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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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Why is the force of gravity the net force? [on hold]

The first image is the diagram** in this FBD, use Fg on m1 as its net force (not concerning the friction). why do you not subtract the tension force in Mass 1?
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1answer
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Newton's Third Law Slope [on hold]

I know Newton's Third Law says there is an equal and opposite reaction when you apply a force. Consider the diagram of an object on a slope above. What is the force the object is applying on the ...
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3answers
69 views

Force due to motion around Sun [closed]

Think of one person on earth named A . Ignoring Earth for a second, I can imagine him moving around the Sun due to which he should always feel some acceleration towards Sun (Centripetal Force) say F1. ...
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1answer
34 views

Kinetic energy of a yoyo

Consider the yoyo above: The yoyo is constructed from two heavy disks of radius R connected by a light axle of radius r , as shown in the figure below. The total mass of the yoyo is M and its moment ...
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2answers
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Would equal balance at same height when hung on a balance?

This is based on a question from the gravitation course on Brilliant. As you can see in the diagram below, we have 2 weights hung on a pulley. It is given that: Neither one accelerates when you let ...
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3answers
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How to make a object stay under water?

How to make an object submerged under water? Neutrally buoyant? Thank you
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1answer
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When do we illustrate inertial forces on inertial frames of reference?

I came across two practice questions wherein an object was attached to an accelerating vehicle, yet only one of these cases required an inertial force to be illustrated on the object's free body ...
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1answer
86 views

Why isn't there an analogy for $\vec F = \frac{d \vec p}{dt}$ for $f_{mag}$?

While analysing a force changing the motion of a particle, I always like to imagine the simplest case I can think of: an elastic collision of a ball with a block, and then ask myself in what terms ...
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2answers
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Free body diagram for a non-fixed (movable) ramp, with a box at rest on top of it

I'm having trouble figuring out how this free body diagram would look. The question involves a block at rest on a ramp, which is in turn at rest on a table. All objects are made of the same material, ...
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4answers
127 views

Does Archimedes principle account for depth?

The principle states that the upthrust acting on an object is equal to the weight of the fluid displaced by the object. However, this to me suggests that no matter how deep an object is immersed in ...
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3answers
101 views

What will be the compression of a spring if two different forces act on it? [closed]

QUESTION What will be the compression in this picture? Many problems relating to springs are when one side of the springs are fixed and the other is free to deflect. But what happens when the spring ...
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5answers
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Is the normal force in the $x$-direction equal to $mg$ for a sliding object? [closed]

At point A, is the normal force in the x direction equal to mg? When the object is going down I imagine $N_x$ decreasing and $N_y$ increasing until point B where $N_x = 0$ and $N_y = mg$. That's why ...
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Why doesn't Newton's third law mean a person bounces back to where they started when they hit the ground? [closed]

Why doesn't a person bounce back after falling down like a ball? If we push a person and he falls down then why doesn't he come back to its initial position. Although according to Newton's 3rd law of ...
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1answer
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5.61b University physics with modern physics [closed]

$$ \sum F_{y} = 0 $$ $$ \sum F_{y} = T_{1y} + T_{2y} - mg $$ $$ mg = (4400N)\sin{60} + (4400N)\sin{40} $$ $$ mg = 6640N $$ Why is this wrong? solution $T_{1x}$ has to be equal to $T_{2x}$ $$T_{1x} ...
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2answers
84 views

Forces on accelerating massless pulley [closed]

Consider a massless pulley with string passed over it and connected to two masses. The string holding the pulley is pulled vertically upward with force F. My question is what would be the tension in ...
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2answers
129 views

Tension in a string, at an angle [closed]

This was a question on a mechanics exam. Part i wants me to assume that the tension in both parts of the string is the same. Even though I got the correct answer( 18.9N) by assuming so, I don't ...
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2answers
50 views

Net force acting on a box in this diagram

The 27-kg slider block is moving to the left with a speed of 5 m/s when it is acted upon by the forces $F_1$ and $F_2$. Neglect friction and the mass of the pulleys and cords. The net force acting on ...
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2answers
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Where does the centripetal force come from? How to calculate?

When a bucket filled with water rotates, the water surface will be parabolic( I mean the water is rotating and the water surface is parabolic). Where does the centripetal force of a particle of water ...
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1answer
30 views

How Newton's third law works in a system with external force on it?

I got a little confused about Newton's third law. So if there is a system of two particles that interact mutually with each other and also this system is itself as a whole is acted upon by some ...
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1answer
48 views

Variation of Tension in a rope [closed]

In the 1st picture we consider the tension in the rope to be the same on both the sides. However in the second picture we take it to be different. Why? If we have to consider a general case then why ...
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2answers
59 views

Confused about forces acting in this simple statics problem

I'm trying to solve this statics problem to find the internal tension that results, in each member: It shows 3 idealised weightless rigid members hinged in a vertical plane, in an isoceles triangle. ...
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0answers
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How do I draw a diagram of the forces that create the “barndoor effect” (unbalanced torque) in rock climbing?

I have been asked to use a diagram that illustrates when a flag in rock climbing is necessary. I have no idea how to draw the forces involved in torque.
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1answer
47 views

How do I know whether members are in tension or compression when using Method of Sections?

So we started doing structural analysis in my engineering class lately, and are doing trusses. However, I'm not quite sure how method of sections works conceptually. I'm getting the right numbers, but ...
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2answers
63 views

In which direction does the pseudo force act?

The point O is where the small mass is attached. I'm trying to find out the minimum velocity that should be given to the mass so that it can complete a full circle but if the fixed point is ...
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3answers
58 views

Which fundamental force acts while pushing a book on the table? [duplicate]

I know that this is a total novice question. When I push a book from point A to point B, a force is applied by me. The book has mass and some acceleration was also achieved in this example. I recently ...
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3answers
875 views

Why do objects rebound after hitting the ground? [duplicate]

When an object, say a shoe, falls from a height (under the influence of gravity), it rebounds after hitting the ground. For an object to move upwards, it requires a force to overcome its weight. When ...
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1answer
31 views

In fig we have a block (shape $A$) that a rod is connected to it (shape $B$)

In fig we have a block (shape $A$) that a rod is connected to it (shape $B$) let that this system is stationary . Now I know that free body diagram is : Thus $$A : \vec{i} :T_{BA}=f_{s}$$ $$A : \...
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1answer
51 views

Mathematical expression of impulsive forces during a collision

I'm facing with problem regarding collision between bodies. Specifically, I need to understand the impulsive forces that arises during a collision. Sometime ago, I posted two questions (this and this) ...
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1answer
45 views

Downward force applied on a wedge

If a vertical (downward) force is applied on a wedge (on the sloping surface) then what would be its component in horizontal direction? It should be zero as the angle between them is 90 degrees. But ...
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1answer
45 views

Formula for would something fall over or not?

Let's say I have a 10cm x 10cm x 50 cm wooden stick that weights 5kg total. The 10cm x 10cm base is touching the floor and it protrudes from the floor 50cm which is the height of the stick. Based on ...
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1answer
64 views

Stupid pulley question [closed]

I started self-studying physics and it's been 15 years, since I took basic mechanics in college. It seems to me that I'm unable to figure out how to rigorously derive from Newton's laws how a basic ...
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2answers
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Question about pulley

I am wondering if the tension in the ropes in this situation is the same. Doesn't it matter if the other rope is pulled at an angle? Does this change the tension in the rope? For example if at one ...
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1answer
42 views

Derivation of acceleration and tension of pulley system [closed]

On this website I am considering the question that goes along with figure 30. I am going to assume downwards is negative and rightwards is positive (not to confuse upwards as the website says). The ...
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1answer
56 views

Does the rope stretch when the pulley of Atwood's machine is accelerated?

Let's say I've an Atwood's machine in which I have two point masses which are different. Now, when I accelerate the pulley, the two masses accelerate at a different rate which can be shown by ...
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4answers
70 views

Tension at extreme of a rotating rope of mass $m$

A uniform rope of mass per unit length $\lambda$, length $\ell$ is attached to shaft that is rotating at constant angular velocity $\omega$. Find the tension in the rope as a function of distance ...
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1answer
47 views

Gravitational force on a rope

If we have a rope fixed to the ceiling. How much gravitational force will the rope experience? Let's suppose the mass is $m$. Well the obvious answer is $mg$. But doesn't the part that is ...
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2answers
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Weight of a person sitting on a spring kept on a weighing machine. What is the reading shown? [closed]

In the above image, what would the scale reading be? Let scale reading be $R$. I was taught that the scale reading will always be the Normal force. Thus imagining the compression of spring to be $x$ ...
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1answer
22 views

Derive an equation for the minimum vertical distance needed by the string connected to masses to start accelerating [closed]

It would be helpful if someone could help with this problem. Let us consider a mass m1 on a horizontal surface which has friction between the mass and the surface. It is attached to another mass m2 ...
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1answer
48 views

How can I measure some forces in this experiment…? (statics)

Math and statics weakling here trying to do some... math and statics. I have an experiment where I'm trying to measure forces along 2 axes. I currently have a setup that I think might give me the data ...
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1answer
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Problem on force components [closed]

In this problem, is the direction of tension(725N) shown in the free body diagram correct? Wouldn't such a direction lead to compression instead of tension.
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1answer
38 views

How is the normal force on a banked track larger than gravity?

The formula of the vertical force of an object that is not accelerating up or down on a banked curve is: Ncos(θ) = mg There is also a centripetal force component which shows that the normal force is ...
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2answers
48 views

Will the motion in both systems be same?

In my book, the discussion in SHM is mainly about a mass hanging vertically from a spring. But there are some exercises which contain questions which involves a mass attached to a spring and the whole ...
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1answer
62 views

Why a rope grabbed by a single end seems to follow the hand that grabs it?

Context I am thinking about the physics of the movement of a rope in the context of a person running and grabbing a rope in one hand (the other end is "free", there is nothing attached). When the ...
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2answers
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What is the force of friction on the body? [duplicate]

This might seem like a stupid question, but my instructor could not give a straightforward answer. If a body is kept in contact with a completely vertical surface i.e. right angle to the ground, and ...
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15answers
6k views

Which specific law of physics is broken by the “double jump”? [closed]

So, there's a cliche in computer gaming known as a "double jump". This can be described as: A character jumps from a solid surface, and then is able to extend their jump by carrying out the jump ...
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2answers
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Work done by friction in this Case

So there is an elevator going down with a constant and the block does not slip on the wedge. We have to find the work done by friction in time t. So the answer given is $-mgvt\sin^2\theta$. What I ...
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2answers
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Why cannot we go in outer space with constant speed?

Sorry if this question is very childish for experts here. This was the question I had in school and years later it has resurfaced. I did some google search but getting the same equations of ...
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1answer
63 views

What is the direction of the “normal force”? [closed]

What would be the direction of normal and friction forces when a rod is falling which was initially kept upright on a table?
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3answers
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Friction while Rolling Without Slipping

This is an excerpt from an elementary Physics textbook ("Fundamentals of Physics" by Halliday), which describes what happens when a wheel that is "rolling without slippging" doesn't have a constant ...
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1answer
66 views

Surface friction and Newton's third law [duplicate]

My question is regarding a specific case displaying Newton's third law. In the diagram below, a man is shown exerting a force on the wall, which in turn causes an equal and opposite reaction force ...