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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General construction of equations of motion for free particles

I've got a question regarding the different Symmetrie-Lie-Groups of Newtonian Mechanics and special realtivity. Is there a canonical way to obtain the equations of motion for a free particle only by ...
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3answers
32 views

Distance traveled by a water jet

I helped my kid in a science fair project, where we punctured holes in a water bottle at various heights and then measured the distance traveled by the water jets before they hit the ground. The ...
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24 views

Free body driagram of box and plate with a friction force on a smooth surface

On a smooth surface we have a plate of 40 kg and on that plate a a box of 10 kg. Between the plate and the box there is a ...
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1answer
31 views

Newton's law for rigid bodies

Is newton's third law valid for rigid bodies? Say, if we have a bullet hit on a rod which is vertically placed on a rough floor. Friction is just sufficient sp that the rod rotates and does not ...
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2answers
24 views

Resulting force when bending plywood

My sister and I are working on a thesis in interior design on a plywood chair similar to the picture, where the red part bends. We are trying to work out how much the plywood would push back when a ...
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1answer
25 views

Determine normal forces on tilted table [on hold]

A table with the mass m, the height a and the width b is resting on a tilted floor with the angle of rake $\alpha$. A block at A prevents the table from sliding. Determine the normal forces from the ...
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2answers
35 views

Work done by frictional force on a sliding block

A block slides across a table horizontally with an initial velocity $V$. The frictional force $F$ brings it to rest after its Centre of Mass covers distance $S$. What is the work done by the ...
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1answer
35 views

Free-Falling Object

How does the presence of air affect the rate at which a body falls? What is the rule for falling objects, when there is little or no air resistance?
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28 views

Calculating the 3-dimensional torque on a non-uniform rigidbody given the angular acceleration about its center of mass

Say I have a rigidbody, made up of several point particles with known masses and positions relative to the center of mass. How would I find the torque on this rigidbody given its angular acceleration ...
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0answers
22 views

Help with inclined slope motion? [on hold]

I have this question (5ii) and I was wondering why this wouldn't work, why can't I solve for acceleration using $v^{2}-u^{2}/2s$=$a$ then solve for $t$? I obviously have to resolve and use $p=fv$ but ...
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1answer
75 views

When will the pringles can fall?

When I'm pushing a tall, cylindrical object stood on its end (like a Pringles can) I can push it near its bottom, and it will slide forwards, or push it near the top, and it will topple over. So, ...
3
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1answer
34 views

Why is energy in a system typically able to be described using quadratic expressions?

This might be more of an applied math question. Why is the energy of a system typically able to be described using quadratic expressions. Is there an underlying mechanic that drives this?
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6answers
1k views

Can you ever exert more downwards force than your weight?

So, because I'm a hardcore person, I risked all this afternoon by going out in the wind, the rain and the cold to construct a willow den. Yes, it seems a menial task, but it was actually quite ...
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1answer
25 views

Average force for repeated elastic collisions

I was asked to compute the average force exerted by a rigid spherical ball (mass m) on the floor over infinite time, in a situation where the ball is dropped vertically from a height (h) and makes ...
2
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0answers
22 views

Distribution forces

I've got two trees and between them is a rope. When someone about 100kg sits at the center of the rope, what are the forces on both parts of rope (to the left-hand side from the person and right-hand ...
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0answers
22 views

Does relativity in any way “disprove” Newton? [duplicate]

I was reading a science magazine and it claimed that Einstein's theory of relativity disproves all of Newtonian physics. I was highly skeptical because all we have been learning at school is Newtonian ...
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0answers
16 views

frequencies that affect newtonian and non newtonian liquids [on hold]

I have a science fair coming up and i need to know which sound frequences affect liquids, both newtonian and non newtownian. i also need to know the science and formulae behind it. Your answers will ...
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1answer
33 views

Working out length of taut rope orbiting the earth remaining straight and radially directed [on hold]

A taut rope is orbiting the earth with angular velocity $a$. It remains straight and radially directed. If the midpoint is located at radius $r$, find the length of the rope. I can't even imagine ...
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3answers
70 views

On a scale, why does the heavier object go down?

When you balance a pencil on your finger, I have always wondered, "Why does the heavier part go down, and the lighter, up?"
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1answer
24 views

Does mass distribution/center of mass affect free fall?

An everyday is example would be cars. If you were to drop a car, not taking air resistance into account, would a front-heavy car tumble forward as it fell? And a car with a perfect 50/50 front/rear ...
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4answers
823 views

Paradox in applying Newton's second law [duplicate]

Suppose I apply two vertical but opposite forces with the same magnitude in a body like is shown in the picture: According to newton's second law, the center of mass shouldn't accelerate, since the ...
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1answer
28 views

Parabolic slide [on hold]

Can you give a big hint for this problem please? A material point is released at the end of a track in the form of a vertical arc of parabola $y = x^2$ in $[-1,1]$, the meter is selected as a unit ...
1
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1answer
43 views

Circular motion from rest [on hold]

A particle $P$ is suspended from a fixed point $O$ by a light string of length $a$. When hanging at rest under gravity at $A$ it is given a horizontal velocity $u$. The particle moves freely in a ...
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3answers
61 views

Work-Energy conservation with friction

I didn't go to the lesson of work-energy theorem, so I miss something about this subject. I know the formulas, but I can't figure it out. This question has many quantities. Here is the problem, ...
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1answer
41 views

A moving brush on a vibrating surface

Hi group, I am a HS student in China preparing for a regional Young Physicist Tournament even. We are very puzzled about why would there be such movement. We would be grateful to see any inspiring ...
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1answer
24 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 ...
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0answers
48 views

Center of Mass of Snowman [on hold]

Suppose you build a snowman 6 feet tall by stacking 3 spheres. The bottom sphere has a diameter of 3, the middle one a diameter of 2, and the head a diameter of 1. What is the center of mass?
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1answer
30 views

What is the position as a function of time for a mass falling down a cycloid curve?

In the brachistochrone problem and in the tautochrone problem it is easy to see that a cycloid is the curve that satisfies both problems. If we consider $x$ the horizontal axis and $y$ the vertical ...
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1answer
62 views

What makes the equations of motion dependent on each other?

When Galileo put forward the proposition that the motion of a projectile analyzed into separate horizontal & vertical parts, he made a great contribution to the conceptual basis of mechanics. ...
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1answer
34 views

Free fall actual motion direction on the rotating earth [on hold]

I've calculated that the actual acceleration that a body experiments taking into account the gravitatiotional atraction of the earth and the centrifugal pseudo-force is given by: ...
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1answer
21 views

Deriving the equation for the speed of a block down an incline using work - keep getting the wrong constant

So the question is: There is a block of mass $m$ travelling along an incline that makes an angle $\theta$ with the horizontal. If the block is pushed up the incline with an initial velocity $v_o$, ...
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1answer
49 views

Finding the equation of motion

I am currently working on a problem where a particle of mass $m$ can move along the x-axis with no friction. The particle is moving in a gravitational field and the potential energy is given by: ...
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2answers
54 views

Why doesn't a magnet on a refrigerator slide down?

Obviously gravity pulls objects towards the earth's surface. Now suppose I have a refrigerator and a magnet. The magnetic force is perpendicular to the gravitational force. So it is not counteracting ...
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1answer
65 views

Physics behind this drunken ball

I am trying to understand the physics behind this drunken ball: There is a wight inside the ball as he mentions, but where, at what position ? ...
0
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1answer
32 views

Speed, weight and force [on hold]

If a road roller of weight $W$ is rolling on the road at the speed of $X\,\mathrm{kmph}$, how much force does it apply on the surface of the road (considering a sampled surface of the same size as ...
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1answer
23 views

How is a strength of a pull spread across two springs?

I started thinking about it when I came up with a puzzle which is probably way too elementary for this site, but it is hard for me to understand clearly. I just bought this small scale thing and I ...
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3answers
76 views

Object Pushed by Multiple Forces [duplicate]

If we have a general object and we have multiple forces acting on it at several points. Assuming we know the center of mass, mass and moment of inertia of the object: Will the object rotate only ...
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0answers
24 views

Circular Motion [closed]

How do I prove the last part? I have no idea how to start.
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0answers
41 views

STEP problem (2004 paper II, mechanics)

This question says that the force exerted on a train (by its engine) when it is moving with velocity $v$ is $Pv^{\frac{3}{2}}$ where $P$ is a constant; and at velocity $v$ the resistance is $kv$ where ...
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1answer
31 views

How do we find the cone angles of the conic sections that are the Newtonian orbits?

In planetary motion, when the eccentricity of a conic section and its semi-latus rectum are known, how do we find out the cone's semi-vertical angle and angle of cutting of the cone by plane?
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0answers
27 views

Rain falling into a cart on an incline [closed]

I have a practise question in which a cart on and incline of angle $\alpha$ and starts initially at velocity $v_ 0$. Just as the cart moves off it starts raining vertically and the mass of the rain ...
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2answers
32 views

What theories or formulas are involved with velocity

What theories or formulas are involved or can be added as background information in an experiment that sees a small toy car roll freely down an incline where the surface area is altered to cause more ...
2
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2answers
64 views

Lack of rigour in usual derivation of Work-Energy Theorem

The derivation of the Work-Energy theorem usually goes as follows: You define the work done on a particle under net force $\vec{F}$ as $$W=\int\limits_C \vec{F}\cdot\mathrm{d}\vec{r}$$ And then you ...
2
votes
2answers
50 views

Why does the period/frequency of a fan slow down significantly when I taped a piece of rubber band to it?

All of this was done with a standing fan set horizontally on a table. During an experiment, I had to tape a piece of rubber band to one of the standing fan's blade and measured the period of the fan. ...
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1answer
58 views

What is “adjustable constant”?

This is quoted from A.P.French's Vibrations & Waves. Explicit differential form of linear harmonic oscillator is: $$ m\dfrac{d^2x}{dt^2} + kx = 0 \quad \& \quad \dfrac{1}{2} ...
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0answers
60 views

Bicycle gyroscopes [migrated]

I've been having this idea for some time but never worked it out properly, mainly because I lack the required engineering knowledge. I wondered if it would be possible to convert the energy you ...
0
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0answers
29 views

Incline plane problem [closed]

A string carrying a $5\times10^{-2}$kg bob hangs from the roof of a vehicle. It moves down an incline at an angle of $30 °$ with the horizontal with acceleration of $3\mathrm{ms}^{-2}$. What angle ...
0
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2answers
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 ...
1
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2answers
45 views

Energy conversion (conceptual) question

Suppose I have a electronic car. It runs by electrical energy. So when wheels rotate, mechanical energy is produced. Then why can't we convert it back to electric energy and produce somewhat unlimited ...
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2answers
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 ...