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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Spring damper model does not work very well [migrated]
I'm trying to model a spring damper system from a tutorial that I've found on this site.
If I use the exact same parameters as the ones in the tutorial the system is not stable. I've downloaded the ...
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0answers
23 views
Pulley system with rope
Two masses $m_1$ and $m_2$ are connected through a weighty, uniform and an unstretchable rope of length $L$. The surface is frictionless. Masses of the objects are $m_1=m$, $m_2=\frac{2}{3}m$, mass ...
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1answer
43 views
intuition contradicting answer for calculating pressure
I have a cylindrical container say of some base area $A$. The atmospheric pressure is $P_0$. The cylinder is moved at an acceleration $a$ horizontally right. I need to find which base would have to ...
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2answers
46 views
Momentum, Impulse and Newton's Second Law of Motion
Newton formulated his Second Law as such:
$$\sum{\vec{F}} = \frac{\delta \vec{p}}{\delta t}$$
and of course, $\vec{p} = m \vec{v}$.
Why is it that if the net force $\sum \vec{F}$ is constant (which ...
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1answer
47 views
How do determine the equation of motion of slinky?
I'm trying to analyze the forces exerted to slinky. First, I've divided both ends.
The red vector is the force exerted by slinky itself, and the green vector is gravitational force.
Force exerted ...
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1answer
35 views
Problem with a rotating frame of reference on the South pole
Consider this problem:
A high-speed train is traveling at a constant 150 m/s (about 300 mph)
on a straight horizontal track across the south pole. Find the angle
between a plumb line suspended ...
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2answers
71 views
How can a car's engine move the car?
Newton's First Law of Motion states that an object at rest or uniform motion tends to stay in that state of motion unless an unbalanced, external force acts on it.
Say if I were in a car and I push ...
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1answer
45 views
Friction on a conveyor belt
I was surfing through an Olympiad paper and I was caught with this question-
A block of mass 1 kg is stationary with respect to a conveyor belt that is accelerating with $1\, \tfrac{m}{s^2}$ ...
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4answers
167 views
How can I determine whether the mass of an object is evenly distributed?
How can I determine whether the mass of an object is evenly distributed without doing any permanent damage? Suppose I got all the typical lab equipment. I guess I can calculate its center of mass and ...
3
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0answers
49 views
Effective mass in Spring-with-mass/mass system
Suppose you have a particle of mass $m$ fixed to a spring of mass $m_0$ that, in turn, is fixed to some wall. I'm trying to calculate the effective mass $m'$ that appears in the law of motion of the ...
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1answer
27 views
Static friction force on a block in a tunnel
Linked to this Comparing Static Frictions
Suppose there is a cuboidal vertical tunnel , and a cubical block in it such that all surface of the block are in contact with the four walls of the ...
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1answer
34 views
If An Object Explodes With A Force, What Force Are Fragments Given?
So let's say for example I have an object with 5kg of mass.
It explodes with a force of 500N.
The object fragments into four fragments: a 0.5kg, a 1kg, a 1.5kg and a 2kg object.
What force does ...
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1answer
62 views
Vector cross product of $\mathbf{r}$ and $\ddot{\mathbf{r}}$ in polar coordinates
I'm struggling with the following question:
Question 6 A planet of mass $m$ moves under the gravitational attraction of a central star of mass $M$. The equation of motion of the planet is
...
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0answers
19 views
newton's laws - involving block and conveyor belt [closed]
i was surfing through a physics book when i encountered this problem-
A block of mass 1 kg is stationary with respect to a conveyor belt that is accelerating
with 1 m/s^2 upwards at an angle of ...
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0answers
32 views
Lagrangian with a general constraint [closed]
Can any body help me out to solve this problem?
I am familiar with mechanism of Lagrangian and I can solve some problems with constraints but this one is really hard to solve.
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4answers
121 views
Is it possible to whirl a point mass (attacted to a string) around in a horizontal circular motion *above* my hand?
I'm studying circular motion and centripetal force in college currently and there is a very simple question but confuses me (our teacher doesn't know how to explain either :/), so I hope we can sort ...
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1answer
24 views
A rod of length $L$ & mass $M$ is rotating in a circle about one end then calculate tension in the rod at a distance $x$ from the support
A rod of length L & mass M is rotating in a circle about one end then calculate tension in the rod at a distance 'x' from the support ?
For its solution why should we take mass of L-x portion of ...
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1answer
35 views
Another Inclined plane question
I did the FBD, and I found too many variables which are not eliminating...Moreover, I believe this question is based on kinetic and static friction. But, $\mu$ here is ambiguously defined...How Do I ...
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3answers
30 views
The motion of a spring
I have a question about the force set by this spring, I saw many times that $\overrightarrow{F}=-Kx\overrightarrow{i}$.
I'm asking why not using $\overrightarrow{F}=Kx\overrightarrow{i}$ without the ...
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1answer
47 views
Comparing Static Frictions
In this figure, which of the static frictional forces will be more?
My aim isn't to solve this particular problem but to learn how is static friction distributed . Since each of the rough-surfaces ...
4
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3answers
100 views
Moment of Inertia (triangular plate)
I want to generalize the formula for the MOI of a triangular plate (sides $a,b,c$) about an axis passing through mid point of one sides and perpendicular to it's plane .
The mass of plate $M$ is ...
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2answers
56 views
Massless string Paradox
If we introduce the notion of a massless string to denote the fact that net force on a massless string will always be $0$, since it is massless . How can these massless strings ever accelerate when ...
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1answer
55 views
Work done by Static friction
Here $v1$ is relative to the block on which sphere is pure rolling but static friction isn't $0$ as of now .
In the following diagram, is work done by static friction $0$ ?, since the point of ...
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1answer
46 views
Boundary conditions on wave equation
I am having trouble understanding the boundary conditions.
From the solutions, the first is that $D_1(0, t) = D_2(0, t)$ because the rope can't break at the junction.
The second is that ...
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4answers
97 views
Potential energy sign conventions
Almost every book on physics that I read have some weird and non-clear explanations regarding the potential energy. Ok, I do understand that if we integrate a force over some path, we'll get a ...
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2answers
66 views
Centripetal Force Acceleration
Suppose you want to perform a uniform circular motion . Then a body performing uniform circular motion horizontally needs an acceleration $= \frac{v^2}{r}$ at each point on the circular path with ...
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1answer
54 views
Physics of the point of contact for a spinning top
I understand how spinning tops don't tip over, cf. e.g. this and this Phys.SE questions. What I'm more interested is in identifying the factors that determine the direction the spinning top moves to?
...
5
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1answer
61 views
In tennis, why does topspin serve bounce higher than flat serve?
When receiving servers (while playing tennis), I've noticed that the tennis ball seems to bounce up higher on me when the server uses a topspin serve than when the server hits a flat serve. Why is ...
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0answers
50 views
A slender rod with a ball at the end
A slender rod is attached to a block accelerating horizontally. The rod is free to rotate without friction. At the end of the rod is a ball.
As the block accelerates, the slender rod will be deviated ...
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0answers
46 views
Object on an inclined plane
I was solving a question about inclined planes, and it got me thinking:
Imagine a scenario where, an object is on an inclined plane and the inclined plane is on a frictionless surface, and is itself ...
3
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4answers
114 views
What do people actually mean by “rolling without slipping”?
I have never understood what's the meaning of the sentence "rolling without slipping". Let me explain.
I'll give an example. Yesterday my mechanics professor introduced some concepts of rotational ...
5
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1answer
145 views
How reliant is the Solar System on being exactly the way it is?
We know that all objects with mass exert forces on all other objects of mass such that
$$ F = \frac{GMm}{R^2}.$$
And as others have discussed the planets do interfere with each other ...
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1answer
56 views
Tension in a closed loop around an object, carrying stuff
Sorry when this sounds like a first year physics homework question, but it's actually not. It arose during a discussion regarding safe practices for rock climbing anchors...
So here we go: Imagine ...
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0answers
46 views
What force does the seat exert on the rider at the top and bottom of the ride? [closed]
A 75 kg person rides a Ferris wheel which is rotating uniformly. The centripetal force acting on the person is 45 N. What force does the seat exert on the rider at the top and the bottom of the ride?
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1answer
45 views
A theoretical problem on Mechanics [closed]
Two particles with masses $m_1$ and $m_2$ are moving in 3D space with some Cartesian coordinate system. There are known the laws of motion of these particles, i.e. the position vectors $\vec{r_1}(t)$ ...
4
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1answer
98 views
Chain of balls on an inclined plane
Suppose we have some inclined plane, and there is some chain of balls of length $l$ and mass $m$ lying on it. No friction at all in the system.
1) What is $x_0$ (the vertical hanging part of the ...
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1answer
62 views
Centripetal force and circular motion
I have a doubt, say when a body moves in a circular loop, there are basically two types of acceleration acting on the object. One is the linear acceleration which is basically tangent to the circle, ...
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2answers
60 views
Why is potential energy negative when orbiting in a gravitational field?
I had to do a problem, and part of it was to find the mechanical energy of satellite orbiting around mars, and I had all of the information I needed. I thought the total mechanical energy would be the ...
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1answer
80 views
Initial position and velocity of rocket to escape earth's gravity
I'm trying to numerically simulate a spacecraft trajectory between earth and mars. I already wrote the solar system model where the sun is at the origin of the x,y,z plane Earth and Mars are orbiting ...
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5answers
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Why Won't a Tight Cable Ever Be Fully Straight?
I posted this picture of someone on a zipline on Facebook.
One of my friends saw it and asked this question, so he could try to calculate the speed at which someone on the zipline would be going ...
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0answers
46 views
Work And Energy Question [closed]
$H = 3\text{ m}$,$m=2\text{ kg}$
The right side is rough.
I want to figure:
what is the coefficient of friction $\mu$?
How high and exceed the maximum return on the plane right body?
I know ...
1
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1answer
52 views
SHM of floating objects
If we consider an object undergoing who has an acceleration proportional to the displacement of the object, it is going simple harmonic motion.
In terms of Newton's second law, this is $$ -\dfrac k ...
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2answers
50 views
Constant of gravity in earth fixed coordinate system
I have this problem:
If the constant of gravity is measured to be $g_0$ in an earth fixed
coordinate system, what is the difference $g-g_0$ where $g$ is the
real constant of gravity as ...
5
votes
0answers
68 views
+50
How multiple objects in contact are resolved in an inelastic collision, when edge normals don't “line up”
In a case I understand, let's say I have an object A moving at velocity V toward 3 objects in contact B, C, and D:
The momentum of A is the mass of A times its velocity. To figure out how the ...
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2answers
43 views
Simple conservation of momentum and frame of reference problem
I'm making a very simple physics engine based on momentum, and I'm solving what response to use for a collision from each involved object's frame of reference. However, something about how I'm ...
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2answers
47 views
Center of mass problem
According to the definition of potential energy, we use $U= mhg .
$
In the figure below ,
A thin uniform rod of mass m and length h is positioned vertically above an anchored frictionless pivot ...
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0answers
30 views
Velocity versus time graph [closed]
A stone is thrown at an angle of $45^0$ above the horizontal x-axis in the +x-direction. If air resistance is ignored, which of the velocity versus time graphs shown above best represents $v_x$ ...
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2answers
54 views
Angle between acceleration and velocity
Problem:
A particle is constrained to move in a circle with a 10-meter radius. At one instant, the particle's speed is 10 meters per second and is increasing at a rate of 10 meters per second ...
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2answers
78 views
Are there problems solvable with Newtonian physics, GR and QM?
First I must let you know that I don't have much understanding of neither GR nor quantum mechanics, and therefore this question.
I've mentally pictured Newtonian physics, GR and quantum mechanics all ...
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2answers
52 views
Time period for spring connected body
Two identical springs with spring constant $k$ are connected to identical masses of mass $M$, as shown in the figures above. The ratio of the period for the springs connected in parallel (Figure 1) ...
