Tagged Questions
0
votes
1answer
25 views
Kinetic energy when $F(t)$ graph is given
The very basic problem here is that the point where this graph ends is ambiguous. I mean, what is the corresponding $y$-value for the point whose $x$-valu is $4.5s$? Then I think we should find the ...
0
votes
0answers
28 views
Schrodinger equation in momentum space [duplicate]
I have a problem this is:
When I solve the Schrodinger equation in momentum space, I had done as this:
$\begin{array}{l}
i\hbar \frac{{\partial \Psi }}{{\partial t}} = - \frac{\hbar ...
0
votes
2answers
46 views
Simple conservation of momentum and frame of reference problem
I'm making a very simple physics engine based on momentum, and I'm solving what response to use for a collision from each involved object's frame of reference. However, something about how I'm ...
3
votes
1answer
71 views
Conservation of momentum in collision of two bodies
Suppose we have some ramp on wheels of mass $M$, standing on a
frictionless surface. A cart of mass $m$ moves with a certain velocity
$v$ towards the ramp. The cart moves up the ramp ...
0
votes
2answers
144 views
Perpendicular Elastic Collision (different masses, different velocities)
I'm stuck on a mechanics problem and I can't make any headway past momentum and kinetic energy being conserved. Here is the problem:
Two hover cars are approaching an intersection from ...
0
votes
0answers
34 views
Question about momentum [closed]
Starting at rest, two students stand on 13.7-kg sleds, which point away from each other on ice, and they pass a 5.50-kg medicine ball back and forth. The student on the left has a mass of 58.7 kg and ...
3
votes
2answers
165 views
Firing machine question
Suppose we have a firing machine on a frictionless surface at point $x=0$. It fires a bullet of mass $m$ every $T$ seconds. Each bullet has the same constant velocity $v_0$. There's a body of mass ...
0
votes
0answers
35 views
Changing Momentum [closed]
A high school football player hits and pushes a tackling dummy during practice. The following graph shows the amount of force that acts on the player.
a. What is the impulse that acts on the ...
0
votes
0answers
28 views
Changing Momentum [closed]
Changing Momentum
The illustrations show two ways of providing impulse to change the momentum of a vehicle. In the top illustration, the vehicle collides with a massive concrete barrier. In the ...
0
votes
0answers
37 views
Conservation of momentum in two body collision [closed]
A neutron of mass $1.7\times10^{-27}\ \mathrm{kg}$, travelling at $2.7\ \mathrm{km/s}$, hits a stationary lithium nucleus of mass $1.2\times10^{-26}\ \mathrm{kg}$. After the collision, the velocity of ...
-1
votes
1answer
57 views
Determine KE of electron given momentum & mass [closed]
Some info:
wavelength of electron: $2.78 \times 10^{-10}$
momentum of electron: $2.38 \times 10^{-24}$
Determine KE of electron. In a provided hint: $KE = \frac{p^2}{2m}$. So I have:
$$KE = ...
0
votes
1answer
72 views
Newton's second law?
$F=ma$. A car strikes a wall at 60 mph. Its acceleration is zero at the time. The force of the car against the wall or vice versa is? To look at the car the force is not zero. Please explain.
1
vote
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 ...
0
votes
2answers
56 views
Minimum $E$ of $p\bar{p}$-collision for $q\bar{q}$ pair with mass $m_q$
I am currently working out the energy required to create a particle anti-particle pair from a collision of a proton travelling along the x-direction with an anti-proton which is at rest. The particle ...
2
votes
2answers
113 views
Movement of man and ladder and their center of mass
Suppose there is a massless frictionless pulley.
A rope over it carries a mass $M$ and on other side carries a ladder of mass $(M-m)$ and a man on that ladder, of mass $m$. Now the man starts ...
0
votes
2answers
65 views
Conservation of Momentum from Recoil Speed
A gun has a recoil speed of 2 m/s when firing. If the gun has a mass of 2kg and the bullet has a mass of 10g (0.01 kg) what speed does the bullet come out at?
The gun has zero total momentum before ...
1
vote
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 ...
1
vote
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 ...
1
vote
1answer
70 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 ...
0
votes
1answer
161 views
Calculating a 2D collision between two perfectly circular disks
Assume I have two disks, $p_1$ and $p_2$, of radius $r$, with their own velocities (preferably in $(x,y)$ form, but $(m, \theta)$ works too) and masses (unit-less, but same unit) collide in two ...
1
vote
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?
0
votes
1answer
79 views
Combining Conservation Laws ~ Homework Problem Guidance
Problem 8.79 - Combining Conservation Laws
A 5.00-kg chunk of ice is sliding at 12.0 m/s on the floor of an ice-covered valley when it collides with and sticks to another 5.00-kg chunk of ice that is ...
0
votes
1answer
65 views
What is the momentum of these emitted photons?
5 x 10^7 kg of radioactive material emits energy in the form of photons of red light (700 nm). (Note: photons have no mass.)
What is the momentum of each photon?
...
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 ...
3
votes
2answers
313 views
block slides on smooth triangular wedge kept on smooth floor.Find velocity of wedge when block reaches bottom
Find the velocity of the triangular block when the small block reaches the bottom:
Here is what I did:
The final velocity(at the bottom)of the small block of mass m is $\sqrt{2gh}$ along the plane ...
0
votes
1answer
274 views
Kinetic energy in the center of mass
In a collision of a particle
of mass $m_1$ moving with speed $v_1$ with a stationary particle
of mass $m_2$ not all the original kinetic energy can be converted
into heat or internal energy. what ...
2
votes
1answer
407 views
Elastic collision in two dimensions
Suppose a particle with mass $m_1$ and speed $v_{1i}$ undergoes an elastic collision with stationary particle of mass $m_2$. After the collision, particle of mass $m_1$ moves with speed $v_{1f}$ in a ...
0
votes
0answers
81 views
A momentum problem [closed]
A 3.0 kg car A travelling 8.5m/s on a frictionless track collides and sticks on to a stationary 2.0 kg car B.
1
vote
1answer
83 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 ...
0
votes
0answers
26 views
Elastic Collision Between Two Objects [duplicate]
Possible Duplicate:
Elastic Collision And Momentum
I've already asked this question, Elastic Collision And Momentum, but I didn't find the answer particularly helpful--sorry, I don't mean ...
0
votes
1answer
318 views
Elastic Collision And Momentum
The question I am working on is, "Two blocks are free to slide along the friction-less wooden track shown below. The block of mass $m_1 = 4.98~kg$ is released from the position shown, at height $h = ...
0
votes
1answer
61 views
Physics Impulse
This is the problem I am dealing with:
"One of the functions of an automotive air bag is that it lengthens the collision time. Without an air bag, suppose the 100Ns impulse of a collision is taken up ...
1
vote
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 ...
0
votes
1answer
122 views
Momentum And Energy Problem
The information to the question is, "A $59.0~kg$ boy and his $38.0~kg$ sister, both wearing roller blades, face each other at rest. The girl pushes the boy hard, sending him backward with a velocity ...
0
votes
1answer
332 views
Relative Velocity and Momentum
The question is, "A $45.5~kg$ girl is standing on a $140~kg$ plank. Both originally at rest on a frozen lake that constitutes a friction-less, flat surface. The girl begins to walk along the plank at ...
0
votes
1answer
195 views
What is the linear momentum of an inelastic and elastic collision?
The arrows in the figure represent the linear momentum of two balls before they collide. If the collision is perfectly inelastic, find the linear momentum after the collision. If the collision is ...
0
votes
0answers
43 views
What is the momentum of the system in the center of mass frame? [closed]
During a baseball game, a batter approaches the plate. The pitcher hurtles the ball in the direction of the batter at a speed of 85 miles per hour. The batter swings and makes contact with the ball. ...
0
votes
4answers
179 views
Find total energy and momentum of an moving electron in a rest frame
I have an electron moving with speed $u'$ in a frame $S'$ moving with speed $v'$ relative to a rest frame $S$.
How do I find the total energy and momentum of the electron in the rest frame $S$?
I ...
1
vote
3answers
266 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 ...
0
votes
0answers
821 views
Moment of Inertia problem [closed]
I'm revising for my exam and there's this one problem where I can't get the correct answer, so I'd like to know how to solve it. The problem is:
Two boys, each with a mass of 30kg, are sitting ...
0
votes
0answers
248 views
Error Analysis, Change in momentum, Kinetic Energy
If momentum of an object is increased by 10%,then its kinetic energy will be increased by?
Well, I don't need the solution logically by calculating the change in Kinetic Energy etc, but my question ...
1
vote
1answer
687 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 ...
1
vote
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 $m$, ...
-1
votes
2answers
225 views
Newton's Third Law - Action and Reaction on space, what happen with the astronaut? [closed]
This is a question from my homework.
Imagine an astronaut doing a repair in his ship, "parked" somewhere in space where gravity result is zero. As he can not do the repair, gets nervous and throws ...
-3
votes
1answer
135 views
Mathematical question on Collisions [closed]
A 2.5kg ball travelling with a speed of 7.5m/s makes an elastic
collision with another ball of ...
0
votes
1answer
166 views
Momentum question?
The problem:
In a car crash, a passenger with a mass of 82kg is not wearing a
seatbelt. The car is travelling at 45km per hour. What impulse must
the car's airbag provide in order to stop the ...
1
vote
1answer
476 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 ...
3
votes
1answer
397 views
Walter Lewin Lecture 16 - Ball bouncing on wall?
I never did Physics in university and I consider that a mistake so I am correcting that now by teaching myself. To that extent I have been watching the MIT lecture videos by Walter Lewin and I am ...
1
vote
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 ...
2
votes
1answer
227 views
momentum conservation question involving a rocket and a spaceship [closed]
With the engines off a space ship is cruising at a velocity of 230m.s
It fires a rocket straight ahead at the enememy vessel. The mass of the rocket is 1300kg and the mas of the ship (not including ...
