In introductory mechanics, the momentum of a particle is its mass times its velocity. In electrodynamics, the momentum of a field is proportional to the cross-product of the electric field with the magnetic field. In special relativity, momentum is generalized to four-momentum.
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105 views
Directionality of angular momentum
I was told that the sum of linear and angular momentum is conserved.
Given that angular momentum's direction as a vector is completely arbitrary (I believe there is no physical reason for choosing ...
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1answer
148 views
Rocket drive and conservation of momentum
I am currently reading through some lecture notes of Physics 1 and in a chapter about the dynamics of the mass point, there is an example covering the rocket drive.
Let $v$ be the velocity of the ...
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2answers
235 views
Connection between momentum and energy
What is the connection between momentum and energy?
Which of the answers is the correct?
A particle can have zero momentum but energy.
A particle can have zero energy but momentum.
...
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1answer
101 views
On a frictionless table, what is the angle at which a cue ball should hit another ball for it to go in?
Assume there are 2 balls on the table. Cue ball and another ball. What is the angle at which the cue ball should hit another ball for it to go in?
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1answer
71 views
How to get the new direction of 2 disks colliding?
I'm developing a 2D game including collisions between many disks. I would like to know how I can get the angle corresponding to the new direction of each disk.
For every disk I have this information ...
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2answers
154 views
Conservation of Linear Momentum with respect to a given direction
Is linear momentum conserved in any direction? More specifically, if you project all momentum vectors in a system onto another vector, will momentum be conserved?
I know that momentum is conserved ...
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3answers
267 views
Same momentum, different mass
The question is: if
A bowling ball and ping pong ball
are moving at same momentum
and you exert same force to stop each one
which will take a longer time? or some?
which will have a longer ...
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1answer
75 views
Can electromagnetic momentum be introduced at pre-university level as for electromagnetic energy?
Electromagnetic energy is introduced at pre-university level, starting with static electric energy followed by static magnetic energy. But the introduction of electromagnetic momentum usually has to ...
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1answer
152 views
Momentum And A Car Collision
I am studying an example problem, concerning the very topic mentioned in the title. In this example problem, a car has a head-on collision with the wall; the initial and final velocity are known, as ...
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2answers
965 views
Inelastic collision and conservation of linear and angular momentum
Is it possible for two spheres (a & b) to have an inelastic collision with BOTH the total linear and angular momentum preserved? I'm doing some physics simulation of some spheres attracting each ...
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2answers
341 views
When should we use the concept of Impulse/Momentum instead of Force?
In my notes it says
"The ideas of impulse and momentum is useful in solving problems where:-
a) the force F is not easily calculable (e.g. sudden impact or blow)
b) the impulse force is ...
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2answers
239 views
Simple conservation of momentum
Imagine a particle moving right at 10 mph. It enters a cylinder with an open left end and closed right end. The cylinder is moving right at 1 mph. In the frame of reference of the cylinder, the ...
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2answers
296 views
Conservation of momentum leading to damage
What would be an intuitive way to damage objects in a physics game using impulses? Since momentum is conserved, so is impulse (the change in momentum for any two time periods) in a closed system.
So ...
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2answers
109 views
Is stopping something work?
If somebody pushes against a mass moving with $3 \frac{m}{s}$ to slow it down to $2 \frac{m}{s}$, he will drain the moving system of kinetic energy. Does he do work then or does he consume work?
My ...
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1answer
254 views
Finding the mass of bed/Patient
One of my friends has a problem and we don't know how to get this done,
We want to to know the mass of a patient who is laying on a bed. One scales was put under the foot of a bed and weighed 232kg ...
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1answer
64 views
Single photon's effect on conservation of momentum?
When your looking at basic Compton theory you find that if you shoot a stream of photons at a particle (usually atoms or electrons), then you have the basic laws of conservation of momentum. The ...
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1answer
55 views
Fundamental properties of motion
The first paragraph of the Wikipedia article on the angular momentum operator states that
In both classical and quantum mechanical systems, angular momentum
(together with linear momentum and ...
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2answers
48 views
effect of vertical collision on kinetic friction and subsequent change in horizontal velocity
Suppose somehow a block of mass $m$ is moving on ground, and the coefficient of kinetic friction between the block and the block is $\mu_k$. If I drop a tennis ball(of same mass) on it from a ...
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4answers
202 views
Bat hitting a ball
When a bat hits a ball, consider two cases:
1) The batsman goes for a defense, and stonewalls it, to reduce its speed.
2) the batsman goes for a shot, e.g. a home-run, etc.
in which case will the ...
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2answers
103 views
Do photons actually generate a slight kinetic force?
My question is even though photons have no (rest) mass, do they emit a external force due to EM radiation causing electrons to be excited and jump to higher energy shells which electrons have mass ...
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1answer
67 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 ...
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3answers
130 views
Displacement with zero velocity
I know that we can rotate a deformable object using internal forces only in space. Thus we can cause an angular displacement without the use of any external forces.
The following youtube video shows ...
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1answer
99 views
Integration of constant: $\int dp = \Delta p$ in impulse formula
In University Physics, it has something like:
$$\int \sum F dt = \int \frac{dp}{dt} dt = \int dp = \underbrace{p_2 - p_1}_{\Delta p?}$$
But I thought $\int dp = p$? Though my maths is really rusty ...
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1answer
90 views
Cyclic co-ordinates implying the constant velocity motion of center of mass of a system of particles
I'm reading the section on Central Force in my textbook (Goldstein's Classical Mechanics has a similar argument in the chapter titled "The Central Force Problem", first section), where we have the ...
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2answers
53 views
Can you launch an item farther by slamming into it or accelerating it along a length
I am trying to desgin a little penny balista toy (built with a 3d printer).
The short description is that there is a track with a mass ("hammer") that slides along it. There is a stack of pennies in ...
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3answers
541 views
what is physical meaning of this partial derivative?
what is physical meaning of this partial derivative:
$$\frac {\partial p_x}{\partial x}$$
i know how do i solve it when the case is just derivative but partial derivative is a bit Hectic!.
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1answer
152 views
4-momentum and an $y$ component of momentum
I have 2 coordinate systems which move along $x,x'$ axis.
I have derived a Lorentz transformation for an $x$ component of momentum, which is one part of an 4-momentum vector $p_\mu$. This is my ...
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1answer
84 views
Spring coupled platforms & conservation of momentum - can it be solved with freshman physics?
This question came up as an exercise in a first year undergraduate course I was a TA for. It turned out to be a lot more difficult (impossible?) than anticipated...
Two platforms of mass $M_1$ and ...
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1answer
96 views
Conservation of momentum with MOND
Assuming as true the phenomenological MOND law for low accelerations ($< 10^{-10} m s^{-2} = a_0$), and considering a small mass $m$ attached to a larger mass $M$ by a faint spring (let's think of ...
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1answer
224 views
Controlling the outcome of a quantum measurement through translational entanglement
According to the paper:
A. S. Parkins and H. J. Kimble, Phys. Rev. A 61, 52104 (2000).
http://pra.aps.org/abstract/PRA/v61/i5/e052104
You can entangle position and momenta of two atoms by using ...
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1answer
169 views
How to determine n equidistant vectors from point P in three dimensions
As an assignment for uni I need to figure out an algorithm that explodes a particle of mass $m$, velocity $v$, into $n$ pieces.
For the first part of the assignment, the particle has mass $m$, ...
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1answer
478 views
Finding force exerted in an Inelastic Collision
I did a lab today in Physics in which we launched ball from a spring loaded cannon directly into a pendulum that captured the ball, held it, and swung upwards with it (representing a totally inelastic ...
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1answer
110 views
How to explain relativistic mass with 2 moving systems, but not 3?
All the visual explanations I know work in some kind of "If you are moving relative to something A, while inside A something is moving, the stuff in A has to move slower due time dilation and ...
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1answer
598 views
Converting angular velocity to linear velocity through friction
A very basic question here; it's related to this one, but not quite the same.
If a rotating rigid body (a sphere for the sake of discussion) with mass $m$, radius $r$ and inertial tensor $I$ has ...
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1answer
64 views
Where can I find the equations for “quasi” elastic collisions?
Yes, you all talk about neutrinos and spins, but I came out with this basic s**t :D
All of us learnt the basic equations of collisions, elastic (everything bounces and energy remains the same), or ...
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1answer
124 views
Inelastic collision and impulse
Suppose I have some cart moving horizontally in a straight line and with a constant velocity, and there is no friction between the surface and the cart. Now, I throw a plasticine on the cart at some ...
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1answer
261 views
Nuclear reaction: creation of deuterium
A proton p collides with a neutron(at rest) n at relatively low-energies and creates a 'deuterium-core' d:
p+n->d+γ
Find the wavelength for the photon as a function of the proton's momentum and the ...
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0answers
17 views
How do I find the force from drop shock using material properties?
I am dropping a cylindrical cast iron bar with a know elastic modulus and poisson's ratio, $E_{1}$ and $v_{1}$, onto a flat beam of elastic modulus, $E_{2}$ and $v_{2}$ so there is tangential drop ...
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1answer
71 views
Shooting a bullet at a system of blocks [closed]
So, I made this question up myself.... and I'm curious about the answer. It requires only secondary-school-level knowledge of physics:
You have a surface (ground) with a certain coefficient of ...
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0answers
48 views
A 0.1kg ball of dough is thrown up with a velocity of 15m/s. What is the momentum halfway up? [closed]
I know that $p=mv$ and (0.1kg)(15m/s)=1.5 kg m/s and the momentum at the vertex is 0, but what is the momentum halfway up?
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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 ...
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0answers
66 views
about wavefunction and vector entries
I am beginer of physics and I am studying some very fundamental idea of quantum mechanics by myself. In the introducing book I am reading, there is an example to show a particle diffraced by a slit or ...
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1answer
688 views
Spring compression and Momentum
I am asked to rate a series of elastic collisions in order of greatest time of max compression to least time of max compression for several vehicles with varying masses and velocities, which strike a ...
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5answers
173 views
Why is momentum conserved (or rather what makes an object carry on moving infinitely)?
I know this is an incredibly simple question, but I am trying to find a very simple explanation to this other than the simple logic that energy is conserved when two items impact and bounce off each ...
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1answer
145 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, ...
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1answer
157 views
Intuition of Impulse Formula $J = \sum F \Delta t$
I understand that
$$\begin{align}
J = \sum F \Delta t &= \Delta p \\
\sum F &= \frac{\Delta p}{\Delta t} \\
&= \frac{mv_2 - mv_1}{\Delta t} \\
&= m \cdot \frac{\Delta v}{\Delta t} \\
...
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2answers
51 views
Momentum, Impulse and Newton's Second Law of Motion
Newton formulated his Second Law as such:
$$\sum{\vec{F}} = \frac{\delta \vec{p}}{\delta t}$$
and of course, $\vec{p} = m \vec{v}$.
Why is it that if the net force $\sum \vec{F}$ is constant (which ...
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2answers
217 views
Center of mass of a car
This might be little of the track but my question is more on possibility of application of principle of center of mass.
The probability of a vehicle overturning depends more on the level of center of ...
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3answers
938 views
Why is force described as rate of change of momentum?
momentum = mass * velocity
Differentiating both sides leads to
force = mass * acceleration
since the mass doesn't participate in the differentiation as it is constant.
Is this a sound ...
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3answers
373 views
Will a stone thrown in space move forever?
If I throw a stone on space, in a place where gravity is equal zero, will the stone move forward forever, because no air, so no friction?
