# Questions tagged [newtonian-mechanics]

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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### Block on an inclined plane. 1 solution or 3? [closed]

I have done all of the work to this problem, but I am having trouble conceptualizing the answer(s) I am arriving at. A block is placed on an inclined plane at an angle of $30^\circ$ to the ...
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### Tension in Ideal Strings

I know that elastic strings have zero tension $T$, when it has it's natural length $L$, and that they experience tension when there is some elongation. In the case of ideal strings, which are ...
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### Different approaches gives different results: planetary gear problem?

I am having a homework: "A planetary gear system with a fixed gear 1 (radius r1); gear 2 (radius r2) is movable". At begining, the system is stationary. Apply a constant torque M to OA bar. OA bar ...
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### Does an initial condition of “at rest” mean that the velocity is zero, but the acceleration could be nonzero?

I'm solving a differential equation for the relativistic motion of an electron in an electric field. The electron is initially at rest in the uniform field, but I am not sure if the initial condition ...
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### G-force: difference between gravity and acceleration of an object

I'm trying to simulate the perception of weight by a human in a system but I'm struggling to treat gravitational acceleration and other accelerations in the same way. As I understand, when I stand on ...
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### Is it possible for a motion to be isochronous (time period is independent of amplitude) but not true s.h.m.? Can an s.h.m. be non-isochronous?

Is it possible for a motion to be isochronous (time period is independent of amplitude) but not true s.h.m.? Can an s.h.m. be non-isochronous? Another question I have is do all periodic motions ...
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### How to determine which car/truck will pull given their acceleration, top speed etc?

So let's say if two cars were having a tug of war, pulling each other. and we know all about the cars their top speed, acceleration, towing capacity and all. how can we determine which car will pull ...
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### Wave equation as a consequence of Newton's second law

How the linear wave equation is a direct consequence of Newton's second law applied to any element of a string carrying a travelling wave?
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### Can the forces change with frame of reference?

Consider a ball kept on man's head (mass $M$) on the Earth. Now supposing I throw the ball from height $h$ of tall building then why does he gets more hurt? Isn't the force still mg? I would like to ...
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### The Feynman Lectures

Page 4-5 of The Feynman Lectures, under the topic of conversation of energy, writes this, while it tries to give a feel about conservation principle. Let us now illustrate the energy principle ...
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### Does an action-reaction pair always contain the same kind of force?

According to Newton's third law, the forces in an action-reaction pair must have the same magnitude and opposite directions. But do they have to be the same kind of force (gravitational, ...
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### Work Done by a time-variable Force

My problem gives a time-dependent force as follows: lets say that the force is fairly simple, $F=6t$ lets say that we want to find the work done in the 1st second. Here's my approach: $W=F(t).v$ ...
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### Finding the height of the slope of a rollercoster loop-de-loop with friction [closed]

I have the following diagram: I am given all the listed parameters in the diagram, plus the mass of the pink body. The red track has a friction coefficient with the body equal to $\mu$, and the loop-...
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### Clarify definite integration of differentials in physics problems

I realized there is an issue with integration in physics problems that I had always taken for granted. As an example, the relation between work and potential energy is $dW=-dU_p$ when integrating ...
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### Frictional force doesn't depend on surface area, but why does this application work?

I know friction doesn't depend on surface area and the professor has been demonstrating the same in all the previous lectures. But in this lecture he shows an application where the friction helps in ...
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### Why do tires move forward?

I have heard a lot of people saying that when the tires of a car rotates backward, a friction acts in forward direction on the tire and the car moves forward. Now according to my physics book, " ...
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### How hitch placement affects the turning radius of bicycle/motorcycle + trailer assemblies

Many bicycle/motorcycle cargo trailers contain some form of pivot. However, there are multiple kinds of trailers that attach at different places. Some attach to the rear axle, and pivot after the rear ...
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### Do automobiles leave less tracks when driving fast?

A truck drives through the desert (or some other material where it can leave tracks), would its tracks be more shallow if it's driving fast?
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### Tension in an ideal string

An ideal string is massless and frictionless. The tension at every point is same. If some tension is developed in the string, then a common tension , say $T$ is present at every part of string. That ...
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### Does a force does more work on an extended body?

$$\underline{\pmb {Assumption}}$$ Assume a place free from any gravitational or other kind of influences (like friction, drag, etc.). Now assume a thin cylindrical rod of mass $M$ and length $l$. ...
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### Rigid bodies in non-inertial frames [closed]

I know fictitious forces arise when you are performing observations in a non-inertial frame. However, the calculation of the effects of these forces is easy only in the case of a point mass analysis....
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### Ballistic acceleration in low $g$

A simpler question please: What is expected if a bullet were to be shot straight up on the Moon or Mars, vs. what the same caliber bullet shot with the same trajectory on earth? I'm distinguishing ...
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### FBD with a system with glue

I am trying to understand how Adhesives or glues work. In the process I started thinking of drawing the Free body diagram. What will the FBD look like for the Blocks A, B and the adhesive itself? (I ...
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### Automatically embedded in Lagrangian formulation

Since bond forces are automatically embedded in Lagrangian formulation, while in Newton they are not, and you have to operate directly with them [you have freedom from generalized coordinates]. That's ...
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### Which collision equation is appropriate to use?

Take this example problem: A 2 kg ball moving east at 3 m/s that enters in collision with another 1 kg ball moving west at 2 m/s. After the collision, the 2 kg ball has an eastward speed of 10 m/s. ...
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### Alternative Interpretation of Angular Simple Harmonic Motion

A Linear Simple Harmonic Motion can be interpreted as the projection of a uniform circular motion on a diameter of a circle, as depicted in the following image. Image Source: Simple Harmonic Motion (...
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### Newton's First Law and Objects in momentary rest

When an object is projected vertically up, its velocity at the highest point will be zero. But the net force is not zero, and is $mg$ vertically down where $m$ is the mass of the object and $g$ is the ...
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### Is it really necessary for the orbital plane of a satellite to pass through the center of mass of the object around which it's orbiting?

Is it really necessary for the orbital plane of a satellite to pass through the center of mass of the celestial body around which it's orbiting? Does the answer depend on, whether the celestial body ...
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### Deflection of a Falling Mass at pole

I know that falling objects on the earth are deflected horizontally. But could anyone tell me how can we calculate the deflection of a mass m dropped from a tower of height h at the north pole?
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### Person sitting on rotating stool, holding a wheel, and conservation of angular momentum

Let us say we have this configuration A person sitting on a rotating stool, which is initially at rest, holding a wheel that is rotating as indicated in the figure. The person then changes the axis ...
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### Will a falling rod stay in contact with the frictionless floor?

Question A uniform rod of mass $M$ is placed almost vertically on a frictionless floor. Since it is not perfectly vertical, it will begin to fall down when released from rest. I have seen ...
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### Relationship between thrust of thrust of back and front rotors to achieve angle of pitch in quadrotor dynamics model?

So I'm learning the physics of quadrotors and have come across a question. The dynamics of how multi rotor machines fly is simple in theory, but much physics in practice. Have 4 rotors. 2 spin ...
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### Would a buoyant force still act if the object is placed at the bottom the fluid(without any gap for the fluid to enter)? [duplicate]

When an object displaces a fluid a force acts on the object which is equal to the mass of the fluid displaced by it (for the logic see here ). But the fact that a net (buoyant) force acts on it is due ...
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### An absurdly complicated, simple force problem

In my high school physics class, we're learning about analyzing force diagrams, with quite simple problems about blocks sliding down ramps. One of my friends decided to parody the hilarious "realism" ...
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### Is tension along the length of a massive rope resting on a table always the same?

Mathematically it can be easily proved using Newton’s 2nd law that tension along the length of a massive rope just lying on a table and not accelerating, is the same. But is it always the same? It ...
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### How much do the Newton's laws of motion affect the equilibrium statistical mechanics?

Equilibrium statistical mechanics deals much with possible configurations of a system than the governing laws of dynamics (Newton's laws in classical statistical mechanics). My question is: to what ...
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### Would the moon eventually hit the Earth?

The moon is rotating around the earth in elliptic or approximately circular orbit with speed $v$. Its acceleration have two components tangential and radial one. It is the radial acceleration ...
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### Why are planet's maximal/minimal angular speed ratio harmonic?

See this Wikipedia page for Harmonices Mundi, a book by Kepler (yes, he was the one to discover the three Kepler's laws). The author writes: He found that the difference between the maximum and ...
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### What if we take jerk (i.e. the rate of change of acceleration) in Mechanics? [duplicate]

Actually in Mechanics rate of change of acceleration with time is not considered.Why is it so?Is the rate of change of acceleration with time not important? Or there exist any cases, where we can ...
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### Confusions about frames of reference when deriving Euler's equation of rotational motion

I am getting confused about when torques should be frame independent. My understanding is that torque is the same in all frames that are rotating at constant angular velocity. However, this seems to ...
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### Actual velocity of an non-accelerating object in Newtonian physics

How was the velocity of an non-accelerating object (i.e moving at a constant velocity) in empty space, determined in Newtonian physics? Did Newton also considered it to be at rest, if not how is its ...
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### If Earth accelerates, what reference frame is its acceleration relative to?

It should be a very fundamental thing, a very simple question. But there's something I want to understand. We know that when we throw an apple vertically upwards, it experiences a force of gravity ...
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### Stress tensor and second invariant

While calculating yield stress in case of Von Mises and Tresca and proving that Von Mises in 15% above Tresca they assumed uniaixial loading while applying distortion energy theorem and pure shear in ...
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### Are the models describing the classical gravitational and electric fields mathematically equivalent?

In other words if I have a static point mass and a static point charge, we model them as having a scalar potential field surrounding them: $$V(r)\propto\frac{1}{r}$$ and their vector fields are ...
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### How do you find the initial velocity and angle required to hit a coordinate and a certain height?

Problem For a game engine I'm writing, I need a function that returns the initial velocity and angle of a projectile launch, such that the affected object reaches a given maximum height, and ends up ...
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