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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Collar on a rim in a vertical frame [closed]

Suppose we have such construction as shown at the picture. The vertical frame starts from rest with constant acceleration $a.$ Find final angle $\theta,$ assuming no friction. Also plot $\dot\theta$ ...
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73 views

Space and motion

When we throw a ball upwards sitting in a running bus or train it directly comes to our hands but when we do the same sitting on a moving motorcycle the ball falls backwards. Why?
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124 views

Can the epicycles of the geocentric model of the solar system be dismissed due to the laws of physics?

With enough epicycles, the motions of the planets can be accounted for in a geocentric model, but do the laws of gravity make such motions impossible? Did Newton's laws not only provide a simpler ...
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2answers
196 views

Does the outflowing water create a thrust on the bucket?

Let's consider the the bucket with water, which has a small hole at the bottom. Let the bucket lift up with a constant force $\vec F$. Water in the bucket, of course, flows out of it. Questions are ...
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121 views

Reduced Three-body problem

I know that three-body problem in celestial mechanics can't be solved analytically in general. But suppose that the 3rd body is much smaller than the others, so it does not perturb their orbits. This ...
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123 views

Newton's Principia: Astronomical prerequisites?

I am planning to read the Principia but I currently have no knowledge about Astronomy. What astronomy prerequisites do I need to understand the Principia? I would prefer older books (or "treatises"), ...
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101 views

Is It Possible To Move The Earth In A Direction? [duplicate]

According to Newton's 3rd law, when an object moves upward, the Earth moves by a very tiny factor in the opposite of the direction of the object. And when the object falls back, the earth moves back ...
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120 views

Can momentum be distributed to multiple objects which travel in different vectors?

This is a question about the conservation of momentum: If there were a cluster of billiard balls floating in space and the cluster was struck by one moving ball, the cluster balls would scatter in ...
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0answers
3k views

Solve for one unknown mass in a simple pulley system [closed]

My class was given a problem where we would use a pulley system to calculate the mass of a pair of car keys. We attached 200g weights to each side of a pulley system and attached the keys to one of ...
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2answers
2k views

How does friction help the car to move forward? [duplicate]

Below is the extract from my book. There is a car with four wheel drive system and during acceleration, the engine causes the tires to push backward on the road surface. This push produces ...
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1answer
135 views

Do objects launched from Earth retain the Earth's lateral inertia (67,000mph)

We've probably all heard of the gun on a train theory. Fire a bullet that would normally travel 500mph on a train that's moving 200mph (in the same direction the train is moving) and you've now got ...
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1answer
467 views

Why does $k/m=\omega^2$ for harmonic motion? [closed]

Can anyone please give me a proof for $k/m=w^2$ in simple harmonic motion? I have tried energy conservation and Newton's laws as follows : In the case of a mass-spring system, $$F=ma =-kx\\ F=ma = ...
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64 views

Why speed of block/box reduce when force is acted?

In my physic book there is a question which is as follows;- A food shopper pushes a wood crate of cabbage heads of mass $m$ =14kg across a concrete floor with a constant horizontal force $\vec{F}$ ...
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1answer
50 views

Why we can omit some forces while applying linear momentum principle

While applying linear momentum principle, namely that if force is zero linear momentum of the system is constant, in textbook they don't count for $N$ force from $M \to m.$ This force have component ...
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2answers
224 views

Time reversal in simple *solution* to equation of motion

Consider the solution to the equation of motion for a particle with a constant acceleration: $$ x(t) = x_0 + v_0t + \frac{1}{2}at^2.$$ If I let $t \rightarrow -t$, then the equation becomes: $$ x(-t) ...
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Why do we need to know the shape of the slide to find the time to slide down it?

In my physics book after this solved example: A child of mass $m$ is initially at rest on top of a water slide at height h = 8.5m above the bottom of the slide. Assuming that the slide is ...
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1answer
245 views

Why does one multiply physical constants in physics equations?

What I mean by this is for example if you take the equation F=ma, why is it that you multiply mass by acceleration? How do we know this concept that we define as the force is best described by m times ...
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Changing Earth angle of revolution

As a follow-up to the two previous questions What is the scientific reason for the inclination of earth's rotation axis? and How much effort would be required to fix the Earth's rotation? ...
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461 views

The two-body problem - planets orbiting each other

I am taking a course in classical mechanics these days, which evolves the two-body problem. I need some clarity about the following questions, if possible. Consider two stars orbiting around each ...
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0answers
44 views

An old mechanic paradox [duplicate]

I came across this question in Mathematical Recreations and Essays. If a rope (whose weight may be neglected) hangs over a smooth pulley; it has one end fastened to a weight of 10 stone, and the ...
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1answer
134 views

Why is kinetic energy defined as $(1/2)m v^2$? [duplicate]

What is special about $(1/2)m v^2$ that makes physicists believe that it is a representation of kinetic energy?
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2answers
465 views

Question about impulse and momentum

Check this question first please My question is: Why can't I use equations of motion to get the final speed after rebounding?Acceleration not equal to $9.8 \text{m/s}^2$ or the intial after ...
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1answer
104 views

Transfer between translative KE and rotational KE in a rigid body

I have been inspired by some sci-fi cannons that seem to operate by initially spinning up a projectile inside the cannon, and then suddenly firing the projectile out at high speed. Now, I am wondering ...
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3answers
216 views

Mountain and a feather dropped from same height. Which hits Earth first?

Let's assume: the feather has a mass of $0.006$kg the mountain has a mass of $6 \times 10^{15}$kg the earth has a mass of $6 \times 10^{24}$kg no air resistance both objects released at the same ...
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2answers
1k views

Dropping Objects of Different Masses

It's a commonly taught principle that dropping two objects of different mass at the same height, given that there is no air resistance, will result in the two objects making contact with the ground at ...
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1answer
110 views

Why doesn't a parachutist, according to Newton, “fall” upwards (because drag is larger than gravity)?

Part of the second law states that an object will accelerate in the direction of the unbalanced force. However, I've been thinking about parachuting and skydiving a bit lately, and I know that when ...
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310 views

Experiment to verify a spring constant

In my high school physics class, I had students do a Hooke's Law lab to measure an unknown spring constant. Once we compared everyone's data we came up with a class value for $k$ of 253 N/m. We then ...
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What are the major differences in group-skydiving as opposed to “single” skydiving?

Surface area/the cross-sectional area is greatly increased, so my thinking is it should decrease terminal velocity as well as a couple of other factors. But mass changes too (since there would be more ...
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191 views

Kinematics equations of motion find x position in 2D from height

I have a question and I thought of 2 possible ways to answer it however the resulting answers are different which means I must be doing something wrong in my calculations. All the below happens 2 ...
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98 views

Why and how is acceleration absolute?

Is there a testable model which explains why rotation of an object in space and straight-line acceleration appear to be absolute while uniform translation is relative? I know of Mach's explanation, ...
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1answer
94 views

Motion of a wheel with an added mass to its edge [closed]

Imagine a wheel with homogeneous mass distribution, but there is a mass concentrated to its edge at a specific point. The wheel is rotating over a horizontal surface with a given initial velocity. How ...
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3answers
2k views

When is tension constant in a rope?

Suppose we have a massless rope with pulling forces applied at each end. In which scenarios is the tension in the rope constant throughout? For example if there is a knot in the rope the tension is ...
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848 views

Force and direction of velocity

If the angle between force acting on a particle and velocity of particle is zero degree, the value of velocity will increase. If this angle is 180 degree, the value of velocity will decrease. If this ...
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2answers
92 views

What logic did Newton give in support of using relative spatial measurements? [closed]

The crux of space-time is that it is one thing to have abstract concepts of absolute space & time,and it is other thing to describe the actual motion of an object in terms of measured changes of ...
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1answer
121 views

Is there any net external force acting on the universe?

If we consider the universe as a system, is there any net external force acting on it? I am thinking of whether or not the center of mass of the system moves. If there is no such a net external force ...
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1answer
176 views

Moment of Inertia and Linear Dimensions

For similar solid bodies made from constant density, how does the Moment of Inertia about a particular axis vary with linear dimensions? This is from an school textbook. I have covered all of MI ...
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3answers
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Is work done = change in KE, or change in mechanical energy?

Starting from $F = ma$ we get: $$ F=m\frac{dv}{dt} = m\frac{ds}{dt}\frac{dv}{ds} = mv\frac{dv}{ds} $$ which leads to the work done: $$ W = \int Fds = \int mvdv = m\frac{v^2}{2} - m\frac{u^2}{2} ...
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Work done: kinetic energy or area under F-ds curve?

Starting from $$F=ma = m \frac{dv}{dt} = m \frac{ds}{dt} \frac{dv}{ds} = m v \frac{dv}{ds}, $$ leads to work done = integral of F.ds = integral of mvdv = change in KE. Suppose a variable force is ...
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364 views

Rotational Inertia of a Disc and Subsequent Acceleration

This is more of a conceptual problem as opposed to anything wrong with the maths! (I think/I hope! :) ) But essentially the problem states: imagine a circular flat disc of radius $R$ and of mass ...
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Transformation for rotating frame [duplicate]

Can anybody please explain the derivation of transformation of a frame rotating with constant angular velocity w.r.t. a stationary frame. It can't understand it from my book. The derivation started ...
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3answers
238 views

Centripetal and centrifugal force

If a stone is rotated with the help of a rope, then both centripetal force and centrifugal force will be liberated. The magnitude of that forces are same, but direction of them are opposite to each ...
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96 views

Forces acting on a body-slope system

Suppose you have a wedge on a table with length $l$ and mass $M$. The angle between the slope and the horizontal direction is $\alpha$. You also have a point of mass on the top of the wedge with mass ...
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95 views

Will relativistic glider cause lower gravitational force in Newtonian gravitation?

In the articles The relativistic glider and The relativistic glider revisited, the relativistic glider is proposed where a quasi-rigid body can slow down its fall under gravity without any reaction ...
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62 views

Intuition of centrifugal force [duplicate]

I heard that centrifugal force does not really exist; that it is made as opposite substance to centripetal force. Is it true? Could someone define for me what centrifugal force is in terms of vectors ...
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1answer
173 views

Normal force on object on a curved 3D surface

Let's imagine we are on the top of some axisymmetric surface. Let it be $r = r(z)$ in cylindrical coordinates $\left(r,\varphi, z\right)$. It can be a sphere, which we have discussed in my previous ...
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Why does the pressure sensor give the same value of pressure no matter how it is oriented?

Let a small pressure-sensing device be suspended inside a fluid-filled vessel. ... We find by experiment that at a given point in a fluid at rest, the pressure has the same value no matter how the ...
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102 views

Which formula is correct for the velocity of a mathematical pendulum?

Suppose I have a mathematical pendulum swinging in a plane, and the angle between the vertical direction and the pendulum is $\phi(t) = \phi_0 \cos\omega_0t$. The length of the pendulum is $l$, its ...
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I can make the mechanical energy 0 or in fact anything. Is this normal?

We let the rope fall with $\alpha = \pi/2$ (no initial velocity). if I choose the original of potential energy as the picture indicates there, this means that: $$E_m = E_{pe} + E_c = \frac12mv^2 ...
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72 views

A parameter to quantify instability in flight

Suppose I have plotted the body angles of a flying aeroplane.I have two such plots. One of a normal plane, and the other plot in which a primary sensor of the aeroplane is removed. So with the absence ...
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374 views

If reality is relative, then what about Newton's bucket argument?

There is nothing outside the universe. - Lee Smolin So, there can't be any absolute frame. Everything must be measured relative to an entity that exists in the universe. Thus, space ...