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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Question about Galilean transformation

I'm just learning about relativity, and every equation I see for a galilean transformation of frame $S'$ (moving with uniform velocity in the $x$-direction with respect to frame $S$) is $x'=x-vt$, ...
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3answers
63 views

Different results to a basic question ( Newton's law and perservation of momentum)

Trolley with mass of $m_0=1 \ kg$ is moving without friction on the railway track. It is raining so there is a constant mass flow of water $\Phi_m=0.1\ kg/s$. Constant force $F=0.1 \ N$ is ...
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2answers
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Does the coefficient of restitution matter in a collision?

Suppose two particles are colliding. Let initial velocities be $u_1$ and $u_2$ .Their final velocities are $v_1$ and $v_2$. Now $u_1$ and $u_2$ are known. By intuition I can understand that $v_1$ and ...
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1answer
36 views

A moving inclined plane with block problem

I'm trying to solve for a challenging problem : a moving inclined plane with a block I want to solve for the acceleration components for the block and the plane and the normal force acting on the ...
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1answer
20 views

Normal force on varying mass

A cart filled with a mass $m_0$ of sand leaks it at a constant rate of $\mu \ \mathrm{kg/s}$ through a hole at the bottom of the cart. Suppose that the cart is moving on rails. Find the ...
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2answers
424 views

Which force is responsible for victory in tug of war?

I'm confused: In a tug of war game on rough ground who will win? The one who applies greater force on the rope or the one who applies greater force on ground?
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2answers
38 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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320 views

The acceleration vector of a simple pendulum

In this picture the acceleration vector $\vec{a}$ points upward when the pendulum is halfway Click To see animated GIF But according to this picture, the force acts tangentially: Which means the ...
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2answers
82 views

Two expressions for potential energy in the gravitational field of the earth

Let $M$ be the mass of the earth, considered as a point mass, then the potential energy of a point with distance $r$ away from the center (assume $r > \textrm{radius of earth})$ is $$ U(r) = ...
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5answers
133 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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1answer
58 views

An oscillating skateboard

A half pipe of a skateboard park consists of a concrete trough with a semicircular section of radius 5m, I hold a frictionless skateboard on the side of the trough, pointing down toward the bottom and ...
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2answers
71 views

Calculating the rate at which a car turns

This is going to be difficult to describe, as I have no real concept of this sort of physics, so please bear with me. If this is too much or beyond the scope of this website, I apologize. I am making ...
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3answers
31 views

Work done by gravity on a ball & the ball on earth

I have studied today that if a ball was to fall a certain height, then the work done by gravity on the ball would equal the work done by the ball's equal and opposite gravitational pull. By $W=Fd$, ...
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1answer
84 views

Rotation and fictitious forces

A bug eats through an apple and forms a vertical, infinitesimally thin canal parallel to the vertical diameter at a distance $\frac{R}{2}$ from the center. The apple rotates at angular velocity around ...
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1answer
2k views

Is angular momentum always conserved in the absence of an external torque?

Consider either the angular momentum of the earth around the sun or equivalently swinging a ball horizontally on a string. I know that with respect to the point of rotation of the swinging ball, ...
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1answer
51 views

“Rocket in a box” thought experiment

Here's a thought experiment that I came up with a while ago. It might be hard to visualize, so I'll describe it as best I can. Take a rocket in a vacuum, in outer space. Attach a large "box" to the ...
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0answers
42 views

Infinite Atwood (pulley) system - what's wrong with this? [on hold]

Each block has mass $m$. We are finding acceleration of topmost block. Assume the tension $T$ acting on topmost block and acceleration $a$ in upward direction. Then tension on second block is ...
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2answers
39 views

Time of flight for a projectile with stated initial velocity and size at various distances

I've been mooching round the internet looking for an answer to this one and can't find a ready resource, hence the question. In short, I'm trying to discover the flight time of a shotgun pellet at ...
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2answers
1k views

What causes light to move through a vacuum

I was looking at rockets and stuff and thought about how they move through a vacuum using newtons 3rd law, and then I started thinking of any other ways you could move through a vacuum without using ...
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1answer
21 views

Why is there a static frictional force on an object that rolls without slipping?

It is clear that if a frictional force must exist on an object that rolls without slipping, it must a static frictional force because the contact point of the object with the ground does not move. I ...
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4answers
93 views

Turning a car on a perfect surface

Say you have a car with perfect wheels and a perfect surface with so much friction that it never skids. When the car is traveling forward, the wheels INSTANTANEOUSLY turn 90 degrees. Does the car ...
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1answer
31 views

Why potential energy of external force on particle attached to spring is equal to full force multiplied by full displacement?

I am having quite difficult time to understand the meaning of total potential energy on spring. All references I read say that the total potential energy on particle attached to spring is: ...
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2answers
129 views

Why does moment of force depend on the perpendicular distance?

Couyld anyone explain how the lecturer concluded that $$(\underline{r_2} - \underline{r_1}) \times \underline{H} = \underline{p} \times \underline{H}$$
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5answers
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A force opposing Gravity

Every Action Has An Equal and Opposite Reaction (Newton's Third Law.) If this is the case, does gravity have an equal-opposing force? From asking around I still haven't got a very clear answer; ...
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2answers
64 views

Inertial frames

I'm just starting my study of relativity, and I have a rough understanding of the connection between inertial frames, newton's laws, and galilean transformations, but I'd probably benefit more if ...
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3answers
492 views

Conservation of Mathematical Constraints when deriving Energy and Momentum from $F=ma$

Background: Starting from $F = ma$, integrating with respect to time, and using basic calc, one can derive $\int Fdt = m (v_f - v_i)$ Starting from $F = ma$, integrating with respect to distance, ...
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3answers
66 views

Foucault pendulum initial velocity

This is a basic question I can't solve and it seems it is not addressed on the web. Sorry for my lame painting skills. Assume we have a foucault pendulum suspended in the north pole. the pivot is ...
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0answers
33 views

Length of the missing part [on hold]

I have got a very interesting question. A car is driving this way on the picture down. In the looping is a missing part. The radius of the looping is r = 40cm. The car starts at the height h = 3r. If ...
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0answers
24 views

A ball rolling in a bowl [on hold]

There is a small ball with a radius of 2 mm inside of a bowl with a radius of 22 mm. If the bowl is tilted 1 degree in any direction, what does the slope of the bowl need to be in order to get the ...
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7answers
2k views

Why do we fall down when the bicycle slows down? [duplicate]

My question is: It is easy to balance a bicycle when it is moving at a fairly high velocity, say 7 m/s or 25 km/hr. But when a bicycle slows down, it is hard to keep it upright, and the person riding ...
2
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1answer
90 views

What is the constant $K_1$ in these orbital equations?

I want to compute the derivatives of argument of periapsis and longitude of the ascending node of the orbit of a GPS satellite from the following formula. $$\frac{d\Omega}{dt} = -K \cos{i} \\ ...
3
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2answers
95 views

Optimal speed for the water wheel

The hydroelectricity plants extract the potential energy of highly deployed massive object (water) as it falls down. Without turbine, all that energy would be converted into speed (kinetic energy) at ...
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1answer
31 views

Amplitude of motion for a cart on an inclined plane attached to a spring

A very practical question. So, let's imagine that we have a small cart attached to a spring lying on an inclined plane. If I move my cart by 10 cm (measured as if there were a ruler lying along the ...
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1answer
342 views

1D Kinematics - Relative Motion involving non-inertial frames of reference

I recently came across a question involving non-inertial frames of reference. I didn't quite understand the way it had been solved due to some conceptual confusion regarding certain deductions made to ...
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4answers
109 views

What do you exactly mean when you say that momentum is conserved?

I am taking for granted that when we say that something is conserved it is understood 'in its full integrity'. Energy is represented by a number (of J, or other) and is usually conserved. But ...
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2answers
76 views

What physical conditions would allow for this kind of perpetual seesaw

I'm working with a simulator(Box2D) and need to create these conditions. I have a perpetual seesaw with two objects on either side. I'd like for the following conditions to be met. The first ...
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1answer
38 views

At the instant of release of an object from rest. Is the only force that can act its weight?

Q3 from a mechanics exam past paper: I can do parts i) and ii) but for iii) in finding the angular acceleration, i used $C=I\alpha$, where $C$ is the applied couple or torque, $I$ is the moment of ...
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2answers
111 views

How can Excel be used to model the flight of a rocket? [closed]

Firstly, sorry for any silly mistakes or improper use of this website - this is my first time using it! I am trying to use Excel to model the flight of the Apollo 11 Saturn V rocket using the real ...
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0answers
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calculate gravitational force [on hold]

an object weighs 977N on the surface of the earth and 244.25N if the earth is remoulted. The radius of earth is 6.4×10$^4$m and its mass is 6×10$^{24}$kg. Calculate the radius of remoulted earth and ...
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1answer
317 views

Spring system - 3 DoF system and its properties while changing stiffness

I was given the attached 3 degree of freedom spring system with the purpose of analyzing it. I came up with the following equation of motion and then I ran Matlab to calculate the corresponding ...
3
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1answer
44 views

Relationship of multiple particles under collision [on hold]

Consider 3 particles. All 3 particles travel along the x-axis. The 1st particle possesses some mass, m, and its initial position is somewhere on the negative x-axis. It has some (positive) velocity ...
2
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1answer
58 views

Conservation of linear momentum, when is it conserved?

Will Linear momentum be conserved in a non-inertial frame of reference? In other words what is the fundamental condition for linear momentum to be conserved? Also which is more fundamental- Newton's ...
9
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4answers
453 views

Is the second law of thermodynamics a fundamental law, or does it emerge from other laws?

My question is basically this. Is the second law of thermodynamics a fundamental, basic law of physics, or does it emerge from more fundamental laws? Let's say I was to write a massive computer ...
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3answers
2k views

The direction of friction for a car wheel

In this particular example shown the image below (from engineering dynamics - Meriam), I do not figure out why the direction of friction is in direction of the translation of the car? Or I just ...
2
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3answers
214 views

Can I make a rod in the vertical plane move with its one end on the ground in a slanting position?

Consider a rod kept vertically on the ground. I keeps the rod in a slanting position making some angle with the horizontal. Can I now move this rod along the horizontal plane by applying a force at ...
3
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0answers
38 views

How to find tension in the cantilever brakes?

In the left side example of cantilever brakes, how do I find the tension in strings DE and DC, in terms of T. According to me applying force balance equations, horizontal and vertical forces should ...
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1answer
87 views

In a 2-body problem, when is the moving path closed?

In a 2-body problem is it true that, in all situations, the moving path is closed? In which cases are the paths closed? Fixing the coordinate system or fixing one of the bodies gives us different ...
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2answers
76 views

What is the “associated scalar equation” of equations of motion?

In an essay I am reading on celestial mechanics the equations of motion for a 2 body problem is given as: $$\mathbf{r}''=\nabla(\frac{\mu}{r})=-\frac{\mu \mathbf{r}}{r^3}$$ Fine. Then it says the ...
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3answers
101 views

Energy Required To Push Up a Slope

I'm having a bit of trouble with this problem: A $5.0\:\text{kg}$ block is moved up a slope with constant velocity of $2.5\:\text{m/s}$. The amount of force required to push the block up the slope is ...
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2answers
67 views

Force Diagram for K&K 2.13 [closed]

I have been (independently) working on Problem 2.13 in Kleppner and Kolenkow's An Introduction to Mechanics and come to an answer which conflicts with the hint the authors provided in the book. The ...