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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What is the cause of rolling friction? & why is it less than sliding friction?

Rolling friction is the resistance to motion experienced by a body when it rolls upon another. It is much less than sliding friction for same pair of bodies. When one body rolls upon another, there ...
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8 views

Dynamics question about comet approaching sun

So I have a comet of mass $m$ approaching the Sun of mass $M$ from infinity with speed $V$. If the comet were unaffected by the Sun the distance of closest approach would be $d$. I need to show that ...
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1answer
88 views

How do I describe and calculate the effect of an impacting object?

My lab studies the physiology of impact injury on biological tissues. I use a pneumatic cylinder to impart injury into a biological sample and then assess the molecular and physiological changes in ...
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0answers
17 views

Particle moving in response to central force

So I have this question: There is a particle moving in response to a central force per unit mass of $$F(r) = {\alpha\over r^2} + {\beta\over r^3}$$ where $\alpha$ and $\beta$ are constants. ...
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0answers
14 views

How to determine speed/energy of something dropped from a given height?

Say I dropped a ball from some height, which is measurable, is it possible to determine the speed of the ball when it hits the ground and thus the force exerted on the ball my the ground (or vice ...
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6answers
3k views

Why does rotation simulate gravity if motion is relative?

In Einstein's theory of relativity, if motion is truly relative, then why would somebody in a rotating space station experience (artificial) gravity? I mean, I get why they experience gravity IF the ...
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3answers
51 views

How can the bodies attain same velocities during the max. deformation during collision?

My book writes: Collision between two bodies is almost similar to the case where there is a spring between the two colliding bodies. At the instant they come into contact , the rear ball has a ...
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1answer
31 views

Finding the potential energy of a geosynchronous satellite above earth [on hold]

I am trying to find the gravitational potential energy of a 1kg geostationary satellite above the earth. So far: $E=mgh$, and $g=GM/r^2$ so substitution of $g$ into the energy equation gives: ...
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2answers
42 views

How can we show that pressure is exerted sideways too?

We can show that pressure upward and downward in a fluid is caused by weight of fluid column or volume. A simple derivation of this: ...
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1answer
51 views

Why does accounting for direction give the wrong result for a bouncing ball?

This a conservation of momentum problem, gathered from an old textbook. I thought it would be simple, but I seem to be goofing up somewhere in my basic conceptual understanding. PROBLEM: A 1.0 kg ...
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3answers
202 views

Bernoulli's principle on a curve ball

I've seen a few excellent answers here on the Magnus force, which explains why balls with a spin will curve. However, my intuition is still telling me that the Bernoulli's principle would push it the ...
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0answers
14 views

Different force vectors applied on a pulley [on hold]

All the pulleys are ideal. String is massless. Rate of work done by gravity at the given instant is (-x * 10^2) W, then calculate 'x' (refer to the diagram). By 10^2, I mean 10-squared.
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4answers
133 views

Where do Newton's Laws not work? [on hold]

I'm working on high school level project about Newton's Laws and I picked topic that describes situations, where they dont work. Can you name any practical cases where they do not work? Why do they ...
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1answer
30 views

Why is energy of emitted particles negative?

recently I had one problem here, and in comments I got interesting thing written by user Sofia. Unfortunetly, the topic is in hold now and I can't ask her more. Here is the comment: Radio-activity ...
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0answers
29 views

Will the usage of Exo-Skeleton Gear actually weaken the human body over time? [on hold]

As we all know, Exo Skeletons as they exist now are just a series of Force multiplying apparatuses working together, also the human body changes to accommodate environment specific factors in order to ...
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9answers
2k views

Physical meaning of the angular momentum

Still reading Classical Mechanics by Goldstein, I'm struggling on a very basic notion: angular momentum. I physically understand it as the momentum of an object rotating around something given a ...
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0answers
438 views

Sum of energy in a free rotation with Algodoo software

I try to understand why Algodoo software (freeware) give an efficiency greater than unity. I tested several scenes and at each time I can look the software give energy, I don't say it's all the time ...
18
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6answers
8k views

Can a car steer on a frictionless surface?

Do the front tires of a car act like gyroscopes, such that a car could steer on a frictionless surface?
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2answers
46 views

Derivation of velocities in the Coriolis force

In Fitzpatrick's Newtonian Dynamics book on the Coriolis force, he states \begin{align} v_{x'}&\simeq V_0\cos\theta-2\Omega t V_0\sin\lambda~\sin\theta \tag{433}\\ ...
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2answers
60 views

What happens to an orbiting body moving with the Earth's angular speed at various altitudes?

I was learning about inertial frames amongst other things, and I somehow came up with this question. Imagine we have a pole, made of imaginary very strong material that will never bend, placed at the ...
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1answer
31 views

Can Hooke's law go along with Newton's 3rd law & how is momentum conserved in case of spring?

Let there be a spring in its relaxed state- that is neither compressed nor extended. One end is fixed on the left and other end is free in the right. Now, I stretch the spring by pulling the free-end ...
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1answer
26 views

Falling dominoes

I have been attempting to determine the maximum velocity a line of dominoes can reach. I have found that there are two forces which act upon it: Initial impulse and gravitational force. As kinetic ...
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0answers
217 views

Why the sum of energy is not constant in this device? [closed]

The black arm is turning clockwise at $w_1$. The red disk is turning at $w_2$ with $w_2 < w_1$. The disk is turning around itself counterclockwise at $w_2'=w_2-w_1$ in the arm frame reference. ...
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3answers
68 views

Forces and acceleration on rotating objects?

Suppose you have an object undergoing uniform circular motion, with force vector pointing towards the center and another force vector tangential. Can it be said that the net force pointing in the ...
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3answers
50 views

How would filling a milk canister with helium affect the reading it makes on a scale?

Let's say that if I put a milk canister on a scale it shows 10kg. If I fill it with Helium it must necessarily be less than this, right? Can someone explain this (probably trivial) thing to me? :) ...
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2answers
81 views

Question of Conservation of Momentum

I think I understand the concept of conservation of momentum in an inelastic collision. However, what if two objects, one being more massive than the other, started out together and then separated ...
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1answer
66 views

Figuring out the time period of an Atwood system

SO I was working on Atwoods, when I came up with the following problem, It is more complicated but i should understand this simpler scenario first. As shown in the diagram above, (Atwood machine), ...
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2answers
227 views

Hourglass on the Moon

Someone asked me this, and I was surprised to find I couldn't answer it: suppose I have an hourglass / egg timer that times two minutes in Earth's gravity. If I used it on the Moon, how long would it ...
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3answers
314 views

If mass is added to a toy car does it affect its speed making it faster

If mass is added to a toy car (29.7g) and dropped down a wooden ramp would it affect its speed making it go faster? I know friction comes in to play to, so if you could give me an answer or an ...
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0answers
15 views

Postion of a cylinder rolling down an inclined plane [on hold]

I know that the acceleration of a uniform cylinder of known mass rolling down an inclined plane WITHOUT slipping with an inclination of $\theta$ is: $\frac23 g \sin\theta$. Suppose this term is called ...
2
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2answers
2k views

Slingshot Projectile motion calculation [on hold]

If I have distance the sling was dragged and the angle of the drag; then I require to calculate the projectile motion this sling shot would make. What are the equations that would enable this ...
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2answers
875 views

Elastic Collision And Momentum

The question I am working on is, "Two blocks are free to slide along the friction-less wooden track shown below. The block of mass $m_1 = 4.98~kg$ is released from the position shown, at height $h = ...
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1answer
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6answers
726 views

Why does a conservative force return the work done against it by a body to that body?

Newton's 3rd law of motion: Newton's third law of motion or the law of action and reaction implies that there is no isolated force in nature. Whenever there is any force at all , there must be ...
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1answer
40 views

Why is it that friction apparently decreases with speed? [duplicate]

Whilst thinking of a trick where a magician pulls a tablecloth directly from under a full set dinner (a classic) I wondered why friction doesn't increase as speed does. I get that they use a pretty ...
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2answers
20 views

Understanding a graph of energy conservation with bounded and unbounded motions?

This graph is from the physics undergraduate text "Classical Mechanics by Douglas Gregory". Above this graph was the statement: What I didn't understand is- as stated in the under [*paragraph], ...
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1answer
106 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 ...
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1answer
57 views

Pushing over a block [closed]

Consider a rectangular block of mass $m$ and uniform density resting on a frictionless surface. The height is $h$, the width $w$, the length $l$. Consider one of the faces with dimmensions $l$ by $h$. ...
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1answer
48 views

Big jump or small jumps?

To travel a certain distance s, is it more energy efficient to use one massive jump, or several small jumps? (First approach deleted, didn't make sense) This approach is probably a lot better. ...
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4answers
757 views

Newton's third law.. please explain here

According to Newton's third law, the force acting on object is equal and opposite to the other object that is applying the force. If I push a table with 5N force then table is doing the same. But the ...
0
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1answer
44 views

How would we find what sort of a force this one is? [closed]

The potential energy for a force field is given by $U = -Kxy$, where $K$ is a constant. The body moves in an $x$-$y$ plane. Find the force vector. $i$ is the unit vector along the $x$ axis, $j$ is ...
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2answers
96 views

Is the Fundamental Theorem of Calculus really applicable to the definition of work?

When the force $F$ on an object is not constant, then the work it performs is defined as $$W = \int_{x_0}^{x} F(X)dX.$$ Now, the Fundamental Theorem of Calculus states that $$\text{If}\,\,\, f(x) ...
1
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0answers
25 views

Weight of a hemispherical bowl and a mass $m$ [on hold]

A particle of mass $m$ is A hemispherical bowl of mass M rests on a weighing scale. The inside surface of the bowl in frictionless. A particle of mass m is released from rest at the top of the bowl ...
1
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2answers
74 views

Finding sphere of influence in multibody system

I would like to draw a boundary illustrating the sphere of influence of each body in a 3 body system. What is the best way to find such a boundary? My understanding is at the edge an SoI is the ...
5
votes
3answers
279 views

Is the Normal force dependent on the density of the object the body is resting on?

If a body is resting on the ground, the Normal force equals its weight. If I keep putting another body on top of it, eventually the body will start moving into the ground until the new Normal equals ...
0
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1answer
67 views

Can a body ever experience acceleration this strong?

Using the Schwarzschild radius formula, I approximated the Sun's Schwarzschild radius to be $3\text{ km}$. Now assuming I have a body (not a human body) which is at a distance of $10\text{ km}$ from ...
5
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5answers
431 views

Force required to drive car

From what I know of Newtonian Mechanics, if an object is moving at a constant velocity, the net force acting on that object is equal to zero. If there is friction, then the applied force required to ...
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1answer
180 views

Does a rotating plank only acquire rotational kinetic energy?

I have another doubt with a Kleppner problem :(. A thin plank of mass M and length l is pivoted at one end. The plank is released at 60$^{\circ}$ from the vertical. What is the magnitude and ...
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0answers
20 views

What are the factors involved to survive an eleven story free fall? [closed]

http://abcnews.go.com/US/wireStory/window-washer-falls-car-san-francisco-27099646 Am I the only one that thinks one could write an entire thesis on this subject?