# Tagged Questions

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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### Acceleration of a pulley system

The figure above shows a pulley system consisting of 3 masses ($m_1$, $m_2$ and $m_3$), a homogeneous wheel (radius R, mass M) and 2 massless pulleyes which are connected by a massless rope. Mass $m_1$...
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### Conceptual doubt in Tension force

I recently studied that Tension in a string is a kind of force originated from electrostatic attraction between the atoms of the string in which the force is originating. My doubt was that: Assume ...
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### Frictional force on an inclined plane with applied force = Mgsinx - Mgcos x?

I was reading Introduction to Classical Mechanics (Morin) recently and came across this example, which said that the friction force (marked $F_f$) is $Mg\sin\theta - Mg\cos\theta$. However, I can't ...
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### Friction to just move the blocks [closed]

Two blocks each of mass $m$ are placed on a rough horizontal surface and connected by mass-less in-extensible string as shown.The coefficient of friction between each block and ground is $\mu$ What ...
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### Free Body diagram force question

Here is a semicircular track and the ring of mass $m$ sliding on it. The ring is attached to spring of force constant $k$ and the elongation $x$ at that point.I just wanted to know that just as I ...
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### Multi-particle systems with different accelerations

While taking a system of multiple bodies under motion, is it possible to take those bodies in a system which have different accelerations? Say there are 3 particles having acceleration along x,y and z ...
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### Does a scale weigh a bee flying inside a box?

This question is very similar to this one or even this one except some minor differences. The box is much larger than the bee. The box has no top cover. The bee is flying still in the middle of the ...
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### Accelerated frames conceptual doubt [closed]

This thing has baffled me for a very long time and therefore I had to ask it here. I was thinking about accelerated frames. Lets assume I am sitting in an elevator going upward with some acceleration ...
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### Newtonian mechanics, block on conveyor belt [closed]

The coefficient of friction $\mu$ between the block and the conveyor belt is $0.3$ and the belt is moving with a speed of $6m/s$ when a block is dropped onto it from rest. Find the time when the ...
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### Cable wakeboard raley

Illustration of the problem: http://www.youtube.com/watch?v=OWRixptJaRo The non physics solution: http://www.youtube.com/watch?v=FRwHcJjfCR4 My first approach to learn this was to follow youtube ...
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### Confusion with Newton's third law

“Every action has an equal and opposite reaction.” I have a query about the word every in that sentence. Suppose we have two objects A and B. A pushes B with a force of 5N and B will push A with a ...
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### Friction-Newtonian Mechanics

Here we are having two blocks of mass $2~\rm kg$ and $4~\rm kg$ on an inclined angle with angle of inclination being $30~\circ.$ The block of mass 2 kg has a coefficient of friction $\mu_1=0.2$ and ...
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### How to solve this problem without using energy conservation

I believe most of you probably solved the following problem using energy conservation as shown here. It states a block of mass $m$ sliding on a sphere of radius $R$. I've be trying to solve this ...
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### Why is it exerted a torque from the wheel on the body?

I'm looking at papers about two wheeled balancing robots. But they all seem to have a torque acting from the wheel on the body. As seen in figure 7 bellow. $M_M$ is the torque in question. Even though ...
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### Friction-free rolling/sliding on an inclined plane

Suppose a sphere is rolling down an inclined plane. There is no friction. The body will not roll and undergo just a translation. But why is this so? If we consider the axis to be along the point of ...
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### Minimum force needed to keep the book from slipping?

I would just like to know if my answer to part C is correct because I am confident in parts a and b, Also note that 51.5N is the wrong value for P. P=515N. Ok so since P= normal force, this means ...
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### Is a normal force acting on an object that is hanging from the ceiling?

I've only taken two semesters of calculus-based physics as part of my general education credits at university. Please keep this in mind when reading this question and framing answers. Today I ...
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### Could we find the overall force and direction of something with a diagram only? (i.e. no calculation)

My friend, who is a geologist, and I were just debating some dynamics stuff. To make this easier, lets come up with an analogy......lets say there's a boat and it's being pulled by two smaller boats ...
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### Newton's Third Law

Sorry if this question's been asked. I looked through some of the questions but didn't find a similar enough question. My question on Newton's Third Law: It's my understanding that if you were in ...
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### The components of applied forces on the masses of a Trebuchet

Background information: I was following an online mechanics document in order to learn how to derive the equations of motion for a trebuchet (shown below) using Lagrangian mechanics. At some point ...
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### What is The force a body exerts on a vertical circular track?

I am trying to calculate the force a body exerts on a vertical circular track with no friction at its highest point I know the centripetal force at that point is mg and the given data is the velocity ...
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### Accelerations of Cylinders

I got a box hanging from a rope that passes through an ideal pulley that attaches to the superior part of a Cilynder and makes it rotate. An exercise asks me two things: a) determine the magnitude of ...
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### Non-uniform Normal force, friction

I got problems understanding the Non-uniform normal force. Why is it non-uniform? Because the object would have different densities in different parts, so weight would be greater in some parts? So ...
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### Astronauts on a tether

Recently, I went to a competition with a science test. One of the questions was as follows: Two astronauts (A and B) are tethered together in space. Simultaneously, Astronaut A pulls on the tether ...
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### Equations of Motion of a Physical Pendulum [closed]

I would like to formulate the equations of motion of a particular type of physical pendulum, shown in the attached figure. The physical pendulum consists of a wheel rolling on a narrow board. A ...
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### How do we define what is “External” force or “Internal” force in the context of momentum conservation?

I know that without presence of any "External" force momentum is always conserved. But how do we distinguish between "External" force and "Internal" force where all are "Force"?
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### Simple question about inclined planes

Assuming all surfaces to be frictionless. If the mass of the inclined plane is large enough, could $N$ ever be equal to $mgcos\theta$. Reasons? So far I've come up with: $mgcos\theta - N = ma$ ...
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### Newton's third law confusion [duplicate]

If A exerts a force of 200N on B, then by newton's third law, 200N would be exerted on it. Similarly, if B exerts 100N on A, by newton's third law, 100N would be exerted on it. Therefore the net ...
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### Centripetal force and friction

Here is the question I need help on: A hemispherical pile of snow with a height of 20 m is piled up. An extreme skier starts at the top of this snowball, and she skies down finding that ...
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### BASED ON NEWTON'S 3RD LAW [duplicate]

my question is based on newton's 3rd law . An elephant pushes a rabbit with $250 N$ force , then the rabbit should also apply $250 N$ force but the rabbit is only capable to apply $25 N$ force . Why ...
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### Is static friction the only force causing a car to move (without sliding)?

A car is moving without sliding means that the friction between wheels and the ground is static friction. This is the force causing an object to move forward, therefore, its direction is the same as ...
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### How do I use a free body diagram in this case? [closed]

In the above cases I want to find the acceleration $a$ for $m_1$. I can do it by considering $m_1$ and $m_2$ to be a system, which would give me $a = F/(m_1+m_2)$. How can I use a free-body diagram ...
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### Why is the centripetal force vector on a banked turn horizontal rather than parallel to the incline?

Why isn't the centripetal force parallel to the inclined surface? It seems like if you were to draw a circle with one point being at the center of the curve and one point at the car the circle would ...
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### How can gravity have a horizontal component?

$mg$ obviously has no horizontal component, but on resolving it into components it seems to have a horizontal component $mgcos\theta sin\theta$. I know I'm doing something wrong here. How is this ...
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### Action is equal to reaction. Then how is a horse able to pull a cart? [duplicate]

Please answer the question in detail. I have tried other websites for answers but was not able to understand properly.
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### I need help with determining angles after shifting of axis in Free Body Diagrams

I can't figure out by which property of the triangle the angles in shifted axis are also 30 degrees. Vertical angle theorom doesn't work. I drew it again and again. If someone could draw me a diagram, ...
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### Force conversion in a barrel cam-follower mechanism

A barrel cam-follower mechanism consists of a (cylindrical) barrel with a cam track, a cam-follower (roller) inside of the track, a fork connected to the cam-follower and a guide along which the fork ...
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### Problems with work on an inclined plane

A constant force $F_a$ of magnitude $82.0N$ is applied to a $3.00 kg$ shoe box at angle $53.0^{\circ}$, causing the box to move up a frictionless ramp at constant speed. How much work is done on the ...
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### Question about aircraft/rockets

Lets say that you're sitting an inverted airplane. How do you determine how fast the plane must accelerate in order for you to not fall out?
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### Why does the water in a bucket stay even when swung around in circular motion? [duplicate]

What are the force that act on the water and which force is responsible to keep the water from falling out?
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### Stuck on a static equilibrium problem [closed]

This is the problem: "The figure below shows a 25-foot sailboat. The mast is a uniform 119-kg pole that is supported on the deck and held fore and aft by wires as shown. The tension in the forestay ...
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### What component of the payload appears on the cross member? [closed]

I have a set of DIY steps; I've modelled it as the steps themselves "s", a short vertical support "a", a long vertical support "b" and a cross-member "c". Here's a picture: Just to be sure I ...
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### Draw the Free Body Diagram

Question: Draw the Reaction Force at point P. My Attempt and Reasoning: Since the Reaction or the Normal Force is normal to the surface the solution according to me should be- However, the ...
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### Normal force on vertical circular motion

I have a couple of questions concerning vertical circular motion. The object shown in the diagram moves with constant speed on the inside of a circle. In point A the normal force points to the center ...
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