Skip to main content

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
0 votes
2 answers
34 views

How would I calculate the force of friction between an RC car and a carpet?

I'm working on a physics project where I aim to demonstrate how different surfaces impact the velocity and acceleration of an RC car due to friction. How can I calculate the coefficient of friction ...
Dominic Pham's user avatar
10 votes
3 answers
1k views

How does this tensegrity table work?

I have assembled below a desk toy which seems to defy laws of physics at first glance (objects can be placed on top of it up to a certain limit, since it is already under strain). The toy is in fact ...
Tom's user avatar
  • 1,338
-2 votes
0 answers
37 views

Constraint motion question [closed]

I found difficulty in solving this question. I tried setting up the equations of motion and free body diagram like such [insert math or equations and key concepts], and computed the result [enter ...
Jai Mahakal's user avatar
0 votes
4 answers
135 views

Question about Newton third law especially the reactive force [closed]

Sorry for not giving much elaboration , here is a more detailed question,I have a confusion with the reactive force in dynamic cases (not in statics). Imagine there is a box and a person (both have ...
Mohamed Ibrahim's user avatar
1 vote
2 answers
71 views

Why is work done by normal force 0 here?

In solving this problem from Kleppner and Kolenkow, the (total) work done by the reaction force b/w the cube and the large block is taken to be 0 and I cannot seem to rationalise this. Clearly, the &...
Vulgar Mechanick's user avatar
0 votes
4 answers
94 views

A person is pushed forward in a bus when brakes are out because of inertia or pseudoforce?

When a bus moving uniformly and suddenly brakes are applied, the person will be pushed forward. The explanation given in textbooks is inertia but cannot it be explained by the concept of pseudoforce ...
Parsec's user avatar
  • 17
-1 votes
0 answers
33 views

Double Atwood's Machine Problem [closed]

I'm trying to find the Acceleration of each mass. so far I managed to find a1 (hopefully) can someone validate my work so far? (except the neg sign I missed on the final answer)
mst's user avatar
  • 19
0 votes
1 answer
28 views

Friction acting on a moving car

I am trying to understand the nature and direction of friction force acting on from the ground a car driving up an incline. I was thinking about a simple situation where a car of mass $ m $ is driving ...
Lukasz Skowron's user avatar
0 votes
0 answers
37 views

Classical mechanics pulleys, Something is wrong with my workings out, non-convergent sum? [closed]

Find the acceleration of any mass for this type of system. At the lowest pulley there are two masses connected, $m_n$ and $m_{n'}$. I having a hard time tackling the finite problem but the solution as ...
mr chap's user avatar
  • 111
1 vote
4 answers
268 views

Why is resolving vectors in some ways WRONG?

The following question is from "Concepts of Physics" by H. C. Verma. A man has fallen into a ditch of width $d$ and two of his friends are slowly pulling him out using a light rope and two ...
Gaurav Batra's user avatar
0 votes
4 answers
42 views

How does each team pull the opposite team with equal force in tug of war by Newton's third law? [duplicate]

How does each team pull the opposite team with equal force in tug of war by Newton's third law? Is it even related to the third law? If a man A on right pulls the rope with 50N force, is it necessary ...
Gaurav Batra's user avatar
2 votes
5 answers
487 views

Why does the block move if the net force is zero?

In free space an end of a rope is attached to the left side of a block, the other end is freely floating. An astronaut (on the other side of the block where the rope isn't) pulled the block by 5N ...
Gaurav Batra's user avatar
0 votes
0 answers
36 views

A body on which the net force is zero but is still accelerating with respect to the question below [duplicate]

First of all thank you so much for reading, I was trying to solve the question below from "Concepts of Physics Vol1" by HC Verma. What I was most interested in was the second part, "...
Gaurav Batra's user avatar
-1 votes
1 answer
42 views

Question about the geometry of the normal force [closed]

Let's say a man is pushing a box over a ramp with angle $\theta$ with the horizontal. By opposite adjacent angles, I think the normal force would be $mg\sin\theta$ why is the normal force $N = mg\cos\...
samsamradas's user avatar
1 vote
1 answer
48 views

Confused about this free body diagram

In this question I was confused when I saw the solution Why do we make the FBD like the right one instead of the one on the left. Isn't the mgcostheta acting on the wedge an external force? I would ...
Toshiv's user avatar
  • 13
0 votes
4 answers
67 views

What are internal and external forces?

what is internal and external force? How do I decide what forces are internal and external? in work-energy theorem and conservation of mechanical energy, do we consider internal, external, or both ...
android's user avatar
  • 69
3 votes
3 answers
259 views

Infinite force paradox in pulling a car out of mud

Consider a car stuck in mud. A way to pull the car out would be tying a rope with a tree and pulling on the rope perpendicularly, at the midpoint: This works well as it magnifies the force depending ...
Nightwing's user avatar
  • 267
2 votes
1 answer
47 views

Motion of a particle falling along a rough circular rail

I’ve recently been reminded of an old disagreement I had with a very well-respected professor at my university back in my student days, I was tutoring for one of his courses and had been assigned the ...
LvdT's user avatar
  • 183
0 votes
1 answer
70 views

Reasoning behind failure of string constraint in acceleration but not velocity

As I understand it, the string constraint used in mechanics with an ideal string is derived from the fact that the length of string always stays the same (provided it is under tension and not slack). ...
Codeman's user avatar
0 votes
2 answers
46 views

Does the law of the lever apply to all levers?

I recently posted a question involving the law of the lever, and I realized I was unclear on what it meant. I understand that, for a lever to be balanced, the effort force times the effort arm must be ...
user386598's user avatar
0 votes
1 answer
29 views

Comparing reaction force in uniform circular motion [closed]

in this diagram an object is moving in uniform circular motion in given trajectory which is a part of a circle. It's asked to find a point where the normal force is the least. I have shown my solution ...
f3rhd_'s user avatar
  • 55
0 votes
1 answer
26 views

What exactly means when a car is skidding or an object is slipping/sliding in terms of friction?

what does it mean when a car skids? which type of friction acts on the wheels? what does it mean when a car is not skidding? for both these questions, how do we frame the force equation and which ...
android's user avatar
  • 69
0 votes
1 answer
56 views

Why doesn't a part separated from an accelerated body accelerate anymore?

Suppose, a force $F$ is applied on a body of mass $m$ for which it gains acceleration $a$. So, in this condition every single point (Considering only atoms and molecules) has the acceleration $a$. But ...
Debanjan Biswas's user avatar
6 votes
4 answers
201 views

Static friction with ground when two blocks have different coefficients

Suppose I have two blocks of masses $m_1=m_2=m$ with coefficients of friction $\mu_1=1$ and $\mu_2=2$ respectively with the ground that are in contact. If I apply a force $F=2mg$ to $m_1$, what are ...
Vulgar Mechanick's user avatar
0 votes
1 answer
85 views

What exactly is the normal force?

Let $T := 24\times 60\times 60 [s]$. Let $r [m]$ be the radius of the Earth. Let $g [m/s^2]$ be the gravitational acceleration at the equator. Let $m [kg]$ be the mass of Mr. A. Mr. A is standing on ...
佐武五郎's user avatar
1 vote
4 answers
80 views

Should a box on a surface have an even number of forces?

My teacher showed us the following diagram. He said: When a box is placed on a surface, a weight force $W = mg$ acts on the surface, to which, the surface applies Normal Reaction $N$ on the box so ...
user438454534's user avatar
0 votes
2 answers
95 views

What are the acting forces in the tug of war problem? [closed]

My intuition says that person 1 exerts a force $F_{1}$, but it's not exerted on person 2, rather, it is exerted on the rope in between. So far so good. From Newtown's third law, the rope exerts a ...
Jack's user avatar
  • 847
0 votes
1 answer
41 views

Static friction, no work

Imagine a ball rolling without slipping on the floor. Then the force of static friction has non-zero torque, so why it doesn't change the overall energy of the ball?
Piotr H's user avatar
  • 23
2 votes
2 answers
538 views

According to Newton's Third Law why is there a difference in movements between collisions of different mass (please read description)?

When an object of some mass hits and rolls towards another stationary object of the same mass, the ball that was rolling stops. However, if we use the same ball from that scenario, and roll it at the ...
John's user avatar
  • 23
1 vote
2 answers
117 views

Calculating the net forces in multi-mass dynamic system

I am trying to figure out a generalized method for finding the net force of each mass in a multi-mass dynamic system. We have learned methods in highschool but those don't work for more complex ...
Khalil Burns's user avatar
1 vote
1 answer
45 views

Normal force and when does it cancel out

If i have this box, making a turn and there is tennis ball inside, then how in terms of forces can the tennis ball stay how i drew it, all the way around the circle? What provides the centripetal ...
Safa yousif's user avatar
0 votes
1 answer
60 views

Proof regarding $ \sum\vec T_i\cdot \vec a_i=0$ this relation for a pulley mass system [closed]

How to prove that for a system containing more than one pulley and more than two masses this relation will hold. $$ \sum\vec T_i\cdot \vec a_i=0$$ where $T_i$ and is the tension acting on the $i^{th}$...
Skdmg's user avatar
  • 103
7 votes
7 answers
3k views

How do objects reach terminal velocity?

I understand the basics of this principle: the force of gravity acting downward on an object becomes equal to the air resistance acting upward on the object because as the object speeds up, air ...
user386598's user avatar
16 votes
8 answers
4k views

Do hanging masses contribute to the mass of the entire system?

Consider the pedagogical machine on a frictionless surface from the book by Kleppner and Kolenkow: When we are talking about the acceleration of the whole system, do we use $$F=(M_{\text{net}}\text{ ...
alam's user avatar
  • 169
0 votes
1 answer
39 views

How this equation arises in free body diagram of rolling motion? [duplicate]

Concerning rolling motion for a sphere (without slipping) I have read somewhere that here solving using free body diagram we can write$$F-f_r=ma_{com} \space\space\space\space(1)$$ where $a_{com}$...
SHINU_MADE's user avatar
0 votes
1 answer
31 views

Newton's Second law for stacked blocks

I have a slight confusion regarding the application of Newton's 2nd law in a situation where there are two blocks, of mass $m_1$ and $m_2$, which are stacked on top of each other and placed on a ...
ethanolex's user avatar
0 votes
1 answer
55 views

Understanding normal reactions on a ring

I need to find all the normal reactions and the frictional forces acting on the ring to keep it in a state of equilibrium. It's given that a force $\vec{P}$ is being applied by a finger on a ring that ...
user438454534's user avatar
2 votes
4 answers
1k views

Can't Newton's Third Law be proved from the other two?

I've been thinking of this proof of the 3rd law from the 2nd law. The proof is as follows. We have a compound object made of two smaller objects, each of mass km and m so that the total mass is (k+1)m....
Zamil Hoque Siddique's user avatar
0 votes
1 answer
52 views

Direction of static friction in wheel [closed]

If a wheel is rolling right, that means the static friction on the stationary point that touch the ground is pointing left. That creates the torque that moves the wheel right. But if that stationary ...
Dor's user avatar
  • 11
1 vote
2 answers
59 views

A block experiencing a constant force collides with a stationary block

If a constant force is exerted on a block 'A' on a frictionless surface and if it collides with a stationary block of a lesser mass on the same surface (let's call it block 'B') then upon the ...
Rohan Rajasekar's user avatar
0 votes
1 answer
53 views

String pulling sides of a triangle inwards: Force acting on each side?

Referring to the image above: The black lines are ONE continuous string whose ends are where the red thing is. The red thing can tension the string and can measure the force used to tension the ...
aehhhhmm's user avatar
0 votes
0 answers
50 views

Tension in a falling rope attached to a support

I came across this question and thought it was fairly simple. Here is what I did: The rope is slack at the lowest point. At t = 1, this point is at 2.5m below the support. we can say the tension is ...
Shreyas's user avatar
0 votes
0 answers
28 views

When we are on the ground do we still accelerate with 9.8 m/s²? [duplicate]

Do we accelerate with 9.8 m/s² when we are on the ground , if so why we do not fall inside the eart . How is the net force is zero , how many real forces acts on the body ?
Pranjal's user avatar
-1 votes
1 answer
64 views

Tension while hanging from a bar [closed]

Consider angle = $x^ \circ$. Then according to a free-body diagram $$mg=2T\text{cos}x$$ and $$T=\frac {mg}{2\text{cos}x}$$ So I know $x$ is mostly $0^ \circ$. But what about at $180^ \circ$? Is it ...
s8r9y1's user avatar
  • 1
0 votes
1 answer
36 views

Why is normal reaction on a pulley not equal the weight hanging below it?

Pulley and string are all massless => hence, I consider only the net downward force applied to the pulley by both the masses under gravity. Why is the normal force on the pulley not equal to the ...
Sasi Kiran's user avatar
0 votes
1 answer
92 views

Goldstein Mechanics, Ch.1 Derivation 3

In the Derivations sections of the First chapter of Goldstein's Classical Mechanics, we find the following question: Suppose a system of two particles is known to obey the equations of motion, Eqs. (...
VinceWizd's user avatar
0 votes
1 answer
35 views

When lifting a block with your hand held flat, are both a normal and applied force present, or just one of them?

Today in class we were reviewing free body diagrams and we encountered a problem where an individual placed a block on their hand with their palm facing the ceiling. This is just a simple free body ...
James 's user avatar
0 votes
1 answer
46 views

Rope over an un-ideal pulley in an Atwood's machine

Please consider a pulley with a taut rope over it and two objects (with different masses m1 and m2) hanging on each side. The pulley is not negligible - it has a mass Mp. In the solution to a problem ...
Aviv Cohn's user avatar
  • 605
2 votes
2 answers
87 views

Where do exerted forces come from?

I think my confusion stems from this: if a book is resting on a table I understand that the force of gravity acts on the book and as it is in equilibrium, the table exerts a force equal in magnitude ...
lemonmeringue 's user avatar
0 votes
3 answers
147 views

How is Newton's 3rd law applied in rocket propulsion?

I'm really wanting to get into physics more and I've had this question for a while. I do know a bit about rocketry as I think it's pretty cool but I'm still struggling to understand how Newton's 3rd ...
StrangeJmaster's user avatar

1
2 3 4 5
38