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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4answers
277 views

How to solve this problem without using energy conservation

I believe most of you probably solved the following problem using energy conservation as shown here. It states a block of mass $m$ sliding on a sphere of radius $R$. I've be trying to solve this ...
0
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3answers
58 views

Why does overcoming inertia depend upon time?

When a paper over a glass is pulled suddenly, the coin over it falls to the water. But on pulling it slowly, the coin gets pulled along with the paper. Why does the coin in the former case not feel ...
0
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1answer
64 views

How to prepare mental skills to understand relativity theory? [closed]

Upto the high- school, I had to admit and write-on-exam the strange, counter-intuitive statements of relativity theory; those I could not believe. Now, I'm not a physics or math-student, (and indeed ...
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1answer
44 views

Notations used to express direction [closed]

We express direction relative to a reference point and call a certain direction positive and it's direct opposite direction negative, by convention. But, what notation should we use to express a ...
1
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1answer
35 views

Work done relation to potential energy

I know work done is negative of change in potential energy, I.e., $W=-(∆U)$. It means that Work done against a force (or work done on a system) increases its potential energy. And Work done by a ...
0
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2answers
82 views

If I throw or kick a ball, how much will the Earth move in the opposite direction?

I understand that for momentum to be conserved, if I throw a tennis ball (or kick a football) the Earth must move in the opposite direction to the ball. Obviously this is an infinitesimally small ...
0
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1answer
120 views

Is conservation of momentum and energy valid for non-inertial frames?

Conservation laws of momentum and energy are said to be the most basic principles of physics. Are they also valid for non-inertial frames, and in what way?
0
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1answer
30 views

Where does gravity get it's energy to cause tides? [duplicate]

The moon's orbital radius is fixed as a function of its velocity (I know it is actually drifting..). Since there is nothing in space to resist this velocity, it will continue orbiting "forever". Now ...
1
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0answers
28 views

Generalise Noether's theorem [closed]

I'm not sure how to generalise Noether's theorem. For this L, I think $B\cdot\dot{x}$ is conserved so I tried to relate F and K to this and try to show that that was conserved but got no where. any ...
2
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2answers
111 views

Equation for a falling body including terminal velocity

I'm making an app that times how long it takes a pebble to fall, then calculates the distance it fell. I noticed that the simple $f(t) = \frac{1}{2}gt^2$ was becoming increasingly inaccurate as the ...
4
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7answers
169 views

Why does a rigid body rotate and not simply translate when pushed with an instantaneous force?

Let's say we have a metal rod of consistent density sitting flat on a frictionless surface. I intuitively understand that if I push one of its ends away from me, (at a right angle to the length of the ...
0
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2answers
35 views

Discrete form of deformation gradient from vectors with finite length

I am writing some code for a deformable mesh and need to calculate a local deformation gradient within the material by using the vectors connecting material points. I think the method of solving ...
0
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0answers
28 views

Average of the velocity vector along a Keplerian orbit

I would like to show that the average of the velocity vector $\mathbf{v}$ along one Keplerian orbit vanishes, i.e. $$ \frac{1}{2 \pi}\int_{0}^{2 \pi} \!\!\!\! \mathrm{d} M \, \mathbf{v} = \frac{1}{T}\...
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1answer
26 views

Calculating the work done by friction on a rigid body due to the piston

I have a uniform rod of length 0.5m and mass 0.1kg, and on this rod are two balls of mass 0.03kg both at a distance of 9.997cm away from the center of the rod. There is a pin about the center of the ...
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2answers
62 views

Speed and motion

If you your traveling in a forward motion at a certain speed and throw an object in the opposite direction at the same speed shouldn't it fall straight down to the ground.
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1answer
58 views

Newton's 2nd Law with Dirac Delta, as a way to derive the Ideal Gas Law

I'm trying to derive the ideal gas law from first principles, namely that a particle bouncing off a wall will exert a force on the wall. Newton's second law $F=\frac{dp}{dt}$ relates the force an ...
1
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1answer
73 views

Understanding Newton's Laws of Motion

I'm having difficulty understand Newton's laws of motion in practice, and how to model true dynamic systems. There are two examples below, where I cannot quite figure out what the true forces and ...
1
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2answers
50 views

Can a system's internal forces change the system's motion?

Let say the motor makes the two rigid body rotate as a same velocity. (they rotate the opposite direction) then the Net force of the motor is 2Fsin(Theta). The acceleration of the motor is 2Fsin(theta)...
1
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1answer
46 views

Which one would has a greater magnitude, the viscous drag or the weight of the bubble?

An air bubble in a tank of water is rising with constant velocity. The forces acting on the bubble are X, Y and Z as shown. What describes the three forces? A) Z is the viscous drag ...
0
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2answers
57 views

Bob on a cart problem

(sorry for the shabby figure!) The problem-a bob of mass $m$ is hanging from a cart of mass $M$. The system is released from rest from the position shown. Find the maximum speed of the cart relative ...
1
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1answer
34 views

How the data or models given in physics or mathematics problems can be obtained in real life? [closed]

When ever there is physics or mathematics problem. we are already given a mathematical model. Can't we make own models from given diagrams or data collected from the problem? sometimes angle is given ...
3
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2answers
96 views

Kepler Orbits: Small Perturbations->Elliptical Orbits

A group of my physics classmates and I have been stuck on this problem. We have tried a few approaches. The problem is to show that a body following a circular orbit, when given a small radial ...
0
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2answers
51 views

How to calculate energy loss in a rotating shaft?

Please help me with proper formula for below example. Imagine a rotating shaft 'X' with 2 gear wheels 'a' and 'b' of same dimensions. If energy applied to gear 'a' on the shaft through source A ...
0
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2answers
39 views

Wheel versus Sphere: Traveling Linearly Down a Track

Assume the following: A tire-like wheel and sphere are both of diameter d and mass m They are both made of the same material They are both resting at the apex of an inclined track An equal amount of ...
0
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0answers
56 views

Physical pendulum dynamics confusion

I'm validating a Matlab Simulink SimMechanics model analytically. The model consists of a physical pendulum (uniform rod with length $l$ and width $w$) which is torque driven. I'm somewhat confused ...
0
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5answers
103 views

Can there be an acceleration when no net force acts on a massless object?

If no net force acts on a massless object can there be any acceleration of the object? My attempt: $$F=ma\\ \implies a=F/m\\ \implies a=0/0 $$ $\implies a$ can be anything.
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0answers
31 views

In table tennis, is it possible to play a ball in such a way that it does not bounce off the opponents half of the table?

In table tennis you dont need to play over the net, the ball just has to hit the other half of the table. Is it possible to play the ball around the net so that it does not bounce off? My friend and ...
1
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1answer
123 views

When does a Trebuchet Shoot Its Projectile?

Consider the following sling trebuchet: While researching I found that what controls the release angle of the projectile is the angle between the 'finger' and the extension of the beam $r_b$, as ...
1
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1answer
70 views

Block resting on an inclined plane [closed]

A block of wood of mass 3 kg is resting on the surface of a rough inclined surface as shown in the image. We have to calculate the value of all the three forces. The solution says that frictional ...
0
votes
3answers
55 views

Can internal forces bring any change in momentum of the system?

Imagine a rectangular box placed at the tip of an iceberg; the box contains a man who can freely walk/jump/rotate inside the box. The man walks up to one of the corners of the box and starts jumping. ...
-1
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1answer
53 views

Confusion in differentiation in physics problem [closed]

Here, we had to find theta such that the denominator has the maximum value. Being new to differentiation I basically didn't understand how differentiation solved the purpose: I basically didnt ...
1
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4answers
63 views

How is frictional force dependent on normal reaction?

It is a general concept that horizontal forces can only influence physical quantities along horizontal direction; similarly vertical force can produce acceleration etc. only along vertical direction. ...
0
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2answers
43 views

Frictional Force on Plane Increases when Angle Increases?

I came across this question in one of my books and don't completely understand the answer: An object is resting on a board. One side of the board is slowly raised, up to an angle of 60 degrees. The ...
0
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1answer
28 views

Inertia for a large mass (in outer space)

I understand that an object doesn't need a force to keep moving; that it will keep moving indefinitely in that direction at that speed. My question though is: if you were in outer space, where ...
0
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0answers
59 views

Why does a velocity that gives gravity's centripetal acceleration make you stay in orbit?

Explanations of basic orbital mechanics that I can find all go, $$\frac{v_{satellite}^2}{r} = a_c = \frac{F_{gravity}}{M_{planet}} = \frac{(\frac{G M_a M_s}{r^2})}{M_{planet}}$$ , and so you get a ...
0
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1answer
31 views

Could we find the overall force and direction of something with a diagram only? (i.e. no calculation)

My friend, who is a geologist, and I were just debating some dynamics stuff. To make this easier, lets come up with an analogy......lets say there's a boat and it's being pulled by two smaller boats ...
12
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3answers
2k views

What are some phenomena that can not be described without the help of Newton's third law of motion? [closed]

What are some phenomena that can not be described without the help of Newton's third law of motion? All the phenomena I can think of can be explained with the help of Newton's first law or second law. ...
1
vote
1answer
30 views

Bifilar Pendulum Equation [closed]

This is my first post so I am not sure exactly how to do all the notation so this may be weird but please bear with. I am trying to finish my physics internal which I did on the effect of differing ...
0
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2answers
52 views

Newton's Third Law

Sorry if this question's been asked. I looked through some of the questions but didn't find a similar enough question. My question on Newton's Third Law: It's my understanding that if you were in ...
0
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2answers
41 views

Independence of Period and Amplitude in Simple Harmonic Motion

In Simple Harmonic Motion, the period $T$ of an oscillation, is said to be independent of the amplitude $A$ of an oscillation, but why is that so? Attempting to derive from the equations of Simple ...
0
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0answers
29 views

How to model muscle contraction force acting on two bones connected by joint?

I'm trying to understand what is a correct way to model a muscle contraction in a physics engine like PhysX (Unity3D). Muscle that I'm modelling is connected to a bones in 2 points A and B. Having a ...
0
votes
2answers
61 views

Force on a massless spring [closed]

Is classical mechanics applicable as to what extent F=dp/dt would make sense as p=0 but we are applying an external force,when a force is applied on one end of a massless spring while the other end is ...
0
votes
1answer
37 views

About energy in Simple Harmonic Motion

The problem is this; Given the amplitude A, find the a value of x for which the kinetic energy represents half of the total energy of the system. I have so far tried to relate A to a maximum ...
2
votes
1answer
123 views

Physics Chain Problem

A chain of length d lies on a table, $d/4$ of it hangs loose on the side of it. Friction coefficient is 0.2. It is released and begins to slide. What is the final velocity with which it falls of the ...
0
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1answer
20 views

Heliocentric to barycentric coordinates

I have a system with a central body and "particles" orbiting around it. The system is described in heliocentric coordinates. I am trying to obtain the velocity of the central body in barycentric ...
0
votes
1answer
60 views

Why did Newton state his first law separately even though it is apparently a direct consequence of the second law? [duplicate]

If $F=0$, $F=ma \implies m\frac{(v-u)}{t}=0\implies v-u=0 \implies v=u $ Which is essentially Newton's first law.
0
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1answer
36 views

The components of applied forces on the masses of a Trebuchet

Background information: I was following an online mechanics document in order to learn how to derive the equations of motion for a trebuchet (shown below) using Lagrangian mechanics. At some point ...
0
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1answer
22 views

Problem in understanding in the derivation of torsion acting on a circular shaft fixed at one end

My doubt is how Arc(ab) = L $\gamma$. Arc (ab) = R$\theta$ makes sense as that's the arc of that circle.