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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Can a DIY balloon become a danger to others?

A couple of years ago I remember reading that a DIY group sent a $25 balloon 20km into the air. This made me think for a while because if they lift about 5Kg that high It would generate more or less ...
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99 views

How was this formula in my textbook was derived?

How is this formula derived (it is present in one of the hundred pages of my textbook about physics and fundamental physics) In the case of a system of particles $P_i$, $i = 1, …, n$, each with mass ...
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223 views

Making a cut trough a center of mass, can the masses of the pieces be equal?

Let's say point $P$ is the center of mass of an irregularly shaped object. If I make a straight cut trough point $P$ and split the object in two, is it possible for the two pieces to have the same ...
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184 views

Stretching a rod? [closed]

The stress applied on a rod is linearly proportional to its strain. But shouldn't the opposite be true? I mean if you pull particles further apart doesn't the force they apply on each other decrease ...
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298 views

Will an object resting on a rotating platform move in a frictionless world?

Imagine that a pebble is placed on a uniformly rotating, frictionless disk. What will happen to this pebble? Will the disk slide under it and the pebble stay as is? Or will there be a centrifugal ...
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110 views

In Newtonian pressure, what type of function is force?

This is pressure in Newtonian mechanics: $$P=\frac {dF}{dA}.$$ What does this mean? (Doesn't it mean that force is a function of area?) What type of function is force?
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203 views

Violation of Newton's 3rd law

I'm just expressing my guess. Let two particles A and B experiences forces $F_1$ and -$F_2$ between them and let guess also there are two observer, one is stationary and other is moving with ...
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3k views

Force with zero acceleration [duplicate]

If I apply a force on a body which is kept against a wall, then the body will not move. The body is not moving means that its velocity is zero, and hence its acceleration is also zero. According to ...
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1k views

What happens if object is thrown in empty space?

If I throw a object in empty space, I apply a force to throw that. Then it gains some acceleration and it's speed increases. So will it's speed keep on increasing, or it will get stable? If yes, ...
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61 views

How do I know the position of some mass in space (starting at rest) over time when applying earth's gravitational force to it?

I know how to use Newton's law of universal gravitation. But I'm not sure where to go from there. This is for my understanding while working on a game. I'm not trying to do anything fancy here.
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12k views

Work done by spring over distance

I'm working through a problem involving energy conservation. Unfortunately, I cannot calculate the work done by a spring. ...
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3k views

How do I find the tension in additional strings in this problem? [closed]

A mass of 5.00 kg hangs attached to three strings as shown in the figure (see image below). Find the tension in each string. Hint: Consider the equilibrium of the point where the strings join. ...
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Who is right? Force exerted on a body. Me or my friend?

Three masses $m_1 = 3\text{ kg}$, $m_2 = 9\text{ kg}$ and $m_3 = 6\text{ kg}$ hang from three identical springs in a motionless elevator. The elevator is moving downward with a velocity of $v = ...
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50 views

Movement of accelerating points with maximum speed (i.e. running away from tiger) [on hold]

I'm walking through a forest and suddenly I see a tiger. And now I have a problem. I want to know how much time I have left but I don't know how to calculate it. Or more formally: Let's ...
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114 views

Why do termite pellets fall in a perfect circle?

I was just wondering why termite pellets fall down from my bed in a perfect circle. You can see from the images that the follow down on the floor making a perfect geometric figure which is void in ...
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82 views

How is the uniform gravitational field approximation $F_g\approx mg$ near Earth's surface derived from Newton's law $F_g=GMm/r^2$ of gravitation?

I am really bothered about how we can derive the equation of projectile motion. Suppose a point mass will move in the gravitational field of the Earth according to the equation $$\ddot R ...
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48 views

Speed needed to make a car jump from a ramp

(I've posted this question on GameDev and I've been told to ask here so I'm pasting the question) I need to make a car jump from a ramp to another, and I need this to be done using AI so I thought it ...
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53 views

In circular motion, what's preventing me from calculating the circumference of the circle, dividing it by time to find the speed of the object?

There are equations to solve for the speed in circular motion. However, is there anything preventing me from calculating the circumference from the given radius, and then divide that over the time to ...
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63 views

Tension on a string

A string is attached at both extremities and put under tension $T_0$ at rest. We know that if we pull the string upwards from the middle, the tension will increase. But why is it that, admittedly, ...
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48 views

Since Earth spins, would an aircraft travelling opposite to direction of Earth spin take less time? [duplicate]

Suppose we want to reach the point on earth which in relative terms is exactly on the opposite end of the sphere we call earth (I know it is not an exact sphere). We either dig vertically downwards, ...
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66 views

Why oobleck does not obey Newtonian dynamics? [duplicate]

In the following post we can see that some guys are walking on Non-Newtonian fluids. As far as I know that, we can not predict the exact amount of strain if we predict some forces. therefore the curve ...
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77 views

About Kepler's Law

When Earth goes near the Sun, its velocity increases and when it goes far from the Sun its velocity decreases. Then why according to Kepler's law is the time period $T^2 \propto a^3$, where $a$ is the ...
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192 views

What are absolute space & time? Why are they not absolute in reality?

As said by A.P. French in Newtonian point of view: Space is a sort of stationary three-dimensional matrix into which one can place objects or through which objects can move without producing any ...
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179 views

Do objects really move in the direction of the force applied?

According to the second law of motion: Direction of the force is in the direction of change in momentum. Now, I came before a problem. Though an easy one, I was perplexed at a point. A ...
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134 views

What is this simple mechanism called? [closed]

I often build with Lego and use this mechanism: It converts the rotational movement to linear by making the stick between the two blocks go back and forth. What is this mechanism called?
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243 views

Why do you have less control over a bicycle with a broader steer?

I recently had an argument with someone on why a bicycle with a broader steer gives you more control. We both had different answers to this question and neither could convince the other. First a ...
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213 views

If Earth starts moving when attracted by an object, where does the energy come from?

Suppose a body(very big but not bigger than Earth) moves against gravitational force of Earth. The force will do negative work on the body decreasing its kinetic energy. The decreasing energy is ...
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5answers
164 views

Relation between the conservation of Energy and the conservation of Momentum?

I just learn about the momentum and it conservative attribute in a closed and isolate system and there is something I don't understand when I relate it to the conservation of the energy Considering ...
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281 views

Space Elevator: how would you keep the end of a Space Elevator's cable rigid?

I had a discussion with my wife about physics behind a Space Elevator. Imagine a cable rising 60k into the firmament for its elevator to climb. The cable would have to rotate in unison with the earth, ...
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98 views

At what altitude above equator do gravitational and centrifugal forces cancel each other? [closed]

How high has to be a tower at equator to get on its peak the same - but of course inverted sing - value of gravitational and centrifugal forces?
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119 views

Distinction between torque and force

Distinction between Torque and Force. Consider a case when a cylinder is rolling down a rough inclined plane. While analysing its motion, we consider the force applied by the friction and the ...
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261 views

equivalent spring constant for a drum floating in water

If I have a drum floating in water, how do I find the equivalent spring constant? I know that the water has density $\rho$, the drum has diameter $d$ and height $\ell$, and the positive direction is ...
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5answers
534 views

Who does work while walking?

While walking the work done by friction is zero. But who does the work, actually? How someone is getting displaced? This situation also arises when someone climbs without slipping or is climbing a ...
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62 views

Will this achieve linear movement of a closed container?

Can I create a device that moves in one direction with a design like Figure 1? I suspect that the forces cancel each other by the recirculation. It is a simple exercise of action and reaction, but I ...
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140 views

Olympic weight lifting bar, plate location affect

I apologize in advance for the rudimentary nature of my question. A perfectly balanced weight lifting bar is loaded with three weight plates on each side. The three plates are 25kg, 10kg and 5kg. ...
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237 views

Newton's third law, action vs reaction

When I push a wall with my hand, the wall does the same and because both forces cancel out the sum of the forces applied by me on the wall and the wall on me is zero, plus the friction on the ground ...
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2answers
4k views

Loop-the-loop question [closed]

Problem: The marble rolls down the track and around a loop-the-loop of radius R. The marble has mass $m$ and radius $r$. What minimum height $h$ must the track have for the marble to make it around ...
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122 views

Newton's third law of motion when moving between two surfaces

If for every action there is an equal but opposite reaction, then why doesn't a ball keep on moving when made to move between two surfaces, should elasticity of surface, gravity and friction be ...
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92 views

Ice throw from industrial wind turbine

I was watching a documentary where the residents didn't want to have a wind turbine erected nearby. One of the comments from the company was that an ice throw would have very little importance since ...
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1answer
216 views

How to obtain the distance traversed by a free falling body equation?

I know that the distance that a free falling body has traverse through time is given by $d=0.5*g*t^2$. I would like to know how to get to this equation to study a bit more how it was obtained. I have ...
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1answer
220 views

Is there such a thing as instantly stopping?

I'm sorry if this is a stupid question, but I've never taken a physics class and I was curious about something. But anyway, my question is, is there such a thing as instantly stopping? For example, if ...
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2answers
165 views

How to find time, acceleration under this situation

I am trying to solve the following. An object of mass $m$ slides on a horizontal surface with initial velocity $v_0$. If the kinetic friction between the object and mass is given by $\mu$, find ...
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3answers
7k views

Constant Velocity 'Force'?

According to Newtons second law: F = ma, if acceleration is zero then the force must be zero, but assuming you have an object moving with a constant velocity of say 2 m/s, and that object strikes you, ...
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1answer
217 views

Ball on a slope [closed]

I have a lab report, but I can not write it in a correct way. The lab experiment was about a ball rolling on a slope, I have a height of the slope, the distance, and the time in which the ball spent ...
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2answers
990 views

Acceleration of pendulum

At what point of a pendulum's swing is its acceleration the greatest? What does this tell you about where the forces act in a pendulum? Is my answer correct? The force that causes the acceleration ...
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1answer
52 views

characterization of potential

So i have a force field $F(x,y)$ and i have to find out wether it is a potential or not. My first idea was to calculate : $dU=Fdr$ (where $r$ is the radius vector) , to integrate on both sides and ...
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1answer
117 views

Time taken for collision [closed]

We have three particles at the vertices of equilateral triangle of side $d$. At $t=0$ they start moving in such away that at all instant of time each of them has a speed $v$ towards adjacent one. We ...
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4answers
994 views

How can acceleration $a$ be zero when applied force $F$ is non-zero?

An object is at rest and stays at rest, but an attached rope pulls with increasing force. What is the acceleration? The correct solution is that acceleration is constant and 0. Obviously $a= dv/dt ...
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1answer
127 views

Earth's rotation isn't that orbit?

If the earth is rotating at some $465~\text{m}/\text{s}$ at the equator and that's really fast. Shouldn't we in that case be in orbit with the earth just not fast enough? How fast do we need to ...
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259 views

Kinetic energy with no velocity

When a body is displaced against the gravitational field of force it gains potential energy. When we drop the body it begins to move downward with a certain amount of acceleration, and the potential ...