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.
1
vote
0answers
52 views
I need help with the following Physics' questions [closed]
I need to know which formulas and the step-by-step answers for the following physics questions:
1. You throw a ball upward with an initial speed of 7.0 m/s, and it returns to your hand o.92 ...
3
votes
1answer
105 views
Does a fly get brought up to speed with a bus?
Consider a scenario where a bus is moving at a constant speed and a fly enters through a window,the fly is also flying at a constant speed.
Since the bus is not in contact with the fly and neither is ...
3
votes
2answers
117 views
Find work done by force along a path - is parameterization the only way?
$F = x^3y^4 \hat i + x^4y^3 \hat j$ from $(0,0)$ to $(1,1)$.
I am given different paths.
For example, "first along x axis and then along the y axis" is one of the paths.
Is this problem solvable ...
0
votes
2answers
139 views
Lagrange-Euler equations for a bead moving on a ring
A bead with mass $m$ is free to glide on a ring that rotates about an axis with constant angular velocity. Form the Lagrange-Euler equations for the movement of the bead.
Solution: Let us ...
3
votes
3answers
118 views
When can one write $a=v \cdot dv/dx$?
Referring to unidimensional motion, it is obvious that it doesn't always make sense to write the speed as a function of position. Seems to me that this is a necessary condition to derive formulas ...
4
votes
2answers
122 views
Conservative Force and $1/r^2$
Does the inverse square law have anything to do with conservative behavior of the central forces?
0
votes
1answer
143 views
Hooke's law, springs
A spring AB with constant k is hooked in the end A to the ceiling. At the end B of the undefomed spring is hooked a mass of weight 100N. At $t=0$ the mass is let free with no initial velocity. Not ...
2
votes
1answer
185 views
How can a satellite's speed decrease without its orbital angular momentum changing?
I have no idea what the answer is. I'm supposed to answer it within 3-4 sentences.
1
vote
1answer
179 views
Is it really possible to walk on water? [closed]
Is it really possible to walk on water or levitate in air. If not then how do some magician,s like dynemo do it simply while walking on street? And i have asked for possibility of walking on water so ...
-1
votes
2answers
170 views
Stone thrown in empty space
This is a supplementary question to What happens if object is thrown in empty space?
Via the following logic:
$$E = \frac{(mv)v}{2}\\
E = \frac{pv}{2}\\
\Delta E = \Delta p\times \Delta ...
0
votes
0answers
70 views
Weight distribution of rod [closed]
A line with mass - a metal rod of mass $X$, with a scale at each end. As the rod is vertical the scale at the bottom will read the full mass, as the rod reclines to horizontal each scale will read ...
0
votes
1answer
140 views
What happens if object is thrown in empty space?
If I throw a object in empty space, I apply a force to throw that.
Then it gains some acceleration and it's speed increases.
So will it's speed keep on increasing, or it will get stable?
If yes, ...
3
votes
4answers
327 views
Difference between torque and moment
What is the difference between torque and moment? I would like to see mathematical definitions for both quantities.
I also do not prefer definitions like "It is the tendancy..../It is a measure of ...
7
votes
3answers
282 views
Could a universe with purely Newtonian mechanics exist?
I've heard about the fine-tuning principle and how if the fundamental constants of the Universe were changed even a slight bit, life could not exist as we know it.
However, study on this subject ...
0
votes
3answers
255 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 ...
0
votes
2answers
96 views
Internal/Rotational angular momentum
I have some difficulties to understand the relation between the internal and the rotational angular momentum of a rigid body which is also known as König's theorem, so what physical intuition lies ...
2
votes
2answers
207 views
Are there any exceptions to Newton's laws?
So I am studying the laws of Newton and I'm wondering, are there any deficiencies related to the laws? I mean, somewhere where I can't use them or anything?
1
vote
1answer
55 views
Mean value of the force in a collision problem
I have the following problem:
A point with mass $m$ and speed $v$ collides with a fixed obstacle and penetrates it, stopping in a space $\Delta x$. Calculate $\Delta t $.
I understand the way my ...
2
votes
2answers
218 views
Small car colliding with large truck
A small car collides with a large truck. Why do both vehicles experience the same magnitude of force? Wouldn't the large vehicle experience less force than the small one?
6
votes
4answers
327 views
What's the exact gravitational force between spherically symmetric masses?
Consider spherical symmetric$^1$ masses of radii $R_1$ and $R_2$, with spherical symmetric density distributions $\rho_1(r_1)$ and $\rho_2(r_2)$, and with a distance between the centers of the spheres ...
5
votes
2answers
125 views
In mechanics, is shock really better expressed as jerk instead of acceleration?
Some expensive electronics or mechanical devices are designed to be shock-resistant. However, the manufacturers often market the level of shock-resistance in units of g-force (I know g-force is really ...
0
votes
0answers
21 views
There's a ball and aspring in this one [closed]
There's a spring (k= 1 N/cm) hanging from the ceiling. a ball (m= 30 g) is thrown upward and it hits the end of the spring at t=0 with the velocity v0=0.3m/s and makes the spring compressed. How long ...
0
votes
0answers
98 views
Spring with mass [closed]
A block of mass $M$ is attached to a spring that has mass $m$ and the force constant $k$. The block is placed on a horizontal frictionless surface. Find the period of small-amplitude oscillations ...
3
votes
2answers
165 views
Second law of Newton for variable mass systems
Frequently I see the expression
$$F = \frac{dp}{dt} = \frac{d}{dt}(mv) = \frac{dm}{dt}v + ma,$$
which can be applied to variable mass systems.
But I'm wondering if this derivation is correct, ...
0
votes
0answers
65 views
Mass spring system, increase mass [closed]
The question says that after a mass $m=M$ (attached to a horizontal spring) reaches its furthest point, so at its amplitude, the mass is doubled, $m=2M$.
What happens to the period, amplitude and ...
-2
votes
1answer
120 views
Newton first law of motion, braking suddenly in car
While driving down the road, if you hit the brakes suddenly, your body moves forward. Explain the reason for this.
2
votes
2answers
81 views
Shoot object into the Sun using minimal energy
Say I want to shoot a cannonball into the Sun with minimal energy (minimal initial velocity relative to Earth).
In which direction do I shoot it?
Let's neglect Earth's gravity, if that would make ...
0
votes
1answer
91 views
Propeller modelling
I need a (very) approximate model of a propeller on an aircraft.
My principal question is this: what would the relationship be between:
Propeller rate of rotation
Aircraft speed
Force generated by ...
1
vote
1answer
147 views
Force exerted on a cone
This is probably a pretty elemental question, but I can't figure out what the concept is called or how to calculate it. Say you have a solid cone shaped piece of ice, you hold it in your hand and ...
4
votes
3answers
326 views
A fly in an accelerating car
A fly is flying around in a car, the fly never touches any surface in the car only fly’s around in the air inside the car. The car accelerates. does the fly slam in to the rear window. or does the fly ...
3
votes
2answers
232 views
What is the proof that a force applied on a rigid body will cause it to rotate around its center of mass?
Say I have a rigid body in space. I've read that if I during some short time interval apply a force on the body at some point which is not in line with the center of mass, it would start rotating ...
2
votes
1answer
99 views
Transform torque from Euler angles to infinitesimal Cartesian rotations
For a certain pair of rigid bodies, I have the gradient of energy in terms of Euler angles. I want to transform this gradient to the gradient of energy in terms of rotations about the $x, y, z$ axes ...
1
vote
1answer
87 views
Weightlessness on Earth
Would the following work?
Imagine one would
1) create a straight 4000 km long tube (at ground level), following the curvature of the Earth, wide enough to hold a pod the size of an aircraft cabin;
...
6
votes
6answers
537 views
When driving uphill why can't I reach a velocity that I would have been able to maintain if I started with it?
Consider these two situations when driving on a long straight road uphill:
Starting at a high velocity $v_h$, which the car is able to maintain.
Starting at a lower velocity $v_l$, and then trying ...
0
votes
1answer
62 views
Car tires wearing in dependence on breaking system
Lets say I have two cars.
They are identical in every way, except that Car A has a normal breaking system, where most of the breaking power is inflicted on the front wheels, and some on the back, and ...
2
votes
0answers
47 views
Semiflexible discrete polymer chain
Suppose we have a 2D polymer model described by a set of 2D vectors {$\mathbf{t}_i$} ($i=1,2,\dots N$) of length $a$.
The energy of the polymer is given by:
$$
...
2
votes
3answers
145 views
In projectile motion, what does it mean for the motion along the $x$ and $y$ axis to be independent?
In projectile motion, what does it mean for the motion along the $x$ and $y$ axis to be independent?
This question is referring to the concept of projectile motions.
1
vote
2answers
91 views
Why does gravity assist transfer twice the planet's velocity?
In orbital mechanics and aerospace engineering a gravitational slingshot (also known as gravity assist manoeuver or swing-by) is the use of the relative movement and gravity of a planet or other ...
0
votes
1answer
86 views
Lagrange L4 L5 points and perifocal plane
I have 2 satellites at the L4 and L5 points and these are watching an object. Each satellite provides the angle to the object from its own position from a line parallel to the $\text{x-axis}$ of ...
2
votes
5answers
162 views
Forces acting on a point mass in a spinning rigid body
I have learned that all spinning objects will continue spinning even if no force is acting on it, and the tendency to do so is called moment of inertia. But I wonder about the fact that a single point ...
6
votes
3answers
171 views
Falling through the rotating Earth
Suppose you were standing on the rotating Earth (not necessarily Equator or the poles) and suddenly your body lost the ability to avoid effortlessly passing through solid rock.
Because the earth's ...
0
votes
0answers
47 views
An ideal toilet roll on a flat surface [closed]
Suppose we have an ideal toilet roll on a flat surface with the outer end of the roll fixed to the surface. After we give the roll an initial velocity such that the roll unwinds, what happens to the ...
1
vote
1answer
177 views
Monkey and tree - projectile motion
The famous scenario: A hunter is trying to shoot a Monkey hanging from a tree. However, this question doesn't mention the monkey jumping down from the tree or trying to escape. (The hunter uses a ...
0
votes
0answers
64 views
How to interpret and simplify Newton's first law?
I read this question where there's a lot of info and also some speculation
History of interpretation of Newton's first law
Can it be said that all that Newton's first law actually says is that ...
2
votes
2answers
122 views
Contact force betweeen 2 objects
Suppose that we have 2 objects next to each other.The object at the left is A and the object at right is B.now we have these situations:
1) we push B to the left.
2) we pull A to the left.(in this ...
1
vote
1answer
147 views
Work done in projectile motion
A projectile is shot at some inclination to the ground. It falls at another point having R distance from the initial point on the ground. Is there any work done?
If initial velocity vector is $(u\cos ...
1
vote
1answer
66 views
particle accelerator in space
I'm attempting to learn special relativity and i'm having trouble calculating velocity and momentum for each part of the system after interactions.
I wanted to know how fast a linear accelerator and ...
1
vote
2answers
172 views
Preventing a block from sliding on a plane (with friction)
Assume a small square block $m$ is sitting on a larger wedge-shaped block of mass $M$ at an upper angle $\theta$ such that the little block will slide on the big block if both are started from rest ...
1
vote
0answers
248 views
Neglecting friction on a pulley?
So, this is how the problem looks:
http://www.aplusphysics.com/courses/honors/dynamics/images/Atwood%20Problem.png
Plus, the pulley is suspended on a cord at its center and hanging from the ceiling.
...
1
vote
1answer
143 views
Projectile motion in two and three dimensions question?
So I bought this book in the library and physics fascinates me and I found this quote in the book " Galileo has proved that when any effects due to air resistance
are ignored, the ranges for ...
