Newtonian mechanics covers the discussion of the movement of classical bodies under the influence of forces by making use of Newton’s three laws. For more general discussion of energy, momentum conservation etc., use classical-mechanics, for Newton’s description of gravity, use newtonian-gravity.

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Conservation of angular momentum in a free rod

When a collision is elastic and no external torque acts on a system, angular momentum is conserved I found this example and checked the results: A ball (m = 1 Kg , v = p =+22 m/s, Lm = +11, Ke = 242 ...
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298 views

How does the space shuttle move in a vacuum? [duplicate]

If there is no friction in space, then how does the space shuttle boost? According to Newton's law we move by pushing something; in space, there is vacuum, so how the space shuttle moves without ...
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337 views

Why does $k/m=\omega^2$ for harmonic motion? [closed]

Can anyone please give me a proof for $k/m=w^2$ in simple harmonic motion? I have tried energy conservation and Newton's laws as follows : In the case of a mass-spring system, $$F=ma =-kx\\ F=ma = ...
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2k views

When is tension constant in a rope?

Suppose we have a massless rope with pulling forces applied at each end. In which scenarios is the tension in the rope constant throughout? For example if there is a knot in the rope the tension is ...
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83 views

Running Euler's disk in a superfluid

I was considering the toy Euler's Disk, a video can be found here: http://www.youtube.com/watch?v=mVl2CBG_h2s I was interested in understanding the behavior of the disk particularly in vacuum and in ...
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309 views

Force of a Train

Imagine that there are two trains and the first train is twice as long as the second train. They have the same mass per unit length and they are traveling at exactly the same speed. If the first ...
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157 views

How do you find the tension in the real world? (Given a rope in a pulley system)

I'm well aware of the formula to calculate tension, however, given a real world situation where you have a closed pulley system. How do you measure the force (i.e., tension) required to pull on the ...
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99 views

Why do these two derivations of the formula for impulse contradict?

I was trying to derive $I = F\Delta T$ from $p = mv$. First I converted $v = at$: $$\begin{align} p &= mv \\ p &= m \times at \\ p &= ma \times t \\ p &= Ft \\ \Delta p &= F ...
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102 views

Disk and Ball on a smooth surface [closed]

A uniform disk of mass $\text{2m}$ and radius $\text{R}$ is placed freely on a smooth surface as shown in the figure. A particle of mass $\text{m}$ is connected to the circumference of the disc with a ...
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149 views

What really is “inertial force”?

In Fluid Mechanics we often see the term inertial force when discussing Reynolds number. The problem is, I didn't really get what's this inertial force. Basically, the notion of inertia I have is that ...
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126 views

Projectile motion where gravity is a function of $y$

I know what are the laws that describe the projectile motion, and in particular I need to compute the vertical displacement of the projectile at any time $t$: $$ y = y_0 + v_0\sin(\theta)\,t - ...
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147 views

Can a body ever experience acceleration this strong?

Using the Schwarzschild radius formula, I approximated the Sun's Schwarzschild radius to be $3\text{ km}$. Now assuming I have a body (not a human body) which is at a distance of $10\text{ km}$ from ...
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667 views

Is there a normal force on an object submerged in water?

I am not sure about whether or not there is a normal force acting on an object submerged in water. It might be because I have not good understanding about what a normal force actually is. I know a ...
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1answer
108 views

What is the point of this type of graph? (Projectile) [closed]

What is the point of graphing vs range, during kinematic motion?
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109 views

force acting perpendicular through a rotational axis

This seems rather basic to prove mathematically but i am second guess my intuition. Say you have an object in rotation and a force acts on it through the axis of rotation perpendicular to the axis of ...
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130 views

Newtonian tidal forces and curvature

Today in my physics class, my lecturer said something which confused me. He said: "Newtonian tidal forces are reinterpreted as a manifestation of curvature in General Relativity". Now I know what ...
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59 views

Projectile motion. Is there a point where sum of the forces is 0?

Body of mass m, is thrown with initial speed, at an angle α from a horizon. Neglecting wind resistance, is there a point on the trajectory where the sum of forces is 0? I don't think so, but maybe at ...
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83 views

Does a ball spin more from left to right than it does from right to left?

I swear that in a manual on tennis published by the German Tennis Association (Deutscher Tennis Bund) it stated as fact that all things being equal a ball will move more from left to right than from ...
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460 views

Is a double integral required to find the moment of Inertia of a non-uniform sphere?

Consider some ball of given radius $R$, with a mass density function that depends on the radial variable, $\rho=\rho(r)$ where $r$ is the distance from the center of the sphere. What is the moment ...
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58 views

Which inertial observer should I choose when using $\Delta U = -\Delta K$?

I just read and undertood that For any conservative force $F$ (which is not necessarily constant), we can define a potential energy change $\Delta U$ of an object on which the force exerts as ...
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154 views

Moment of inertia help [closed]

Okay so lets say I have a lever with 2 objects on it, object one and object 2. Object 1 has a mass of $m_1$ and is $r_1$ away from the fulcrum; object 2 has a mass of $m_2$ and is $r_2$ away from the ...
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83 views

Line integral calculates work, even though the force from the vector field doesn't cause the movement?

I'm afraid the title here was unclear, so I'll attempt to make things a bit more clear. I am conceptually confused about the physical meaning of line integrals over a vector field, so I'll pick an ...
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9k views

If mass is added to a toy car does it affect its speed making it faster

If mass is added to a toy car (29.7g) and dropped down a wooden ramp would it affect its speed making it go faster? I know friction comes in to play to, so if you could give me an answer or an ...
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173 views

Solving equation of motion with exponential friction term

My friend's kid asked me this question. I have no idea how to solve it since I have stopped calculating mechanics for about 15 years since I graduated from high school. The question is: A boat that ...
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185 views

Electromagnet force equation clarification

So, from a previous previous question, I know what plane the force from an electromagnet will affect a ferromagnetic material in. I thought that would be enough, but working through some problems ...
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755 views

Why does the work done by an internal force differ from the work done by external force?

Let's consider the following situation. We put a body of mass $m$ at a distance $A$ from the center of Earth. We let the Earth attract the body and analyze the situation at a point $B$, closer to the ...
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298 views

Work done by gravity on a ball & the ball on earth

I have studied today that if a ball was to fall a certain height, then the work done by gravity on the ball would equal the work done by the ball's equal and opposite gravitational pull. By $W=Fd$, ...
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171 views

An oscillating skateboard

A half pipe of a skateboard park consists of a concrete trough with a semicircular section of radius 5m, I hold a frictionless skateboard on the side of the trough, pointing down toward the bottom and ...
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493 views

Inertial frames

I'm just starting my study of relativity, and I have a rough understanding of the connection between inertial frames, newton's laws, and galilean transformations, but I'd probably benefit more if ...
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961 views

Force Diagram for K&K 2.13 [closed]

I have been (independently) working on Problem 2.13 in Kleppner and Kolenkow's An Introduction to Mechanics and come to an answer which conflicts with the hint the authors provided in the book. The ...
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73 views

Action Reaction Pairs and Work

Say that a ball is sitting in front of a compressed spring launcher. The spring is then released. The spring applies a force on the ball for a certain distance. This force is accompanied by an equal ...
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563 views

Massive ropes and tension

Consider the diagram bellow, a massive string hanging in equilibrium My question is this: Can we take any 2 random point on the rope, say A and B and then use $\sum F=0$ on the rope between them: ...
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93 views

Hooke's Law: why is only one force considered?

I have a question about Hooke's Law springs. What I learned is that a Hooke's Law spring gives a force F pushing left and right and each force equals $k \cdot |l-l_o|$ Let's say there is a mass ...
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304 views

Will A Vertical Projectile Travel the Same Distance as A Horizontal Projectile

If a projectile is fired vertically from an initial height, $h$, above ground level, and an identical projectile is fired with equal initial velocity from the same initial height in the horizontal ...
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528 views

Free vs bound vectors and torque

When considering basic Newtonian mechanics, we can treat vector as free and move their point of application at will. This is consistent with the affine nature of Euclidean space. However, when ...
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520 views

Coupled Spring System (3 mass 3 springs)

Hello I am having trouble trying to find the correct model for this coupled spring system. The scenario is the following we have: Ceiling - Spring - Mass(1) - Spring(2) - Mass(2) - Spring (3) - ...
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233 views

What indicates if an object will bounce back?

If I throw a small rock (m = 1kg) at a big rock (100kg) the small rock rebounds. Let's say my weight is 80kg, if I would jump into a big rock instead of bouncing back I would move in the same ...
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197 views

What force counteracts friction when a block is pulled?

Firstly, I understand and apologize that this is more of a physics question than a math question. I noticed that when I pulled a book out from under a pack of gum, the gum stayed largely in place (it ...
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2k views

Torque due to Gravity

I have learned that a torque on an object due to the gravity can be calculated as if the gravity acts on the center of mass of the object when the object is near the surface of the earth. Now I want ...
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51 views

If a planetoid was wet and you spun it would the water move to the equator?

If the moon was alone in space and covered in X feet of water and it began to rotate would it displace to a bias along the equator?
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90 views

What force does a tall building exert on air?

I once heard that a tall building, let's say 10 stories, actually causes wind to blow by virtue of simply existing. It also was said that is why metropolitan downtown areas tend to be windy. What are ...
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420 views

Constraint and Applied forces

In D'Alembert principle forces are classified into constraint and applied forces ? Is this classification different from internal-external forces ?
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Follow up question regarding: Deceleration rate of objects of different mass but the same otherwise

My first question was answered here: Deceleration rate of objects of different mass but the same otherwise . But based on that, here is a follow-up question (I also edited my first post with the ...
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1answer
53 views

Inertial navigation system: am I doing it wrong?

I'm trying to develop an inertial navigation system. I can access data from an accelerometer sensor (acceleration on three axes) and gyroscope sensor (angular velocity on three axes). First of all, ...
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190 views

Do lawn mowers still cut the grasses if they aren't attached to the ground?

A rotary lawn mower cuts the grasses by rotating it's sharp blade on it but if the grasses aren't attached to the ground will they still cut them? What forces act on this system? I know the answer is ...
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41 views

Clarification what exactly this question wants regarding force [closed]

I would like to ask you if the question asked What is the minimum force parallel to the plane, which can be prevent the block from slipping down the plane? I just did the calculation and and ...
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50 views

Forces acting on particles

What is the difference between air resistance/friction force and up thrust force? I always think that air friction is the same as up thrust but it does not seem that way.
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Deriving Bernoulli's equation via conservation of E

So I'm not OK with how some people derive this equation. These people consider a pipe whose endings have cross-sectional areas and heights which are different. They then use the conservation of ...
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193 views

What are some good resources for learning how to apply vectors in physics?

Although I don't have any problems with vectors when using them in Mathematics but I am having a hard time using them in physics. It is really frustrating me. Can you please recommend me some good ...
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91 views

If and how are the Coriolis force and gravitation related?

I recently got into a discussion whether and how the Coriolis force/effect is related to gravitation. Is gravitation involved in the Coriolis force? If so, how could that be explained?