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.

Filter by
Sorted by
Tagged with
1
vote
2answers
49 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 ...
0
votes
1answer
24 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 ...
0
votes
2answers
34 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, ...
5
votes
5answers
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 ...
-1
votes
3answers
47 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 ...
5
votes
2answers
399 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 ...
0
votes
1answer
35 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 ...
0
votes
1answer
23 views

Relations between string tensions, involving acceleration and pulleys [closed]

What goes on here is that I have acceleration for both m2 and m1. By logic, any change in position of m2 doubles the change of position for m1, since it pulls the left pulley by that amount, and it ...
1
vote
1answer
80 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 ...
0
votes
0answers
34 views

How to find the force of gravity on this copter arm? [closed]

Here is the image we're given So the force of gravity points the copter arm straight down. We are told that the angle the copter arm makes with the horizontal is $\theta$. We are also told that the ...
0
votes
0answers
36 views

Torque hidden in FBD door hanging with two hinges [closed]

Is the FBD for a door with two hinges correct? If it is correct, why is the sine component of the gravitational force on the center of mass not labeled as a reaction force from the hinges? Here is ...
0
votes
1answer
29 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 ...
0
votes
1answer
29 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 ...
0
votes
6answers
93 views

A man lifts a 50 kg object and stand on a weighing machine. How much does the machine read if he weighs 50kg? [closed]

Will it weigh 100kg or less than 100kg. This confuse me because I exert an equal upward force against the object to lift it. The weighing machine can sense only the net downward force acting on it ...
0
votes
2answers
26 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 ...
1
vote
3answers
62 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 ...
5
votes
4answers
105 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 ...
0
votes
1answer
37 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 ...
1
vote
2answers
86 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 ...
2
votes
1answer
74 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 ...
-1
votes
3answers
60 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?
1
vote
3answers
93 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. ...
1
vote
1answer
40 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 ...
0
votes
3answers
38 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 ...
0
votes
2answers
46 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 ...
0
votes
2answers
51 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 ...
1
vote
2answers
48 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 ...
4
votes
2answers
56 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 ...
0
votes
2answers
48 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 ...
1
vote
1answer
38 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. ...
1
vote
3answers
37 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 ...
1
vote
3answers
49 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 ...
1
vote
2answers
64 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 ...
2
votes
3answers
59 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 ...
1
vote
2answers
55 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 ...
-3
votes
2answers
69 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?
-13
votes
1answer
107 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?
0
votes
1answer
35 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?
1
vote
2answers
60 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?
2
votes
1answer
57 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 ...
1
vote
1answer
37 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 ...
6
votes
2answers
97 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 , ...
0
votes
2answers
48 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 ...
2
votes
6answers
661 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? ...
2
votes
2answers
42 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 ...
11
votes
8answers
1k 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 ...
2
votes
1answer
38 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 ...
1
vote
1answer
32 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 ...
1
vote
0answers
35 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 ...
0
votes
1answer
46 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 ...

1
2 3 4 5
23