Questions tagged [newtonian-mechanics]

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 concepts, use [classical-mechanics]. For Newton’s description of gravity, use [newtonian-gravity].

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3 answers
269 views

If the net external moment on a body about a point is zero

I was told that If net external moment of some forces is zero about a point, then the net external force passes through the point. I know it's not true in general, what was the special condition ...
0 votes
5 answers
526 views

How do you calculate the distance from center for centripetal force equation for long objects such as board or a hammer?

I am trying to calculate the centripetal force for an enlongated object like a fan blade. Where do I measure to to get the distance from center. Would I measure from the center to the end of the ...
25 votes
7 answers
3k views

Is it correct to say that it is theoretically impossible for perfect rigid bodies to exist?

If perfect rigid bodies were to exist, then consider a scenario in which two rigid bodies of equal masses moving with velocities of equal magnitude but opposite in direction colliding against one ...
2 votes
1 answer
29 views

Dropped ball entering curved surface: Bounce or not?

Referencing this question here of a ball being dropped onto the end of a curved bowl: Velocity of ball sliding on bowl. Need to understand why vertical velocity of bowl is 0 and ball is not What is ...
0 votes
1 answer
31 views

Rotation of a rigid body

I am dealing with the motion of rigid bodies and in studying it I came up with some questions about the nature of rotation. (1) Does a rotation always have to happen about one fixed axis? (2) Is ...
0 votes
1 answer
185 views

Wind Power in a Wind Tunnel

Two questions in one day! What? Okay, so the power equation for air flow is as follows: $$ P = 1/2 \cdot \rho \cdot A \cdot V^3 $$ In a wind tunnel due to the Bernoulli principle as the area ($A$) ...
0 votes
1 answer
9 views

End motion of an empty spherical shell with a ball rolling on it's inner surface

Let's picture an empty sperical shell in inter galactic space or beyond. Inside this shell, a ball is rolling on the inner surface. Because of friction and the centrifugal force the ball exerts on the ...
0 votes
1 answer
245 views

Slip definition that works in game

Wikipedia article gives us the following 2 equations: $$\%_{slip} = \frac{\omega r - v}{|v|} * 100$$ (The use of $v$ modulus makes it work in all directions. It is multiplied by 100 to get the ...
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0 answers
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Which one is better for robotic arm: planetary gear VS pully and pinion? [closed]

I have been watching different DIY robotic arm builds on youtube, most use either planetary gear or pully and pinion. what would be the advantages of using one over the other?
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0 answers
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Is there a function or equation that can trace the trajectory of a space rocket's motion on the three coordinate axes $(x ,y ,z)$?

To be honest I'm working on a project at the university which is a simulation of launching a rocket into space The problem here is that this simulation needs to be realistic enough for my programming ...
0 votes
2 answers
38 views

A question regarding work done by tension force in a simple pendulum

Consider the picture given below to show the free body diagram of a simple pendulum going to and fro and not a conical pendulum. I have read in my physics book that work done by tension force is zero ...
-1 votes
2 answers
44 views

Can an object move with a constant velocity without balanced forces?

Can an object move with a constant (magnitude) velocity without the balanced forces? As an object which is balanced with the frictional force continues moving at a constant velocity, acquired till ...
2 votes
2 answers
46 views

Doubts about direction of normal contact force acting on a tilted rod supported by another body

I'm confused about the direction of the normal contact force acting on a body supported by another body. I have read the following : If a body is being supported by a surface, the normal force acting ...
0 votes
0 answers
197 views

Differential equations of a forced coupled spring-pendulum system

Currently working on a problem and I can really figure out how to write the differential equations for it. Here's the situation: So we have a mass $m$ tied to the wall with a spring of constant $k$. ...
10 votes
1 answer
869 views

The Role of the Virtual Work Principle

Lanczos' masterpiece "The Variational Principle of Mechanics" has, on page 76, the following statement: Postulate A (virtual work): The virtual work of the forces of reaction is always zero for any ...
0 votes
2 answers
746 views

Force exerted on ground from a slipping wheel

I am trying to do some car calculations for a game. I have a tyre (radius $r$, inertia $I$) rotating around it's axle with an angular velocity $\omega$ faster than the center of mass is moving across ...
2 votes
3 answers
928 views

Do electrons have inertia?

I don't know quantum mechanics and know a little bit about mechanics and a very little bit about subatomic particles but I am just a curious to know the answer to my question. My question is if '...
1 vote
3 answers
254 views

Acceleration of free fall at different parts of Earth

“free fall is any motion of a body where gravity is the only acceleration acting upon it.” -Wikipedia Question 1 - If an object is falling freely, will it follow the Earth’s rotation too? Or will ...
11 votes
3 answers
290 views

Is friction required for knots (not hitches or bends) to hold fast to a rope?

Using rope with idealized coefficient of surface friction approaching zero, that is in all other ways typical (typically stretchable, compressible, flexible and twistable), is it possible to tighten a ...
22 votes
7 answers
11k views

Zero velocity, zero acceleration?

In one dimension, the acceleration of a particle can be written as: $$a = \frac{dv}{dt} = \frac{dv}{dx} \frac{dx}{dt} = v \frac{dv}{dx}$$ Does this equation imply that if: $$v = 0$$ Then, $$\...
2 votes
5 answers
59 views

How does a sliding object stop moving by the effect of kinetic friction, if kinetic friction is constant and Fk can't be greater than Fapp on its own

The kinetic friction is constant. So if say, I apply a force of 20N on an object and the kinetic friction is 13N, then how does the object stop moving after some seconds. I believe that kinetic ...
2 votes
6 answers
175 views

Is work done by torque due to friction in pure rolling?

This question has been asked and answered numerous times. I went through almost all of them and found no consensus. I found that all of the answers can be divided into two categories: Friction does ...
1 vote
1 answer
211 views

Confusion regarding torque and calculating linear/angular acceleration of an object when a force is applied a distance from its center of mass?

From what I have read/learned about torque, it appears that it is derived based on the idea that applying a force farther from a point about which an object rotates increases the rotational force ...
0 votes
1 answer
21 views

Transfer mechanism of two particles in laboratory coordinate [closed]

There is two particles' collision with angles theta for M1 and phi for M2. The initial velocity of M1 is V0 and of M2 is 0. The collision follows the conservation of energy and momentum. Three ...
0 votes
2 answers
2k views

Moment of force about a point definition

In defining the moment of a force about a point as "the tendency of one or more applied forces to rotate an object about an axis [going through a point, hence also about a point]", I see it logical to ...
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2 answers
49 views

Angular Momentum about a Point

I am confused by two different definitions of the angular momentum of a particle P about a moving point Q, with point O as the origin of the inertial frame. I learned the first definition from my ...
-4 votes
1 answer
50 views

Its a physics exam question, I and my friend don't understand the theory and mechanics behind it.(Don't tell the answer, just need how to visualize) [closed]

Two spheres each of mass m are connected by string of length 2l, are kept on a smooth horizontal surface. A vertical force F is applied at the middle of the string. What is the max value of F for ...
4 votes
1 answer
43 views

Moving body is collided with a spring system.Why there is a difference in maximum compressed distance for different observers?

Suppose a body of mass m moving with velocity collides with a spring system.The event is being observed by two observers, one at rest and one moving with a velocity v opposite direction to that of the ...
4 votes
7 answers
932 views

Trying to understand Newton's Second Law [closed]

If I apply a force on an object at rest and it’s velocity is constant (after force is applied) wouldn’t that mean that the acceleration is 0? Then how would $F=Ma$ make sense? My thinking here is that ...
4 votes
5 answers
3k views

Reconciling Units in Classical System Analogies: Why Does Torque Have Units of Energy?

In classical physics we often cast an analogy between translational and rotational systems Force < > Torque Energy < > Rotational Energy Momentum < > Angular Momentum and considering SI ...
-3 votes
0 answers
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Newton's Law of Gravitation - Inverse Square vs Cube Law [closed]

When calculating the location of gravitational equilibrium between earth and moon, it is found to be within 500km from the center of the moon. However, the same is found to be more sensible (72,000km ...
0 votes
1 answer
22 views

How to find the force exerted by continuous jet of water on a wall? [closed]

Suppose, the water is flowing at a speed of $2m/s$. The cross-sectional area of the opening is $0.03m$, and the water is hitting the wall at right angles. Assuming the water doesn't rebound, how will ...
0 votes
0 answers
26 views

Rolling without slipping on a curved surface [closed]

Here, we have a cylinder (centre B) rolling without slip on the rounded edge of a table. The rounded edge is a quarter circle centred A. Q is where the rounded edge meets the horizontal surface of the ...
2 votes
3 answers
735 views

Tension in a rotating object

I'm somewhat stuck on this very simple question, but I can't convince myself of a satisfactory answer. I tried to look through the previous questions asked to avoid asking a duplicate I hope. Any ...
0 votes
1 answer
21 views

What is the action pair of normal reaction in case of bike riding along a curved vertical wall

I was reading about a situation in my brother’s physics textbook where a bike is riding along a curved vertical surface. It’s mentioned there that normal reaction provides the centripetal force and ...
0 votes
2 answers
29 views

Maintaining the balance of a rod of uniform density

Assume a rod which: is of uniform density $\rho$. is a metre long. The rod is balanced on a knife edge at 58 cm. mark (in the notation where the extreme left side is assumed to be 0). To the extreme ...
2 votes
3 answers
523 views

Rod's Kinetic Energy in the pendulum problem

On the MIT OCW for engineer dynamics the cart pendulum problem is solved by using the Lagrange Method here. This is a 2D problem, so rotation only occurs on the Z axis. While obtaining the rotational ...
2 votes
1 answer
28 views

What is the work done by friction on a body from the perspective of different observers using the formula $-μmgl$?

Consider two observers moving with respect to each other at a speed $v$ along a straight line. They observe a block of mass $m$ moving a distance $l$ on a rough surface. The change in KE of the block ...
-1 votes
1 answer
37 views

Concept of work [closed]

How was the concept of work and energy invented in physics? What is the actual idea behind work and energy? Why are distance and force specifically used to define work, why not time instead of ...
0 votes
0 answers
20 views

Find interval between scucessive conjunctions

The maths here doesn't seem to be too hard, but for some reason I can't quite figure out what to do: Consider two planets orbiting a star in circular orbits with periods $T_1$ and $T_2$. What is the ...
6 votes
2 answers
6k views

Is a chain REALLY only as strong as its weakest link

I heard this quote a lot (especially from my teachers) and I always wanted to know whether or not it was actually true. I think that its partially true; a chain with one weak link is weaker than a ...
0 votes
2 answers
1k views

Would a car tow rope withhold an adult person?

I am not exactly sure how the physics work here. If we take a car tow rope, which is manufactured for towing a 3500 kg car and we actually start towing such a car on this rope, what force do we really ...
0 votes
0 answers
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The work done by tension and normal forces are conservative or non-conservative? Give reasons [duplicate]

The work done by tension and normal forces are conservative or non-conservative? Tension as well as normal forces does work but has no field. Simultaneously their work is not always path dependent. ...
2 votes
1 answer
291 views

Capstan equation with only one end of rope under tension

The capstan equation will give me the relation between the tension force at both sides of a rope wrapped around a cylindrical object, but what happens in this situation where the 'rope' is something ...
0 votes
1 answer
84 views

Gravity Differential Equations

I was just messing around with Newton's Law of gravitation, when I had the idea of converting Newton's Law into differential form (more or less like Maxwell's equations). I did the following: #1 ...
3 votes
3 answers
1k views

G-force: difference between gravity and acceleration of an object

I'm trying to simulate the perception of weight by a human in a system but I'm struggling to treat gravitational acceleration and other accelerations in the same way. As I understand, when I stand on ...
1 vote
1 answer
146 views

The torque in Euler's equations for rigid body rotations

In Taylor's Classical Mechanics, it is said that the equations are generally difficult to use because the components $M_1,M_2$ and $M_3$ of the applied torque as seen in the rotating body frame are ...
0 votes
0 answers
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Finding equation for acceleration of a mass connected to a massless spring [closed]

If a mass of $ 5$ kg connected to one end of a spring is released from the elongated position and its corresponding angular velocity is governed by the equation $ \omega =t^3+t^2+1 $ then what is its ...
0 votes
1 answer
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Konig's Theorems

In the proof of Konig's Theorems the following identity is used: $$ \underline{v_i} = \underline{v_i'} + \underline{v_c} $$ which is the law of transformation of velocity when passing from the ...
1 vote
1 answer
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On general covariance

If newton's theory could be formulated in the language of differential geometry (symplectic manifolds), what do we really mean when we say that the theory is covariant under the Galilean group when it'...

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