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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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 $\vec{r_1}(t)$ ...
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1answer
103 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
65 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 ...
1
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1answer
85 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
50 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 ...
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1answer
59 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
55 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
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0answers
80 views
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
46 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 ...
1
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2answers
51 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
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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
56 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 ...
1
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2answers
79 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
58 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) ...
1
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0answers
38 views
impulse problem [closed]
The figure above shows a plot of the time-dependent force $F_x(t)$ acting on a particle in motion along the x-axis. What is the total impulse delivered to the particle?
...
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1answer
56 views
Why body starts moving when force is applied? [duplicate]
The recent question by m.buettner regarding self-inductance and its resistance to EMF Faraday's law - does the induced current's magnetic field affect the change in flux?, recalled me the ...
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0answers
38 views
A space vehicle travelling at a velocity of 1296 (km/h) separates by a controlled explosion into two sections of mass 7276 (kg) and 236 (kg) [closed]
A space vehicle traveling at a velocity of 1296 (km/h) separated by a controlled explosion into two sections of mass 7276 (kg) and 236 (kg). the two parts continue in the same direction with the ...
1
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3answers
66 views
Relation between the time, velocity and acceleration
This is question from I.E. Iredov's General Physics:
$1.22$ : The velocity of a particle moving in the positive direction of the $x-axis$ varies as $v = α \sqrt x$, where $α$ is a positive ...
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2answers
55 views
Pressure in fluids
Fluids exert hydrostatic pressure because their molecules hit each other or the immersed body . But why is that at a greater depth pressure is higher when molecules are the same .
Assume density of ...
13
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1answer
199 views
Modelling the movement and jumps of a chalk while drawing a dashed line on a blackboard
You probably know that if you try to draw a line using a piece of chalk on a blackboard , under some conditions (for example, $\alpha<\frac{\pi}{2}$ in the picture below) you will have a dashed ...
5
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2answers
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How do objects change their axis of rotation?
If I hold a pencil at its end and spin it, throwing it upwards, it will spin about its end, but will soon start spinning around its center. How is this?
I would draw the following torque diagram for ...
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0answers
49 views
Does the slinky base stay perfectly level during the initial free fall [duplicate]
In this related question:
Slinky base does not immediately fall due to gravity
It is observed that the base does not fall immediately.
Obviously the center of mass is in free fall, and the tension ...
1
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3answers
127 views
How can I solve for time without knowing the vertical velocity?
A guy posted this problem on a forum:
There is a bird sitting on a pole of height h. you throw a rock at it and the moment the rock leaves your hand the bird starts flying horizontally away from ...
1
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1answer
76 views
Pendulum in an elevator
Suppose we have a pendulum tied to the ceiling of an elevator which is at rest. The pendulum is oscillating with a time period $T$, and it has an angular amplitude, say $\beta$. Now at some time ...
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2answers
54 views
Clarification regarding Newton's Third Law of Motion and why movement is possible [duplicate]
Newton's third law states that to every action, there is an equal and opposite reaction.
If that's the case, then how do things move at all? Shouldn't all applied forces be canceled by the equal and ...
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1answer
45 views
Rotation System Dynamics - Unit conversion issues
I'm having issues with unit conversions when for rotational systems. All of my components (spring, mass, damper) come in Imperial units, so I did all my calculations in Imperial. When I convert to ...
0
votes
2answers
74 views
Will a helicoper which is hovering inside a closed box move with the box when we move it? [duplicate]
I got this micro helicopter to play with, you know that cheap double bladed ones you can find for $25 or so. Anyway last night I was on bed trying to sleep and I got this idea, what if we put the ...
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1answer
53 views
Why is there no such thing as a body in a state of acceleration?
It appears that velocity is a quantity of motion meaning that all objects can have assigned to them a particular velocity. Through the application of forces (ex: gravity, E&m) we measure changes ...
0
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1answer
39 views
Is this a correct interpretation of pressure?
So I am told that pressure = Force per Area --> F/A..
When considering the units of Force I find that force = kg * m/s^2
When considering the units of Area I find that area = m^2
Thus the units of ...
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4answers
345 views
Violation of Newton's Second Law (?)
Here the big circle denotes the circular path of a stone(small circle on path) tied to a string from the centre of the circular path .
This is COMPLETELY HORIZONTAL
At an instant the velocity in ...
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2answers
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Escape velocity to intersection of two gravitational fields
Find the minimal velocity needed for a meteorite of mass $m$ to get to
earth from the moon. Hint: the distance between the center of earth
and the center of moon is $\approx 60 R_E$, and the ...
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3answers
94 views
Man in elevator, holding it, on a scale
This is the scenario where my mass is $60 kg$, the mass of the elevator is $30kg$, and due to a malfunction, I have to hold myself and the elevator at rest. The question is, if there is a weighing ...
2
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1answer
52 views
I read a book saying bernoulli's flight equations didn't have as much impact on lift as most people think [duplicate]
I'm a computer scientist that likes to read about math and physics occasionally. A local author at a nearby aviation center brought bernoulli's flight equations into question.
It was clear enough ...
1
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2answers
67 views
How to determine a reaction force?
An object sits on an inclined plane. The weight of the object will have a normal and parallel component. I always thought that the reaction of the plane was simply the negative of the normal component ...
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0answers
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Determining the acceleration of one to another with three unknowns [closed]
Given the following image, how would you determine the acceleration of block A, and the acceleration of block B relative to A? I'm trying to include the pulley as part of block A but I cannot figure ...
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1answer
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High School Physics student needs help [closed]
A human cannon has a spring constant of 35 000 N/m. The spring can be extended up to 4.5m. How far horizontally would a 65kg clown be fired if the cannon is pointed upward at 45 degrees to the ...
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0answers
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Determining the length of a Torsional Pendulum
Currently working on this question, however I'm not sure how to solve it.
As a pendulum swings in simple harmonic motion at the surface of the Earth, the angle the pendulum makes relative to its ...
3
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1answer
71 views
Conservation of momentum in collision of two bodies
Suppose we have some ramp on wheels of mass $M$, standing on a
frictionless surface. A cart of mass $m$ moves with a certain velocity
$v$ towards the ramp. The cart moves up the ramp ...
2
votes
1answer
51 views
Oberth Effect in deep space
Does the Oberth effect only apply when in orbit of a planet or would a rocket generate more and more thrust (if kept on) even in deep space?
Wikipedia explains that the faster the rocket goes, the ...
1
vote
1answer
81 views
Gravitational potential energy of mass between two planets
Suppose I want to launch a rocket from earth to some point $O$ between the center of earth and the center of moon (on a straight line connecting their centers), where the gravitational force of the ...
3
votes
1answer
62 views
Tension of rope in the gravitational field of earth
Two balls of mass $m$ each one are connected with mass-less rope with
the same length as the radius of earth. The system is in free fall.
Prove that the tension of the rope when the nearest (to ...
2
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0answers
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What diameter is used to calculate stress in an elastomer whose cross sectional area changes continuously when streched?
Consider a cylindrical rope of rubbery elastomer with a radius (in inches) equal to the square root of the inverse of $\pi \rightarrow \sqrt \frac{1}{\pi} $ so that the cross sectional area is $1 \, ...
0
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1answer
49 views
Finding the moment of inertia through superposition?
Let's say I have a body consisting of two homogenous spheres/balls that touch each other. I also have a body fixed coordinate system which consists of that body's principal axes. I know the the moment ...
1
vote
1answer
145 views
Projectile along incline [closed]
A particle is projected with velocity $u$ from the bottom of an inclined plane whose inclination with the horizontal is $\beta$. If afterwards the projectile strikes the inclined plane perpendicular ...
6
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0answers
113 views
What determines the angle of the cushion on a pool table?
If you look at the cushions (bumpers) on a pool table, you'll see that they're not vertical. They're tilted inwards. About 10 years ago, I came across a physics exam in which one of the problems ...
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0answers
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What is the total work done in this problem? [closed]
A 1800 kg trick airplane is 450 m in the air. At this point the plane takes a dive
with an initial speed of
42 m/s and accelerates to 64 m/s, dropping
a total distance of 120 m.
(a) Using the ground ...
0
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0answers
39 views
Maximum Height of Potato [closed]
I have a bit of a problem. We made potato launchers and launched the potato's into the air. I need to find out what the maximum height my potato reached was. The givens I have are the following:
Mass ...
0
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0answers
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Understanding Kepler's $2^{nd}$ law in terms of angular momentum conservation
A) Explain how Kepler's $2^{nd}$ law - "The radius vector from the Sun to a planet sweeps out equal areas in equal time intervals" - can be understood in terms of angular momentum conservation.
I ...
