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5 views

Work done on lifting a water losing bucket

A bucket of mass $m$ is filled with water of mass $M$ from a well of height $h$. But there is a hole in a bucket from which the water escapes at a uniform rate. When water reaches the top till then ...
1
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0answers
19 views

Determining Constant of Motion

On the phase space $\mathbb{R}^4$ consider the Hamiltonian $$H(x_1, x_2, p_1, p_2) = a(p_1^2 + x_1^2) + b(p_2^2 + x_2^2) + c(p_1 p_2 - x_1 x_2)$$ Find a constant of motion by showing that $H$ ...
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1answer
16 views

By what factor a planet travels (in circular orbit) faster than another

Question: It is known that radius of Neptune in a circular orbit around the sun is 30 times greater than that of Earth's. Does Neptune travel faster than earth and by what factor? Attempt: For a ...
2
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2answers
148 views

Energy to reach the moon

I've been stuck on this question for a couple of days now. Given that the potential energy of a 930 kg object on the Earth's surface is -58.7GJ, calculate the minimum energy required for the 930 ...
1
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1answer
25 views

How can I find an error formula for density? [on hold]

$${p} = \frac{4m}{πtd^2}$$ How can I find the error in this formula? I don't know where to begin. I know that I'm looking for the "partial derivative" of density to solve this, but that is a brand ...
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1answer
145 views
+50

What are the general solutions to a hard sphere collision?

Surely someone has found the solutions to the hard sphere collisions (in $n$ dimensions) of two bodies of mass $m_1$ and $m_2$, respectively--that is the resultant velocities (or momenta) of the two ...
-2
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0answers
27 views

Maxwell-Boltzmann speed distribution [on hold]

A container has $10^4$ $N_2$ molecules per $\text{cm}^3$. Assuming that the particles are distinguishable and $$A = \frac NV \left( \frac{m}{2 \pi k \, T} \right)^{3/2}$$ , Tabulate the values of ...
3
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0answers
24 views

Axion Model Field Theory Problem

This is a homework problem for a field theory class dealing with an axion model. Originally, we are given that $$S[a]=\int_Md^4x \frac{1}{2}(\partial_{\mu}a(x))^2$$ has a continuous global ...
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1answer
231 views

Electric field from current without Maxwell's law of induction

A long, straight wire carries a current that decreases linearly with time. What is the direction of the induced electric field outside the wire? I would interpret this as follows: a current ...
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0answers
14 views

How would you construct a linear graph to determine the density of some material? [on hold]

The density $\rho$ of a solid is found by dividing the object's mass by its volume. If the masses and diameters of several coins are given and you are told that each coin has the same thickness and is ...
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0answers
15 views

Comparison of the classical and quantum distribution functions [on hold]

The distribution functions $f_{MB}(E)$, $f_{BE}(E)$ and $f_{FD}(E)$ all have the undetermined constant $A$ (= $\exp(-α)$ ). This may be viewed as a normalization constant, whose value can be found ...
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4answers
363 views

Question about canonical transformation

I was going through my professor's notes about Canonical transformations. He states that a canonical transformation from $(q, p)$ to $(Q, P)$ is one that if which the original coordinates obey ...
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1answer
90 views

Angular Velocity after a frictional impulse

I am modelling 2D physics collision into simulations. In Physics for Game Programmers, Grant Palmer book, the velocity Vn1 after collision is mentioned to be independent of the friction coeff. ...
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3answers
4k views

Factors affecting torque and RPM of a motor

I am not a physics guy, so not even the basic concept of a DC motor is easy for me. My question is as follows: How do these parts of a motor affect its RPM and Torque? I had my research a while ago ...
3
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1answer
89 views

Poles for a particle scattered in a delta potential

I am working on problem a professor gave me to get an idea for the research he does, and have hit a point where I'm having a difficult time seeing where I need to go from where I'm at. I would also ...
0
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0answers
14 views

how do I resolve this velocity into components? [on hold]

my problem is: And this is the diagram I drew to resolve it into its constituent R and theta forces: So I get \begin{align} V_r &= - V \cos \theta \\ V_\theta &= V \sin \theta ...
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0answers
18 views

Michelson-Morley Experiment, Time Dilation, Length Contraction assignment need help [on hold]

I have Physics assignment about Michelson-Morley Experiment, Time Dilation, Length Contraction need help. The question are in the pictures Thanks
2
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2answers
25 views

Loads in decelerating a falling object

I'm new here and haven't looked at physics in any real depth since high school, 8 years. so apologies for any obvious mistakes. I remove trees in confined spaces setting up rigging systems, I am ...
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1answer
75 views

Electromagnetic waves in an antenna

There is a few questions that need to be answered in detail but in an easy way... What does it mean to describe the 'plane of polarisation' of electromagnetic waves? Why will some antenna have rods ...
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1answer
25 views

Calculating change in gravitational potential energy [on hold]

A satellite mass 500kg is elevated from altitude 10000km to altitude 20000km. Radius of earth is 6378km. Mass of earth is 5.97 * 10^24kg. Gravity is given to be 9.81m/s My attempt is using final mgh ...
0
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3answers
67 views

If a body is floating in a static fluid, then the volume of the displaced fluid equal to the volume of the inmerse part of the object (proof)

Suppose an arbitrary body is floating in a static fluid, either totally or partially immersed in it, then the volume of the displaced fluid equal to the volume of the immersed fraction of the object. ...
3
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1answer
43 views

Equation of motion for system of springs

I need to find the equations of motion for the following system. If $x_1$ is $m_1$'s extension and $x_2$ is $m_2$'s, then, I feel like for $m_1$ we just need to consider $x_1$ giving $$m_1 a_1 = ...
2
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1answer
5k views

How do I relate the direction of a compass needle to the direction of a current?

A compass needle is placed above the wire points with its N-pole toward the east. In what direction is the current flowing? If a compass is put underneath the wire, in which direction will ...
1
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1answer
165 views

Ladder Operator killing state

So in my last question, @joshphysics showed me how to prove $K_\pm$ were ladder operators. Now I need to show that there is a lowest state, i.e $$\langle m_0|K_+=K_-|m_0\rangle=0$$ I am not ...
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2answers
1k views

Geometric Structure Factor for Monatomic FCC lattice

I am trying to find the geometric structure factor and my work here is clearly wrong. I will put my wrong answer and then I will throw up the link to wikipedia for the correct answer, because I cannot ...
1
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0answers
17 views

flow through an orifice [on hold]

The surface area of a first orifice with 2 mm diameter is 3 mm$^2$. The surface area of a second orifice is 5 times bigger from the surface area of the first orifice (15 mm$^2$). How much would be ...
1
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0answers
54 views

Two boxes connected by a rope

Two boxes, $A$ and $B$, are connected to each end of a light vertical rope. A constant force of $70.0N$ is applied to box $A$. Starting from rest, box $B$ descends $11.6m$ in $4.40s$ The tension ...
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2answers
490 views

How do I express the interaction energy between two charged spheres?

Consider two identical insulating spheres each with radius $R$ and uniform charge $Q$ through their volume. They are separated from their centers by a distance of $d>2R$. Here is my general ...
0
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2answers
45 views

Projections in Polar coordinate system

I really understand what projections in Cartesian coordinate system, I can imagine this, but I absolutely do not understand projection in polar system. For example, I have a speed, $U$, and I must ...
0
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3answers
103 views

How fast would the Earth need to spin for us to feel weightless?

It's a classic question with many answers all over the Internet, but none here so I figured I'd ask it: How fast would the Earth need to spin for a person (or anything for that matter) to feel ...
1
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1answer
31 views

Finding the acceleration given only an angle

This is one of my homework problems for a College Physics I course: Dana has a sports medal suspended by a long ribbon from her rearview mirror. As she accelerates onto the highway, she notices ...
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2answers
38 views

Derivation of the average Velocity formula with constant acceleration (using calculus)

I have been looking at $$ v_{avg} = \frac{v_{i} + v_{f}}{2}, $$ when the acceleration is constant, where $v_i$ is equal to the initial velocity and $v_f$ is equal to the final velocity. How can ...
0
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1answer
43 views

The forces acting on 2 boxes [on hold]

Consider the following figure: The surface is not friction-less. When the force $F$ is applied on mass A: Is the force the mass A applies on mass B larger, smaller or equal then the Force that B ...
0
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1answer
49 views

Why is the slippage constraint for one moving cylinder and one fixed cylinder $r(\phi - \theta)=R \theta$? [on hold]

Why is the slippage constraint for one moving cylinder and one fixed cylinder $r(\phi - \theta)=R \theta$? Every time I write it down on paper I get the result $r\phi = R \theta$. I am not sure if I ...
2
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1answer
346 views

What defines the adiabatic flame temperature?

What defines the adiabatic flame temperature? In a case I have to solve, I need to describe the combustion of natural gas (Groningen natural gas, to be specific). However, I am having some problems ...
3
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4answers
282 views

If a truck collides with a car, can the truck experience a larger force?

I am confused, here is a question: A large truck and a mini bus both have same velocity V and they collide and stop. The collision lasts for 1 second. A) Which one of the two will experience ...
0
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0answers
97 views

Laplacian and Dirac Delta function

Although I find it mathematically dubious, we said that $$\Delta \frac{1}{r} ~=~ -4\pi \delta^3({\bf r}).$$ Now, I was wondering is there a similar relation to the delta function if we look at ...
3
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0answers
27 views

Reduce density matrix for given eigenfunction [on hold]

My question is about how to find reduce density matrix for partition of given eigenfunction. Full question is just in image.
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0answers
23 views

Calculate depth of cone in water as water is poured inside the cone [on hold]

Consider a cone with radius $r$ and length/height $h$. A water container has volume $V$, and if needed dimension $d(x,y,z)$. This cone is put on the water, and water is slowly poured inside the ...
0
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0answers
23 views

How to calculate the ship resistance caused by water viscosity

If there is a ship going in the sea at 50km/h, and a length of 5m, width of 2m, how do I calculate the ship resistance caused by water viscosity? in other words I want to calculate the drag Force that ...
0
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0answers
37 views

minimum rope stiffness to keep person from touching ground(hooke's law) [on hold]

I thought a lot about this problem (However it's must be very easy ) At first, i would write the statement of problem and then my wrong solution. statement: Find the minimum stiffness of rope,so ...
1
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1answer
47 views

How to find the electric field of a charged tube?

Let's say there is a charged tube(cylinder with no top or bottom) with radius $a$, length $l$ and charge $q$ and a point which is collinear with the centre of the charged tube. Anyway, since we can ...
0
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2answers
28 views

Finding power in series circuit

A resistor of resistance 12 ohms is connected in series with a cell of negligible internal resistance. The power dissipated in the resistor is P. The resistor is replaced with a resistor of resistance ...
0
votes
1answer
44 views

Expectation value of number operator $\hat{n}$

I'm studying for my quantum mechanics test and I've stumbled on this problem. They want the expectation value of $\hat{n}$, $\langle \hat{n} \rangle$, with this given $\psi$ at $t=0$: $$ \lvert ...
0
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1answer
20 views

How do I find the moment of inertia of a regular $n$-gon? [on hold]

Of a regular $n$-gon with radius $R$ and mass $M$. Any hint to solving would also be acceptable. The result I'm looking for is $$I_{CM} = (1/2) MR^2 (1 - (2/3) \sin^2(\pi/n)).$$
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0answers
30 views

Can human body survive a negative acceleration of $ 250m/s^2$ [on hold]

Can the human body can survive a negative acceleration trauma accident because of a sudden stop if the magnitude of the acceleration is less than $250m/s^2$. If you are involved in an automobile ...
-1
votes
0answers
33 views

Please tell me the way to solve the following question [on hold]

Question - Consider a box that is divided into two indentical parts of equal volume. The right half contains a gas of $N$ (=100, 500, 1000) particles and the left half is empty. A small hole is ...
1
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0answers
35 views

Find the field of two infinite strips of width $b$ [on hold]

Q:The two charged strips in the following picture have width $b$, infinite height,and negligible thickness(in the direction perpendicular to the page).Their densities per unit area are $\sigma$ ...
0
votes
1answer
31 views

What are overtones and how do they relate to harmonics?

Problem 43. Two organ pipes, a pipe of fundamental frequency 440 Hz, closed at one end, and a pipe of fundamental frequency 660 Hz, open at both ends, produce overtones. Which choice below ...
0
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0answers
7 views

How to figure out new vector direction after deflection by polar and azimuthal angles [migrated]

I have a direction cosine vector in Cartesian 3D space. The vector starting point is (x0,y0,z0) and direction {i0,j0,k0}. I need to find the new direction cosine vector direction in the Cartesian 3D ...