# Tagged Questions

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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### Total Linear Momentum Conserved for Earth-Sun System? [closed]

According to 'Introductory Astronomy and Astrophysics' by Smith and Jacobs the total linear momentum of an isolated system is constant which they choose as zero, so they get (mv)1 = (mv)2. When I ...
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### About a particle suspended by a string, moving around in a circle

The question I'm trying to answer is this: I'm having difficulty with understanding this part of the soloution: I understand how a formula for $v$, the velocity of the particle, was derived, but ...
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### in motion , The moving object is either a particle (by which we mean a point-like object [closed]

in motion , The moving object is either a particle (by which we mean a point-like object such as an electron) or an object that moves like a particle (such that every portion moves in the same ...
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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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### Why don't hexapods gallop?

I haven't observed any terrestrial hexapods that gallop like agile tetrapods(cheetahs/horses). Instead, I've observed that all of them scuttle which constrains their maximum velocity. And after ...
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### torque needed to precess the angle of rotation

If a rigid body with the inertia matrix $I_B$, has the angular velocity $\overrightarrow{\omega_1}$ what torque is needed to rotate it around another axis say $\overrightarrow{\omega_2}$ while keeping ...
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### How is the Dirac delta function used in classical mechanics? [closed]

If the contact force applied to a physical object (ex. empty bucket) is given by the Heaviside function: $$F(t) = F_0~H(t)=\begin{cases} 0, t<0 \\ F_0, t \geq 0\\ \end{cases}$$ Then,...
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### On an inclined treadmill, does it help to “hang” on the bar?

I was a the heart specialist yesterday, and they wanted me on the treadmill, and they increased the incline to 15'. To counter the incline I hung back on the bars they wanted me to keep a hold on so ...
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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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### Rocket Propulsion Equation: Meaning of Net Force

Upon deriving the rocket equation, my textbook (Giancoli) states that the meaning of the net force on the final equation is the net force on M. Note that $M$ and $dM$ are used as the rocket (without ...
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### Condition of an object to slide off a sphere [duplicate]

An object is placed at the top of a smooth sphere of radius $R$. The block is released from rest. What is the angle with the vertical at which it looses contact to the sphere? I found this problem ...
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### How does mass affect slipping of a rolling object?

I experimented by rolling a cylinder down a tube and noticed that by increasing its mass, it's time taken to reach the bottom decreased. Found out that mass doesn't actually affect the time taken, ...
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### Change in gravitational effect between Earth and the Sun

SPOILERS FOR "INDEPENDENCE DAY: RESURGENCE" ABOUND. I just watch ID:R and had a question about a plot point. In the movie, a large alien ship, which looked to be about 10-20 percent the size of Earth ...
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### Simple harmonic motion mass between 2 buildings

I have a question, where I have a mass on top of a building, we give it initial velocity of $\sqrt{gd/2}$ then it starts colliding between 2 buildings, elastic collision. I have to find how many times ...
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### How to calculate the mechanical energy of a planet orbiting a Sun in a ellipse orbit? [closed]

I learned how to calculate the energy of the planet orbiting in a circle. then what about ellipse? I mean, why does the planet's energy is same when we model the planet's orbit into a circle which the ...
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### Circular Motion. Intuition on vectors as a physics interpretation [closed]

I am a maths undergraduate. I decided to start studying some basic physics trying to be rigorous with the math and uderstand the interpretations of some of the mathematical constructs and see how ...
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### Momentum and relative motion

To calculate momentum, $p=mv$, you must know the value of $v$. However, since all motion is relative, there is no abslute value for $v$. So, what is it you are actually calculating? It seems like the ...
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### question on friction, 3 blocks placed one upon another

A 10 N force is applied on the 3 kg block. What are the accelerations of the 2 kg block, 3 kg block and 7 kg block? Take the value of g=10m/s^2. what is the acceleration of each of the block ? ...
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### Is it valid to approximate this parabola as a circle?

Suppose I have a smooth parabolic surface on the xy plane, $y=-x^2$, and there is a ball on kept on the surface at $(0,0)$. What minimum velocity should I give to the ball, tangentially, so that it ...
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### Particle Equilibrium and the Interpretation of Accelerations

I have a simple question regarding the interpretation of acceleration and force in the context of a particle in equilibrium. Given that the necessary and sufficient definition for particle equilibrium ...
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### Do we not need a Zeroth Law of motion similar to the Zeroth Law of Thermodynamics? [closed]

Is the Zeroth Law of Thermodynamics necessary? If so, then do we need a similar law for motion?
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### What is the connection between inertial/gravitational mass and relativity?

In Einstein/Infield 's The Evolution of Physics (32-35) the authors establish that inertial mass and gravitational mass are the same and then connect this to relativity.Throughout these pages I was ...
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### Oscillations in U-tube [duplicate]

U-tube, of uniform cross section $S$ and opened at both ends, is filled with a liquid column of length $L$ and density $\rho$. In equilibrium the water levels in both arms are at same height. What ...
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### Why do rope walkers always carry a long stick with them?

I saw in the film The walk a guy who used to go from one high building to another via a rope. He carried with him this long stick. You´ll probably all know what I ...
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### Mechanics of a nut and bolt [duplicate]

Can somebody please explain how the rotary motion of a nut causes it to move upwards along a bolt. I tried to imagine it like an inclined plane but I still can't figure it out.
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### Does cutting of trees affect spin angular momentum of earth?

Cutting trees reduces earth's moment of inertia. So the spinning velocity of earth should be reduced day by day. Does it really happen?
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### Why do we assume Kinetic friction to be constant?

My Physics teacher told me that friction exists because of bonds made between the surfaces of two objects. As we try to move an object, we break the bonds and this causes release of energy which is ...
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### What does the Moon's orbit around the Sun look like?

I'm curious as to what the Moon's orbit around the Sun looks like. If there's an answer, what's the intuition for it? Here are some things I'm assuming when trying to tackle this question: The Moon'...
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### Find the trajectory of a Particle moving in a rotating tube [closed]

Problem: A straight smooth tube revolves with angular velocity $\omega$ in a horizontal plane about one extremity which is fixed. If at $t=0$ a particle inside it be at a distance $a$ from a fixed ...
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### theoretical explanation for smaller Young's modulus of silicone foam

I measured the Young's modulus of a rectangular silicone foam sample which is equivalent in material constitution to silicone rubber except that it is 80% empty. The Young's modulus for this foam was ...
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### Is the magnitude and direction of gravity on an object the same as the objects vertical velocity?

I need to make a diagram for an entry level college physics class. I need to show the magnitude and direction of gravity on a flying object and also show the magnitude and direction of the objects ...
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### Can rotational velocity be transformed into directional movement?

If I attach a weight to a string, and spin it, I notice that the faster I spin it, the more it pulls away from me. So, I imagine what would happen if I arranged a very large machine, designed so that ...
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### Must entangled particles be connected by some means to stay entangles

The people on this site are far more knowledgeable than I am and I probably don't belong here but my questions always seem to get answered to my satisfaction and I end up learning something. I have ...
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### Tuning fork clanging mode: boundary conditions?

The equation of motion of a tuning fork tine is given by: $$EI\frac{\partial^4z}{\partial x^4}+m\frac{\partial^2z}{\partial t^2}=0$$ or in shorthand: $$EIz_{xxxx}+mz_{tt}=0$$ Boundary conditions: z(...
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### Inertial Reference Frames (Newtonian Mechanics)

I have a hard time understanding Inertial Reference Frames. Is it just scenarios where Newton's laws seem to be violated in the case of non-inertial frames and where Newton's laws are followed in ...
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### How to determine my position using Coriolis effect?

The Coriolis effect is the effect that causes wind and water and moving objects to curve clockwise in the northen hemisphere and anticlockwise in the southern hemisphere, so how to determine my ...
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### Impulse in perfectly elastic collision

I am implementing this simplified model at the moment, and I am trying to get my head around the physics concepts behind this model. Event-Driven Simulation So the model has two parts, first is ...
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### Bigger tire/Smaller Tire

On a track, bigger tires have more contact therefore more traction. However, it comes at a cost of more unsprung weight. Therefore, the 0-60 time is slower as tested by Car And Driver. This was tested ...
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### How far would an arrow go in a space station and still be deadly?

So I was answering a question on the WorldBuilding SE site and one aspect of my answer made me wonder. Imagine you are on a massive space station of unlimited size. If you were to fire an arrow from ...
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### Orbiting in space

Background I'm making a game where a spaceship needs to orbit another object in space at a set distance. Space is, unlike other game, like space is in reality. Friction less. (at least to my ...
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### What would happen if a ball flew through the open window of a car?

I asked a science teacher this question a while ago but I did not receive a clear answer. Now, I was hoping someone on this Physics site could shed some light on my conundrum, I've been wondering for ...
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### about the motion of electrons inside the atom [duplicate]

My question is very basic question.I am somehow not able to understand it. bohr's theory says that the electron can only revolve in orbits which they have quantised angular momentum so they must ...
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### Pseudo acceleration when both observer and observed body are accelerating and also the surface is accelerating

Today we were taught us the concept of pseudo forces.I understand that suppose when the observer is in an accelerated reference frame to make newtons laws valid we consider an acceleration in the ...
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### Meaning of the Value of Centripetal Acceleration

In the traditional sense, acceleration means the rate at which velocity is changing. Visually, we tend to associate this with the magnitude of velocity. If the centripetal acceleration of the moon ...
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### Feynman's explanation of virtual work given in his book Feynman's lectures on Physics

In his book Chapter 4 Conservation of Energy, on Gravitational potential energy the discussion goes... "Take now the somewhat more complicated example shown in Fig. 4-6. A rod or bar, 8 feet long, ...
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### Two carts on a frictionless rail collide [closed]

There're 2 carts on a frictionless rail. Their masses are $4m$ and $2m$. (The carts are on the rail in this order). The first cart has a velocity of $v_1$. The first cart hits the second. Knowing that ...
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### Friction in circular motion?

Let us imagine a car (or just a block) moving in uniform circular motion with radius $R$ with velocity $v$, on a flat surface. It is obvious that friction is the only force capable of providing the ...
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### Seesaw pendulum period

If I have a rigid pendulum of length $L$, with the pivot point set somewhere along $L$ and a mass at each end how do I calculate its maximum speed and its period? I want to make a counterbalanced slow ...