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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2answers
57 views

Would there be a “freefall zone” in the centre of a centrifugal artificial gravity?

In the novel Schismatrix, Bruce Sterling writes about people living on the inside of rotating cylinders (similar to Larry Niven's Ringworld and Iain M. Banks' Orbitals, but the atmosphere extends ...
0
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1answer
30 views

Expressing angular velocity of solid body [closed]

The problem: We have a circular disk of radius $R$ and mass $M$ that is mounted on a rotation axis that is not the axis of symmetry of the disk. The moment of inertia with respect to the axis of ...
1
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1answer
34 views

Reference frame and conservation of energy

Say spaceship $\alpha$ burns a portion of its fuel to leave planet A and is cruising through space at 10 m/s relative to the surface from which it launched. Spaceship $\alpha$ is being observed by ...
1
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1answer
67 views

In perfect vacuum (no external force), if I apply a small amount of force to a body, will it continue to accelerate forever?

According to the equation F = ma, the greater the force applied to a body, the more is it's acceleration. But in a place where there is no gravity or any other kind of external force, If I apply a ...
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1answer
15 views

Will the speed of a non-servo convey belt be affected by its load?

By non-servo I mean that the motor has no feedback loop to maintain constant speed. Also, may we ignore the load itself causing extra friction? Assume the belt is made of a material tense enough to ...
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1answer
52 views

Gravitational Potential Energy misunderstandings [closed]

I'm really confused by the derivation of Gravitational Potiential Energy. I took a screenshot of the wikipedia entry below. My major confusion lies in: 1. The use of the position vector r in the ...
0
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3answers
66 views

How is Earth orbit possible? [duplicate]

What force other than gravity acts on objects in Earth orbit? Without such force, continued orbit would be impossible, as the object would be drawn to the Earth.
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1answer
27 views

Understanding the constraint of tension with a rigid body

I want to know why doesn't $T_1 = T_2$? I think its probably because of the Pulley but still aren't the Tensions Equal but opposite in direction.
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0answers
23 views

Derivation Poisson's gravity equation by divergence theorem

I'm trying deduce the poisson's equation $\nabla^2\Phi (x)=-4\pi G\sigma(x)$ by divergence theorem Let $D:x^2+y^2+z^2\leq 1$ and $\sigma:D\to \mathbb{R}$ be the mass density function of $D$ (suppose ...
3
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2answers
97 views

How mass is determined in dynamics?

Mass is one of the most core and complicated concepts in dynamics. I have tried many books but I still don't have a good idea of how the mass of any object is determined relative to another. In The ...
0
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1answer
22 views

When an object hangs from a Rigid rod is the force of the weight located in the center of the sign?

From the rope that supports the sign (assuming the mass is distributed evenly). If the length of the sign is, $L$ can I model it so that the weight is concentrated at $\frac{L}{2}$ Therefore, the ...
0
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2answers
105 views

Orbital mechanics: will a satellite crash?

For a satellite given an initial speed and position above a planet, I'd like to know whether it will experience an elliptical, circular, parabolic or hyperbolic trajectory, or crash into the planet. ...
0
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1answer
12 views

Calculating the RMS angle of a driven oscillator

We are given that the oscillator obeys the following DE: $\ddot{\theta} + \omega_0^2\theta = \text{cos}(\omega t)$. The solution is $\theta = Ae^{i\omega_0t} + Be^{-i\omega_0t} + ...
0
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1answer
13 views

Interaction pairs- how they can cause movement

Back to basics with this question but I really want to make sure I understand this concept. Newton's third law states that 'every action has an opposite and equal reaction', which we can see through ...
1
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0answers
21 views

DIY ultrasonic cleaner - will it work? [closed]

I want to build some simple ultrasonic cleaner and I wonder: is my idea going to work? The plan is: Build a container from metal sheets or just find/buy some container. Buy something like 60W 40 kHz ...
0
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1answer
39 views

A sphere rolling down a plank - an error in calculating its energy

Consider the following situation: A sphere with radius $r$ rolls down a plank which forms an angle $\theta$ with the horizontal axis. The starting hight of the centre of mass is $h$. We assume that ...
1
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2answers
61 views

Question about the wave function of a travelling wave

I have a confusion about the wave function of a travelling wave. Suppose we have a wave function of a travelling wave travelling towards the positive direction of x axis $$ ...
1
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0answers
26 views

Calculating torque needed to climb a graded hill [closed]

this is my first post but I'll try to give my best understanding of the problem. I've been designing an electric skateboard which is driven by only one of the rear wheels (for the moment). As I was ...
1
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1answer
35 views

Help with my bouncy ball lab (I know the factors just not how to approach them) [closed]

In my physics lab we need to determine the factors that account for the energy "loss" during a high bounce ball bounce. I know that energy is "lost" (not really) to heat, air resistance, and sound. ...
1
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2answers
48 views

Sliding along a circular hoop: work done by friction

Assume a point object of mass $m$ slides along a hoop of radius $R$, starting from a position which makes 90 degrees with the line of radius connecting the center and the ground. Let the ...
0
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0answers
11 views

compound bars in series

Compound bars 1 and 2 have lengths L1 and L2, areas A1 and A2, Young moduli E1, E2,thermal expansion coefficient a1 and a2. subjected to a change of temperature T. Two ends of the bar are fixed. The ...
2
votes
1answer
51 views

The source of work by gravity force [duplicate]

I learn that any work needs a source of energy, the work of gravity force (like keeping the Moon in the orbit by the Earth gravity force) comes from where? Can we find any mass reduction (transform ...
-1
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1answer
36 views

Composite bar in series paradox

2]2 Here is the progress and the problem that I encounter. I can calculate the tensile force but it seems like the force cannot exist in the first place ? P/s: I am sorry because I can only pose the ...
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0answers
23 views

Sign of elastic potential from a spring [closed]

When writing the Lagrangian of a problem, how do I determine the sign of an elastic potential from a spring?
2
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1answer
46 views

Changing the length of a spring [closed]

Imagine we have a spring that is hanging from the roof with $k = 200$ and a stone with $ W=10N $ is pulling it down. Then due to $$ F=kx $$ we have $x=.05m=5cm$ Now we halve the length of the spring. ...
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0answers
37 views

Free Falling Bodies [closed]

An object is thrown vertically upward. It has a speed of 10ft/s when it reached one-half its maximum height. since this is a thrown object it's initial velocity is a mystery, is it right to make ...
0
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1answer
29 views

Falling objects with different masses

I know that free falling objects with different masses fall at the same rate but that does not explain why objects with big masses are heavier to lift? what is gravity anyway I know it isn't a force ...
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2answers
80 views

Optimal curve for a marble drop [closed]

I'm doing a marble roller coaster project for my physics class at school. The first part of our roller coaster involves a marble falling downwards into a curve that will drop then go up 12 inches. ...
0
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2answers
62 views

Finding equation of motion for a two mass one spring system

I'm trying to find the equation of motion for the system below. As you see, there is a trailer connected to a car with a spring. There are a "b.v" force where b representing a coefficient of ...
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3answers
89 views

If we consider the electric field to act upon charges with a force, how does it stay in line with Newton's laws?

This should be a relatively simple question. Let's say we have a constant electric field $\textbf{E}$ in a conductor. The electric current density would then be $$\textbf{j}=\rho \textbf{v}$$ where ...
5
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5answers
1k views

Why do objects in a gravity simulation experience sudden large accelerations?

I'm trying to create a simple program that simulates gravity. The idea is that I have one central sun and several planets that I can create with a swipe gesture on the screen, and I use the initial ...
1
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0answers
26 views

Two compound bars connected in series hanging vertically [closed]

I have a steel and a copper connected in series. We know the original length, cross area and young modulus of both bars. Now we hang it vertically, connected the upper end of copper to the ceiling and ...
0
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1answer
46 views

Inelastic collisions

During inelastic collision the kinetic energy does not remain constant. In many texts, I have seen it is because there is loss in energy from the system. If there is loss in energy, then how can mass ...
0
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0answers
26 views

Calculating electricity used for weights on an elevator

Given an elevator with a motor driven by a power supply, torque ability and a pulley does it take more electricity to lift more people? I have some of the calculations but do elevators lift at a set ...
12
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5answers
1k views

What force causes the ball to move up?

Let's consider this super-simple example. The ball (mass $m$) is moving from position 1 to position 2 at constant horizontal velocity $v$ until the ball reaches the red arrow (in position 1, it has ...
2
votes
1answer
71 views

How accurate is Newtonian mechanics? [closed]

How accurate is (theoretical, i.e. the mathematical formulation basing on "formalised" physical constants, such as material density) Newtonian mechanics? What does the accuracy depend on (material ...
0
votes
1answer
45 views

Calculate the change in mechanical energy for a system in presence of friction [closed]

The two masses in the figure are released from rest. after the $3$ kg mass has fallen $1.5$ m, it's moving with speed of $3.8$ m/sec. what is the change in mechanical energy done on the system during ...
24
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7answers
3k views

If I toss a coin, vertically, on the surface of Mars, will it land back in my hand?

When I toss a coin in Mars, is the planets atmosphere rare enough that I'd rotate with the planet (at its angular velocity), but not the coin?
0
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4answers
123 views

Driving on the moon

I think that a car which is applying its max force on Earth stops accelerating (as in, stops increasing in speed) because of air resistance. But on the moon there is none so I think the car would ...
1
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6answers
88 views

Physical explanation for different angles yielding the same range in projectile motion

It's well known that throwing a ball with a given speed at angles alpha or (90-alpha) will get it to land in the same distance. It's easy to see from the equations, but is there a more physical ...
1
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0answers
29 views

Unfamiliar force of friction in materials [closed]

I have never faced with questions that friction effects more than two time until last week that one of my friends gave me this question : We have two surfaces : Sur1: with coefficient of static ...
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votes
1answer
37 views

is it viable to pump water with wind before turning it into electricity? [closed]

If one was to place many [short] turbines along a windy bridge, a levee or a windy road could one remedy the losses from many small generators, low voltage and large distances by pumping water in ...
1
vote
2answers
65 views

What would happen if the gravitational force was repulsive? [closed]

Since my young age, I have always been somewhat afraid of looking up at the sky for one weird reason. It always made me think about this irrational deep dark fear that I have: What if we stopped ...
1
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0answers
25 views

How can a net force of 0 still lead to movement and how is movement possible with interaction pairs? [duplicate]

So I always thought of movement as interaction pairs. For example, I thought that a rocket moves by applying a force of hot exhaust gases, which then apply a reaction force back on the rocket ...
1
vote
1answer
30 views

Does Earth rotation effect planes? [duplicate]

What about the supposed aiming modifications when firing a weapon? According to my research, when firing a weapon you are supposed to aim a little to the right when firing northwards and to the left ...
1
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3answers
66 views

Violation of Newton's third law

consider the following situation shown in the diagram below.A huge wall of mass M is moving to the left due to a constant force of 100N. Now suppose a man of mass m applies a force of 20N to the ...
0
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1answer
25 views

Dilemma on work done by gas in isothermal contraction

Consider an ideal gas inside a cylinder undergoing reversible isothermal contraction. Now if we consider the forces acting on the gas inside the cylinder the force acting is $P_{ext}\cdot A$, however ...
-1
votes
1answer
34 views

Wave oscillation [closed]

A 2 kg block is attached to a spring for which $k=200N/m$ . It is held at an extension of 5 cm and then released at t=0 , Find a, the displacement as a function of time and b, the velocity when ...
0
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1answer
48 views

Moment of inertia of orbiting sphere

Is the moment of inertia of a sphere orbiting some object equal to the moment of inertia of a point mass at the same distance away from the object?