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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When only part of the surface an object is in contact with has friction, what is the normal force I should use?

I have the following exercise: A uniform rod of mass $M$ is given a horizontal velocity $v$ on a rough track as shown in the figure. The surface is rough on the right side of the origin $O$ and ...
2
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4answers
85 views

Rotation of a vector

Is a vector necessarily changed when it is rotated through an angle? I think a vector always gets changed because its projection will change, and also its inclination with axes will always change. ...
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1answer
186 views

Kinematics equations of motion find x position in 2D from height

I have a question and I thought of 2 possible ways to answer it however the resulting answers are different which means I must be doing something wrong in my calculations. All the below happens 2 ...
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0answers
15 views

Can drag force and lift force be in the same direction in the following case?

In the attached picture, can I say that there is a lift force in the Y-direction, and a drag force too in the same Y-direction? $F_L$ proportional to V_fx$^2$ ? $F_D$ proportional to V_py$^2$ ? Is ...
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0answers
13 views

BASED ON NEWTON'S 3RD LAW [duplicate]

Q> my question is based on newton's 3rd law . An elephant pushes a rabbit with 250 N force , then the rabbit should also apply 250 N force but the rabbit is only capable to apply 25 N force . WHY ...
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0answers
11 views

How do exercise gyroscopes work?

I understand they are gyroscopes, and that they resist perpendicular rotation due to angular momentum. But why does rotating it certain ways cause it to accelerate? Also is it possible to use ocean ...
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1answer
23 views

How to calculate impulse required to move an object vertically upward by given distance [on hold]

Suppose I have a stationary object of mass $m$ and I want to apply a momentary force in the vertical direction so that it just reaches the height $h$. So how do I calculate the impulse required in ...
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2answers
43 views

Water compressibility and pressure

I am so sorry if I am missing something, but for some reason I am very confused on how water can have pressure but not be compressible. If pressure is created by individual molecules bumping into the ...
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0answers
12 views

Apply torque in 3d [duplicate]

Suppose I have an object with some inertia tensor I and angular momentum l. Suppose I apply a torque t. How does the object's orientation change over time?
3
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3answers
84 views

Is static friction the only force causing a car to move (without sliding)?

A car is moving without sliding means that the friction between wheels and the ground is static friction. This is the force causing an object to move forward, therefore, its direction is the same as ...
-1
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1answer
23 views

Net force equal to mass multiplied by acceleration of centre of mass [on hold]

$F=ma$ if $a=0$ then definitely the net force applied will be also zero (0). then, in this case $m=F/a$. If both net force and acceleration(of centre of mass) is equal to zero (0). then, isn't mass ...
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3answers
28 views

Is drag force in the direction of particle motion or opposite to motion?

Suppose water is flowing in horizontal direction (positive $x$-direction) and a particle immersed in that water is also moving in the same direction. In this case, is the drag force $F_D$ in the ...
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3answers
39 views

Does angular momentum of a system whose Moment of Inertia is changing remains constant?

In this problem, the moment of inertia of system is increasing. Correct option given is (b) and it is argued that no external torque acts. But If moment of inertia is changing , there should be a ...
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0answers
32 views

Is there anything wrong in this document? [on hold]

https://www.mediafire.com/?m39l0t6bwd29241 Although the last line is not finish thou, I am confused about the Gas laws and how it may affect the volume of the gas inside the balloon
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3answers
302 views

Finding the acceleration of a mass/pulley system without knowing the direction of the displacement

I have the following question: I noticed that if I solve for the acceleration assuming that the acceleration is occuring to the left, I get the equation: $\displaystyle a = ...
0
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0answers
48 views

Finding $\theta$ at any point in time [duplicate]

I am looking to simulate the movement of a steel beam which has a constant mass $m$, and that has a pivot $O$ at one end that is moving with a constant horizontal velocity with magnitude $v$. ...
1
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2answers
229 views

Why do particles of equal mass (with one at rest) undergoing elastic collisions scatter at only right angles?

This is from the Section 9.6, page 351 of "Classical Dynamics of Particles and Systems" by Thornton and Marion. By setting a up a system where mass 1 has initial momentum $m_1 u_1$ and mass 2 is at ...
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0answers
14 views

Momentum conservation problem, elastic collision [duplicate]

This question has got me thinking for a while now and I haven't been able to come up with any answer at all. I've done the basic conservation of momentum, kinetic energy but I have no idea how to ...
0
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2answers
214 views

Does rotation cause gravity? [on hold]

I want to ask that what causes gravity. My opinion is that it is the rotation that causes gravity, when we see a whirlpool in water it takes anything that comes near to it in to the center of it. I ...
2
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4answers
172 views

Why does Torque exist?

Specifically, why does force increase with the moment arm? What about making a perpendicular force farther away from the axis of rotation increases it? How does the moment arm cause that?
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0answers
13 views

Classical space-time and quantum indiscernibility [on hold]

Non-relativistic QM works in Newtonian space-time. Does the representation of a quantum system in this setting individualizes it in such a way that this conflicts with the non-individuality and the ...
1
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1answer
41 views

How to explain gyroscopic precession in a more intuitional way?

When Studying the phenomenon of precession a classic example installation is this: a wheel spins around the Y axis, gravity applies and the upper part starts spinning around the Z axis. The textbook ...
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1answer
158 views

Natural frequencies of a torsion system

Find the angular displacement $\theta_1(t)$ and $\theta_2(t)$ of the system shown in figure below for the initial conditions $\theta_1(0)$, $\theta_2(0)$, and $\dot{\theta}_1(0) = \dot{\theta}_2(0) ...
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0answers
36 views

Why is this wrong? [on hold]

All surfaces are frictionless. My aim here is to relate the two accelerations. Why is $a_1\sin\theta = a_2$ i.e the horizontal component of $a_1 = a_2$ wrong? I know that the correct answer is $a_1 ...
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3answers
33 views

Components of gravity in an inclined plane

The reason the block accelerates down the inclined plane is that the resultant of $N$ and $mg$ acts down the incline. However, why is the force causing the block to accelerate down the incline often ...
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2answers
538 views

Projectile Motion

I know the angle at which a projectile is launched, how far it needs to go, and also the maximum height. How can I find the initial velocity needed (disregarding air resistance)? Currently, I am ...
3
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2answers
34 views

Creasing of a material at the molecular level

What exactly happens when a material (particularly paper or even cloth or a metal) is folded to form a crease? Why is it that a creased material tends to retain form, while a lightly folded one, ...
-4
votes
1answer
53 views

Based on newtons third law [on hold]

If an elephant can apply 250N force and a rabbit can apply 25N force , and if they are pulling each other , then elephant will pull with 250N force and according to newtons third law the rabbit should ...
1
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0answers
11 views

Net force of a falling down people by Resolution of Force. [on hold]

From the picture, I want to calculate the Force (F) when people fall down. I searched the internet, but I have no findings. Given that Mass (M) = 75 kg, Gravitational force (G) = 9.81 N. How can I ...
3
votes
1answer
304 views

Fluid dynamics tsunami

I have been given a energy head (pressure) in meters for a given tsunami on land. If the tsunami hits a wall 1 meter by 1 meter, is it possible to calculate the height it will reach. I am thinking it ...
0
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1answer
24 views

Moment of inertia and gravity

Would the objects have moment of Inertia if there was no gravity? Because imagine a bar, if I put my hand at the center of the bar and rotate it, it would be easier than rotate the bar picking one ...
1
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2answers
219 views

Confusion about gravity

I understand the “rubber sheet” model of Relativistic gravity is just an illustration, and beyond the initial issues of mixing three dimensional objects with a two dimensional representation of 3D ...
5
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3answers
599 views

Thrust center in space

I have this dilemma: Suppose you have a space ship somewhere in deep space, where there is no drag force or substantial gravity. If the ship has a single engine situated in such a way that the center ...
0
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1answer
21 views

Working with the problems related to potential energy

Consider a spring mass system. A block is attached to a light vertical spring which is stretched under the load of block and this system is at a height $h$ from the ground. Now my problem is ...
2
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2answers
43 views

How do we determine if a certain physical quantity is a vector?

For instance in Newtonian physics we treat position of objects, displacements, velocities, forces, momenta, angular velocities etc all as vector quantities (little arrows in space which have a certain ...
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1answer
31 views

Conservation of Angular Momentum for an Object Not Rotating

I have a point mass connected to a string with negligible mass. The point mass has mass $m$ and is moving at a velocity $V$. The string is of length $r$, and it is keeping the point mass tied to a ...
-1
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1answer
55 views

Circular motion and inclined friction [on hold]

I'm given the following picture: A car with the mass m passes the top of a hill with the height H. The coefficient of friction is $µ$. The speed of the car is $v_0$ in the moment of braking. ...
4
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3answers
72 views

How do I find the relation between the accelerations of the ring and the disc (see image)? [on hold]

What is the relation between the accelerations of the ring and the disc (see image)? Both the ring and the disc have mass $M$. The ring has a radius $R$ and disc has radius $2R$. They are connected ...
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0answers
31 views

Torque, need help understanding a solution [on hold]

https://www.scribd.com/doc/100022472/Monbukagakusho-Physics-2010-Solution Problem B. This guy's answer just doesn't make any sense at all to me but he did arrive somehow at the correct solution. If ...
0
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3answers
62 views

Rolling dynamics of round objects down an incline

If a cylinder is rolling down an inclined plane with inclination $\theta=30^\circ$ (with coefficient of static friction between cylinder and the plane $\mu_s=0.8$) without slipping and it has mass ...
2
votes
1answer
45 views

Does deformation due to a force affect the acceleration produced by it? [closed]

You have two same masses, one non-deformable and the other plastically deformable. You exert the same force for same time. Will they move with the same speed? Obviously the one will deform and move, ...
1
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2answers
176 views

Computing Acceleration in mass and pulley system using conservation of energy

I have a question in which a multiple pulley and mass system is being analysed. I can compute accelerations and Tension without any issue using newtons second law. However I am asked to use ...
0
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0answers
22 views

What are the calculations specifically needed for High Altitude Ballooning? [on hold]

I want to know the lifting gas needed to launch the vehicle including the positive lift I want to predict the possible retrieval site I want to know the burst altitude AND MAYBE ALL WITHOUT ...
3
votes
2answers
364 views

Projectile motion maximum distance to origin

Is there an elegant or easy way to derive the maximum distance from the origin to a point of the parabola created by projectile motion (assume initial position is the origin)? Other than ...
1
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1answer
41 views

Free fall in non-uniform field

Imagine I'm a space-diver, with mass $m_1 $, 500 miles above the Earth's surface at $x_i$. I want to calculate my position, velocity, and acceleration as a function of time, accounting for the Earth's ...
0
votes
2answers
51 views

Why an impact exerts so much force? [on hold]

If an object of velocity $v$ and mass $m$ moves towards a resting object of mass $M$, then if the object which is hit might break. Why? What is the reason that a collision has more power than a ...
0
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2answers
171 views

Coriolis force in free fall: Directions?

Inspired by this Phys.SE question, Coriolis force in free fall, I have to ask: Why does the Coriolis force act in the east-direction? I would say, if I jump from a high distance and look at the ...
4
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3answers
155 views

Velocity in a turning reference frame

I often see the relation that $\vec v=\vec v_0+ \vec \omega \times \vec r$ in a turning reference frame, but where does it actually come from and how do I arrive at the acceleration being $$\vec ...
0
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4answers
71 views

Action is equal to reaction. Then how is a horse able to pull a cart? [duplicate]

Please answer the question in detail. I have tried other websites for answers but was not able to understand properly.