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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Why an impact exerts so much force?

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 ...
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2answers
161 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 ...
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3answers
25 views

Circular motion and inclined friction

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
147 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 ...
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4answers
66 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.
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2answers
177 views

Find the force needed to accelerate body to a certain velocity for a certain time with respect to drag force

So, the problem is straightworward when we suggest that air resistance force is constant: $$ \vec F = \frac {\vec V_1 - \vec V_0} {t} m / b $$ $$ \vec V_0, \vec V_1 - \text {initial and final ...
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1answer
22 views

100 lbs of drag? Really? Chain running physics

Recently came across this video of an endurance technique involving the strapping of a 100lb chain to one's back and running along the grass dragging it behind. What is the true force experienced by ...
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2answers
29 views

How do I use a free body diagram in this case?

In the above cases I want to find the acceleration $a$ for $m_1$. I can do it by considering $m_1$ and $m_2$ to be a system, which would give me $a = F/(m_1+m_2)$. How can I use a free-body diagram ...
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2answers
817 views

Defy gravity torques with gyroscopes?

Context On the following drawing, a platform is hung from the ceiling not exactly from its centre of gravity. Because of this it can't sustain an arbitrary orientation for long; I want to increase ...
5
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4answers
791 views

Why is Newton's first law necessary?

Newton's second law says $F=ma$. Now if we put $F=0$ we get $a=0$ which is Newton's first law. So why do we need Newton's first law ? Before asking I did some searching and I got this: Newtons first ...
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0answers
29 views

Is 12-6 Lennard-Jones potential smooth confining potential?

It's obvious that 12-6 LJ is a 2-body potential. The potential $V$ is said to be a confining potential $V(\pmb{q}) \to \infty$ whenever $\pmb{q}_i \to \infty$ or $||\pmb{q}_i - \pmb{q}_j|| \to ...
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1answer
17 views

Normal Contact Force of Acting on Two Posts [on hold]

$\textbf{Question A.}$ A goal frame has a mass $100\,\textrm{kg}$, and has two identical posts $p_1$ and $p_2$ and a uniform crossbar. Respective contact forces $r_1$ and $r_2$ act vertically on the ...
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0answers
31 views

What is $T_1$ and what is $T_2$ in Capstan law?

How do I determine which force is which (T1 or T2) in the Capstan law? In case there is no rotation and in case there is rotation of the capstan.
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2answers
615 views

Loads in decelerating a falling object

I remove trees in confined spaces setting up rigging systems, I am keen to look at the science behind it in more depth so far the formulas that I have found don't take into effect the ongoing effect ...
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1answer
24 views

Why is the first part of equation i.e $v_0(t_f-t_0)$ not considered while plugging real life problem to it?

Why is the speed*time stuff is not present while we look for the distance? I got it from this (physics for dummies)
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3answers
75 views

What is the physical meaning of reduced mass?

If we stick two block masses by a string and pass it over a pully and let the blocks free then mathematically we can obtain that the whole weight on the pully is more if the blocks are kept at rest, ...
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3answers
2k views

Throwing a ball upwards in an accelerating train

If I throw a ball upwards to a certain height in an accelerating train, will it end up in my hand? At the moment I release the ball, it will have a velocity equal to that of the train at that instant. ...
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0answers
41 views

Plucking Guitar Strings

I was given this prompt: A musician frets a guitar string of length 1.5 m at x = 0.28 m with one finger, and simultaneously plucks the string at x = 0.14 m with another finger (raising it to a height ...
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2answers
32 views

Why is the centripetal force vector on a banked turn horizontal rather than parallel to the incline?

Why isn't the centripetal force parallel to the inclined surface? It seems like if you were to draw a circle with one point being at the center of the curve and one point at the car the circle would ...
-1
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1answer
53 views

Calculating kinetic energy without Mass [on hold]

Is it possible to calculate the kinetic energy of a body if its velocity is given its direction is vertical and its hight is 0 at moment t=0
1
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3answers
417 views

Trajectory of rolling billiard ball after collision with another billiard ball with same mass

So, according to this article http://www.real-world-physics-problems.com/physics-of-billiards.html , the trajectory of white (cue) ball is always perpendicular to the line connecting center of ball ...
3
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0answers
36 views

Dynamics of pairwise distances in the $n$-body problem

Consider the $n$-body problem where we are interested in describing the time evolution of $n$ masses interacting through a potential $U$. Let $D$ be the matrix containing all pairwise distances ...
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3answers
65 views

Experiment proving that the Earth is rotating around the Sun [duplicate]

Is there any simple experiment done on Earth proving that the Earth is rotating around the Sun? Something in the same spirit of what Foucault did proving that the Earth is rotating around itself. ...
3
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3answers
159 views

Center of mass motion and variation of mass

Here are the proofs regarding the center of mass motion as reported on my book. $$\vec{r_{cm}}=\frac{\sum\vec{r_i} m_i}{\sum m_i}$$ $$\vec{v_{cm}}=\frac{d{\vec{r_{cm}}}}{dt}=\frac{1}{M}\sum ...
3
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1answer
5k views

Add air resistance to projectile motion

I am given an initial x and y position and initial velocity and I was asked to graph the trajectory in 1 second intervals. This is what I have so far: If $x_0 = 1, v_{0x} = 70, y_0 = 0, v_{0y} = 80, ...
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0answers
71 views

Euler's equations (rotating frames)

I'm trying to understand the Euler's equations and I'm having problems with rotating frames and on which specific frame is each quantity measured. On the equation $$ ...
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2answers
67 views

How can gravity have a horizontal component?

$mg$ obviously has no horizontal component, but on resolving it into components it seems to have a horizontal component $mgcos\theta sin\theta$. I know I'm doing something wrong here. How is this ...
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2answers
75 views

Centripetal force: if radius decreases, does ANGULAR or TANGENTIAL velocity change?

Having conceptual trouble with this aspect of centripetal force. Say we have a puck on a frictionless table attached to a string that I am holding through a small hole, so that the puck moves in a ...
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1answer
40 views

Angular momentum definition? [on hold]

The definition of linear momentum is this: Momentum is a vector quantity defined as the product of an object's mass, $m$, and its velocity, $\vec v$. So According to that definition,The definition ...
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1answer
26 views

How does an object with gravitational energy exhaust that energy as work?

To my understanding (which is pretty basic) energy is the ability to do work. The higher objects are above a point - more gravitational energy they have relatively to that point, which means that they ...
2
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0answers
23 views

What is happening to energy that is not used as work? [duplicate]

To my understanding (which is pretty basic), energy is the ability to do work. But if for example, I push a wall, I do exhaust my energy, but no work is done since the wall is not moving. So what is ...
1
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1answer
67 views

How to calculate torque required? [on hold]

Here's my problem diagram: I am working on a hobby project in which a motor is required to rotate a pulley that is connected to a pendulum as shown in the image. The maximum torque, Horsepower and ...
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0answers
17 views

Find force using mass, $x$ and $y$ coordinate [on hold]

Body with a 3.00 m move along the x,y cordinate.x=5t(2)-1, y=3t(3)+2, t=2.00 How to find force F? I tried to solve problem using newton`s second law
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1answer
54 views

What is $\omega \times v$?

I found that equation in my textbook. It says that $\omega \times v$ ($v$ is velocity) is centripetal acceleration. But how is the equation derived?
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3answers
124 views

Does the work done by a person equal the work done on the object in this situation?

If you applied a constant force over a floor that has friction on an object, would the work done by the person equal to the work done on the object? Assume that the floor is flat and that the object ...
0
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2answers
44 views

How does kinetic energy do work?

To my understanding, work is done on object A when object B is applying a force on object A, causing object A to displace. Since energy is the ability to do work, what work does a moving object do, ...
0
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1answer
18 views

Accelerating Hard in an EV More Wasteful?

Is accelerating hard in an electric (or any, for that matter) vehicle any more wasteful than accelerating slowly? My flimsy grasp of physics suggests that it shouldn't be. The energy required to ...
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2answers
44 views

How can an accelerating inclined plane prevent a block on it from sliding?

If I increase the force $F$, only the normal force $N1$ acting on $m1$ would increase which has no component along the plane, ie. along $m1gsin\theta$, so how would applying this force prevent m1 ...
0
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0answers
19 views

Do all objects free fall at the same rate regardless of their mass? [duplicate]

Is it true that all object will fall at the same speed in vacuum irrespective of their mass because the acceleration due to gravity of Earth is 9.8 m/s2. Then what happens to the gravitational force ...
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0answers
49 views

Inverted pendulum with reaction wheel

I'm a little confused about the equations of motion of the reaction wheel pendulum. It is used in self balancing bicycles - see vide link in comments (I can't add another link here due to low rep). Or ...
1
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0answers
30 views

If gravity on a non-rotating body suddenly stopped, would an object on the surface fly away? [on hold]

This is a very trivial question, and I tried to word the title as concisely as possible, but I can't seem to figure it out. This is not referring to any hypothetical discussions regarding Earth. ...
3
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2answers
189 views

Mass-Energy Equivalency

We call $E=mc^2$ the Mass-Energy Equivalency because it equates mass and energy together. But, by that same logic, shouldn't we call $E=\frac{1}{2}(mv^2)$, the equation of kinetic energy in Newtonian ...
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0answers
65 views

Moment of Inertia of a thin rod in the shape of a triangle question? [on hold]

Question: Find the moment of inertia of a uniform thin wire in the shape of equilateral triangle of mass $M$ and side length $a$ about the polar axis through the centre of the triangle. So I took ...
1
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2answers
393 views

Correct terminology for combined kinematic and dynamic state

The kinematic state is defined as the position and orientation in space. The dynamic state is defined as the associated velocities. What is the correct terminology for the combined kinematic and ...
1
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0answers
61 views

Ball Rotating in Place Under Waterfall

https://www.youtube.com/watch?v=Khf6koh3IO8 Can anyone help me explain this? It seems like the ball should shoot out from underneath. I have two main theories. 1) Bernoulli's Principle says that the ...
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2answers
40 views

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 ...
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1answer
36 views

Deriving an equation for a projectile launched on a ramp using two springs

I had a physics lab where I had to build a sling shot sort of devices on a ramp. Basically, I have a ramp, with two springs attached on the end and the two strings are attached to a piece of wood. I ...
0
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2answers
98 views

Rotational Torque Versus Thrust on a Screw

We all used screws and tightening them before, but here is my question. If a Thrust-like load behind the other side of the screw can move the screw out (example pushing), then how much force is it ...
0
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2answers
38 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 ...
1
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1answer
276 views

Rotating platform with pulleys and stacked blocks

This was a practice test question. Consider the following figure. (If the frictional coefficients are unclear, between A and B we have $k_1 = 0.3$, B and platform is $k_2 = 0.2$. If you further ...