### Why don't we consider centripetal force while making FBD (free body diagram)?

Consider a situation where a block is kept on a wedge which is further kept on a surface which rotates with $\omega$ the FBD for the same My question is why dont we consider centripetal force in fbd? ...
55 views

### Implications of massless pulleys in Atwood machines

Consider the double Atwood machine below: I understand the classic approach to a solution for the acceleration of each mass involves setting the tension in the upper string equal to twice that of the ...
2k views

### Apparent weight in the elevator

If an upward force was applied on an object which was at rest, the magnitude of the normal force decreases, whereas, in an elevator which is undergoing an upward acceleration, the magnitude of the ...
48 views

### FBD for Cylinder in water , acceleration of water and why is $P$ perpendicular force? [closed]

Here, we have accounted two kinds of pressures according to my book. One is atmospheric pressure and other is pressure exerted by liquid of density $f$. My questions are that first we say that ...
42 views

### Is this constraint equation written right here?

This is a constraint equation he has written here. This is a trick to solve constraint equations faster. Now he has made a equation that a2 ( acceleration of 2kg block) and a1(acceleration of 1kg ...
43 views

### Confusion in constraint relation question method

There are two ways I found constraint relations are written here.Not able to understand how is that one done. 1 way of doing it.Here we considered the displacements of pulleys and block form one fixed ...
51 views

### What is the speed at which the wedges recede? [closed]

A plank is held at some height between two smooth wedges of inclination $45^{\text{o}}$. If the plank moves down at a speed $v$, at what speed will the wedges recede? Could someone give me a hint how ...
46 views

### Measuring the correct mass or weight of an object in the presence of atmospheric pressure?

I know due to atmospheric pressure the weight of an object increases, but when we take measurements we do not omit the weight of the column of air above it. So, doesn't it affect the accuracy of our ...
### While a solid cylinder of radius $R=3m$ and mass $M= 1kg$ rotates at an angular velocity $\omega=29 rad/s$ it touches a frictional corner [closed]
--- The friction coefficient =0.1 how many revolutions does the cylinder make until it stops? So it's obvious that we'll first have to use the relation $I\alpha=\tau (about centre)$ and that the net ...