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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82 views

Friction to just move the blocks

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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0answers
30 views

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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1answer
21 views

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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2answers
134 views

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 ...
0
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2answers
48 views

Accelerated frames conceptual doubt [on hold]

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 ...
0
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1answer
28 views

Newtonian mechanics, block on conveyor belt [on hold]

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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1answer
40 views

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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3answers
63 views

What is acceleration of A and how to approach such accelerating pulley problem [closed]

As shown in figure A and B are free to move pulley and rope are mass less, there is no friction at all between any two. Now my question is because of tension in rope, A will move left but how will B ...
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6answers
3k views

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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4answers
75 views

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 ...
6
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4answers
279 views

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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1answer
49 views

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 ...
3
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3answers
73 views

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 ...
0
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2answers
50 views

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 ...
3
votes
4answers
90 views

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 ...
0
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1answer
31 views

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 ...
0
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2answers
53 views

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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1answer
36 views

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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1answer
34 views

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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1answer
42 views

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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1answer
37 views

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 ...
7
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5answers
136 views

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 ...
6
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2answers
129 views

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 ...
1
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2answers
80 views

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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2answers
47 views

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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0answers
40 views

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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2answers
36 views

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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0answers
28 views

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 ...
3
votes
3answers
117 views

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 ...
0
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2answers
52 views

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 ...
2
votes
2answers
61 views

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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votes
2answers
81 views

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 ...
0
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4answers
87 views

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.
0
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1answer
26 views

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, ...
0
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0answers
42 views

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 ...
0
votes
2answers
65 views

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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2answers
49 views

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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1answer
36 views

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?
1
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1answer
33 views

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 ...
1
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1answer
44 views

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 ...
1
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4answers
102 views

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 ...
2
votes
4answers
306 views

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 ...
1
vote
3answers
106 views

How to explain the force applied on this object? [closed]

Sorry for posting such a simple problem but I'm having trouble understanding this concept. In the picture below, we have a force, $ \vec F_{app}$ acting on two objects, A and B. Mass of block A: $ ...
4
votes
4answers
1k views

What Keeps a Pendulum Moving In a Circular Path?

From the figure, we know that $F_{net} = mg\sin\theta$. Now, this force $\vec{F_{net}}$ is in the direction of the velocity $\vec{v}$ of the bob, both are tangent to the path. Therefore, the net ...
0
votes
4answers
87 views

What is the Role of gravity?

I am new to physics and I understand gravity is a pulling force. Let's assume a ball has been placed on the ground. Does gravity has any role after I placed an object (e.g. ball) on ground? Sorry,...
2
votes
1answer
65 views

$P = h \rho g$ derivation

Here is a snapshot from my textbook : Here only three forces are calculated: The gravitational force The force due to the pressure $p$ on the bottom surface The force due to the pressure $p+\...
1
vote
2answers
270 views

Why does something on an inclined plane move forward at all?

We just started studying about the inclined plane and vectors in motion, but i don't understand one thing: Why on earth does the object on the inclined plane move forward (I.e in the direction where ...
0
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1answer
58 views

How does paddling in the water help a boat move forward?

The way I've seen it explained is like this: it all has to do with Newton's third law. However, the "equal and opposite" reaction predicted by the third law acts on the paddle - which is not ...
1
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1answer
40 views

Dependence of tension (considering a pulley system) on the mass of loads

Consider the diagram below All circles are pulleys, which are fixed at the ceiling. M represents an engine (with a certain power) that is pulling the cable. C and D are weights. The acceleration of ...
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1answer
88 views

Sliding blocks problem

My first post here, so I apologize if this is duplicated elsewhere. It IS a "homework" problem, but it's public domain, a posted exam with answers... http://www.mun.ca/physics/undergraduates/...