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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Does Newton's 3rd Law apply to friction?

Supposed body A slides on a surface. The will be a kinetic friction that acts on body A and opposite its relative motion. However, is there a kinetic friction that acts on the surface too i.e. the ...
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31 views

Modelling an Inelastic Collision

I've attempted to model the inelastic collision between a moving mass and a large stationary object, e.g. dropping an ball on the floor, for analysing the approximate kinematics and heat dissipation ...
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33 views

Plasticine experiment [on hold]

I am doing an experiment in my high school, with plasticine (I did not choose it, it was stupidly given to us). So my idea is to see how the diameter of a plasticine ball (flat bit) varies with the ...
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2answers
61 views

Thought Experiment: An object falling indefinitely under gravity?

So the other day, I devised this thought experiment: Consider an infinite tunnel, and you drop a coin of mass $m$ into it. Considering the effect of gravity to be applicable and neglecting air ...
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34 views

Does a projectile always meet a freely falling body when aimed at it? [on hold]

When we aim a projectile at a freely falling body why does it always meet it irrespective of the range and speed.
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What happens to KE when lowering a raised book?

I understand the conservation of energy theorem and mechanical energy, but there is this question that confused me a bit, so I hope someone explains it. If you had a book and you raised it, you gave ...
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Could you please help me find another example of motion under null net force? [on hold]

There are many familiar situations in which the net force on a body is zero and yet the body moves with a constant velocity. Here is one example: A car traveling at constant speed on a ...
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17 views

Lorentz force solving and integration [on hold]

I have a question on how to get gyro frequency from lorentz equation. The question is attached below. I have also attached what I have done so far, but looks wrong. How is this question done; a) ...
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23 views

Calculating the torque required to move a heavy object (the calculations)

I wanna choose a motor for my bicycle and turn it into an electric one. So the physics part shoots. The force (Force=Mass x acceleration) that i will exert on earth surface(weight) will be my ...
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3answers
67 views

Kinetic energy of the object, but Potential energy of the system: Why is it so?

Examples from Principles of Physics (by Walker,Resnick,Halliday) will say it better: Let us throw a tomato upward. . .as the tomato rises, the work $\mathbf{W_g}$ done on the tomato by the ...
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2answers
35 views

What factors influence the spring constant?

For certain springs we have been taught that Hookes law, $F=-kx$ works. For such springs, what factors determine k. For instance, k is proportional to length. Can k be expressed in terms of ...
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3answers
73 views

A problem related to Work done by falling bodies : Expert's attention much needed! [on hold]

I'm having a lot of trouble with this question, that I've found in my textbook. I've solved it in my own way and it's very simple! But the solution in the book is totally different. It doesn't make ...
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29 views

Deceleration of a space shuttle [on hold]

A space shuttle is decelerated by parachutes, which cause a deceleration of $a(v)=-0.04 v^2$. After what time is a space shuttle decelerated to $1m/s$ if it had a velocity of $50m/s$ when the ...
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2answers
43 views

Confusion with potential in simple pendulum

I'm a maths student taking a course in classical mechanics and I'm having some confusion with the definition of a potential. If we consider a simple pendulum then the forces acting on the end are ...
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0answers
25 views

Velocity of ball after collision [on hold]

I have a question regarding impulse. Suppose at a certain point of time ball has velocity $\mathbf{v}\cos\theta$ in horizontal direction and $\mathbf{v}\sin\theta$ in vertical direction (downwards) ...
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6answers
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Throwing an object around the Earth. Is it possible?

Some of you might be familiar with the cartoon called Astérix. In one of the episodes, Obelix (the really strong fat guy in the stylish striped pants) enters a spear throwing competition. He beats the ...
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2answers
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Traveling to Mars in 24 Days

I am trying to calculate an electromagnetic rail launch from the Moon but I need to know if humans can survive the launch. Please see the specs below. 150 miles of track Proposed final launch speed ...
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0answers
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Men on the pully palte to lift [on hold]

A plate has a fixed pulley. A men, standing on a plate pulls up with one end of the rope to try to lift the plate and himself; the other end of the rope is over the pulley to fixed on the ceiling, ...
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0answers
28 views

classical-mechanics [on hold]

If the mass of person is less than the mass of elevator, the $\mathit{N}$ will be negative. What does that mean? For instance: person mass = $30~\text{kg}$, elevator mass = $60~\text{kg}$. At ...
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1answer
26 views

A question on tangential and centripetal accelerations?

What is the proof that the component of acceleration perpendicular to motion for all motion is $v^2/r$, where r is the radius of curvature? Also, what is the proof that the component of acceleration ...
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1answer
16 views

Problem on bending plates in Newtonian Mechanics?

I am reading a book on interesting physics problems and demonstrations. One of the problems in the section on buildings, structures and equilibrium talks about a plate with one side attached to the ...
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1answer
17 views

Is the buoyant force on an object is the reaction force?

Is the buoyant force on an object is the reaction force for the force exerted by the objects on the fluid (newtons third law)? Or there are two sets of action reaction force? (objects force and ...
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1answer
47 views

Lagrangian mechanics and initial conditions vs boundary conditions

It bothers me that many basic books on the classical mechanics don't discuss the following difference between "Newton's laws" and the "Principle of stationary action". Newton's laws can predict the ...
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30 views

Equation for Figuring out the Displacement for a Projectile at an Angle

I'm wondering if anybody can simply tell me if there is a simple formula to solve for displacement when you've been given the launch angle and initial velocity? See; http://is.gd/LpT1EA To some, it ...
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1answer
21 views

Balancing sphere

A cube is balanced on the very top of a sphere, and is given a small push in some direction, at which point it begins sliding down that side of the cube (due to gravity). Now, I want to keep the cube ...
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0answers
10 views

dynamics: force, pulley, person in elevator [duplicate]

An 30-kg person standing on a 60-kg elevator suspended by a rope passing over a stationary pulley that is free to rotate. The other end of the rope is held by the person. The masses of the rope and ...
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27 views

In relation to what, are the orbits of planets defined? [on hold]

I was pondering geocentric orbits. And of course, a geo-stationary orbit is an orbit in which a satellite orbits at the same speed and direction as the rotation of the Earth, so that it seems from ...
4
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1answer
55 views

Uniqueness of the equivalence class of inertial frames

Let us define an inertial frame as a frame of reference where the laws of physics take their usual form, as opposed to non intertial frames where one has to introduce pseudo-forces. We can further ...
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30 views

Two cars colliding with different speeds

If I have one car travelling at 30 m/s and another travelling at 10 m/s both weighing the same amount, why is it that the car travelling 10 m/s would have more damage? According to Newton's third law ...
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1answer
15 views

Circular motion normal force

Extracted from this article (see the bottom section): Some roller-coasters have loop-the-loop sections, where you travel in a vertical circle, so that you're upside-down at the top. To do this ...
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4answers
68 views

Absolute (as opposed to relative) concept of inertial frame

In mechanics there is a relative concept of "inertial frame": frame A is inertial with respect to frame B if A moves uniformly with respect B. That concept is easy to understand. There also seems to ...
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34 views

Under what circumstances will a particle in a paraboloid oscillate harmonically around the lowest point? [on hold]

A particle of mass $m$ is moving in the gravitational field $g$. It is confined to move frictionlessly on the surface of the paraboloid $z(r,\phi):=a\cdot r^2$. Here, $a>0$ is a constant. The ...
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1answer
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will frictional force work against the vertical direction of velocity of an object?

We assume that an object is placed on a horizontal plane. If this object is accelerated to vertical direction, will frictional force act against the vertical direction of velocity of object? For any ...
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3answers
60 views

Is the work-energy theorem valid for only particles or rigid bodies as well?

Is the work-energy theorem valid for only particles or rigid bodies as well? Most places where I have read this seem to claim the latter. But an example I thought up has been troubling me. Consider ...
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If the solar system is a non-inertial frame, why can Newton's Laws predict motion?

Since there is no object in the universe that doesn't move, and the solar system likely accelerates through space, how did Newton's Laws work so well? Didn't he assume that the sun is the ...
2
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1answer
194 views

Is force the derivative of energy?

In my lecture today my professor briefly mentioned that force is the derivative of energy but I did not really get what he meant by that. I tried to express it mathematically: ...
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1answer
16 views

Pure Rolling from a stationary surface onto a moving surface

Suppose a sphere rolls without slipping on horizontal stationary ground. Now, suppose the sphere rolls onto a surface which is moving at some velocity with respect to the previous stationary ground. ...
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What is the use of orthogonal curvilinear co-ordinate system?

Orthogonal curvilinear coordinate system is made of intersecting sets of confocal ellipses & hyperbolas. But, I have found no book that would describe this how to use this coordinate system ...
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30 views

Vector Physics Line Point Collision [on hold]

Question: What laws should I use to distribute the net velocity where: A Ball collides with a rope that always stays at high tension with two Balls on both sides which have arbitrary velocities. ...
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2answers
35 views

Can center of mass move without any force?

For instance, consider a weight on one end of the ring. Assume that the ring has negligible mass compared to the weight. When the weight splits into two, moves around the ring and recombines at the ...
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2answers
63 views

An interesting problem on springs [on hold]

If I place two identical objects of mass $m$ at either end of a spring with spring constant $k$ and the whole system is placed on a horizontal frictionless surface, then what is the frequency of ...
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1answer
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Very confused about effective spring constant

I know that for springs in parallel, the effective spring constant is $k_1+k_2$ and for springs in series the constant is $1/(1/k_1+1/k_2)$. But there are some weird problems where finding the ...
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1answer
36 views

Tipping over objects on a frictionless surface

Is there any way you can topple over a rod which is standing up on a frictionless surface?
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1answer
50 views

Where does energy goes if I jump down from a balloon?

Suppose you are in a hot air balloon of mass $M$ which is floating in the air, and you get out and start climbing down a rope at constant velocity $v$. By conservation of momentum we can show that the ...
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2answers
37 views

Linear Gravity Inside Solid Sphere Derivation

I am currently taking a dynamics module at university and am revising for a midterm exam. One of the problems on a past paper was to consider a mass falling through a hole in the Earth (pole to ...
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3answers
58 views

How to explain that an object at a certain point with zero velocity can move away from that point by having an acceleration?

As A.P.French points out: You may feel, . . . , that we have gone to excessive lengths in our discussion of instantaneous velocity & acceleration. But make no mistake about it; these are very ...
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Clearing up confusion about orbital mechanics

When I see an orbital mechanics problem, I recall the following things from my "toolbox": Angular momentum is conserved for a body orbiting a planet, since the torque due to gravity is 0. Kinetic ...
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1answer
53 views

Springs at an angle [closed]

I'm trying to find the equation of motion for the following system: This is how I proceeded: Let's call the length of the hypotenuse $s$. Then, $$F = 2 \sin{\theta}\cdot-k(s - l_o) = -2kx ...
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1answer
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If a place a spring in a box and drop the box, what happens?

Suppose I a holding a box in my hands, and inside the box a spring with some mass attached hangs from the cieling of the box. Initial the system is at equilibrium, then I let go of the box and it ...
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1answer
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Placing an object in a tub changes the weight of the tub?

Suppose you have a tub filled with water and it rests on a scale so you can measure the weight. If you place an object in the tub, will the reading on the scale change? Clearly if the object sinks ...