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# problems in Quantum Mechanics

1. show that the commutator obeys: [A,B] = -[B,A] [A,B+C]=[A,B] + [A,C] [A,BC]=[A,B]C+B[A,C] [A,[B,C]]+[B,[C,A]]+[C,[A,B]]=0 Given the fundamental commutator relation between momentum and position [x,p] = ih show that: a. [x^n,p] = ihn*x^(n-1) b. [x,p^n] = ihn*p^(n-1) c. show that if f(x) can be expanded in polyno

Elastic and inelastic collision of two objects with arbitrary mass

An object A moving with velocity V collides with a stationary object B. After the Collision, A is moving with velocity (1/2)V and B with velocity (3/2)V. Find the ratio of their masses. If, instead of bouncing apart, the two bodies stick together after the collision, with what velocity would they then move?

Magnetism - Why is a piece if iron attracted to either pole of a magnet? The magnetic poles of the earth are called geomagnetic poles. Is the north geomagnetic pole a north magnetic pole or a south magnetic pole? ...

Questions 19 Why is a piece if iron attracted to either pole of a magnet? Question 20 The magnetic poles of the earth are called geomagnetic poles. Is the north geomagnetic pole a north magnetic pole or a south magnetic pole? Question 29 When a wire loop is rotated in a magnetic field, the direction of the curren

Physics of a jump

What is the physics behind a jump, for example - snowboard jump, skateboard jump, kite boarding jump, and bike jump?

Electro-Magnetic Induction

See the attached file. A rectangular conducting loop of width w, height h, and resistance R is mounted vertically on a nonconducting cart (see attachment). The cart is placed on the inclined portion of a track and released from rest at position P1 at a height y above the horizontal portion of the track. It rolls with negligib

Consider a two level system (such as the orientation of the magnetic moments of protons in a magnetic field, e.g. NMR). Let the spacing between the two levels be delta that is, the lower level has an energy of 0 and the other an energy of delta. Evaluate the following quantities in terms of delta and T. a) the partition function b) the internal energy c) the entropy In the limit of large T, does the system in the previous problem conform with the equipartition principle? Should it?

Consider a two level system (such as the orientation of the magnetic moments of protons in a magnetic field, e.g. NMR). Let the spacing between the two levels be delta that is, the lower level has an energy of 0 and the other an energy of delta. Evaluate the following quantities in terms of delta and T. a) the partition functio

Solar Power: Photovoltaics

Need a breakdown of solar power and how it works. Need an explanation that is focused on how solar power can be harnessed in constructing a solar powered car.

Problems on rigid body dynamics.

Please solve problems 6/140 and 6/127 only. Refer attachment for fig. Problem 6/140 : The sheave of 400 mm radius has a mass of 50 kg and a radius of gyration of 300 mm. The sheave and its 100 kg load are suspended by the cable and the spring which has a stiffness of 1.5 kN/m. If the system is released from rest with the spri

Wavefunctions and expectation values

For a particle in a 1-dimensional box confined between 0<x<a , the initial state of a particle is given by phi = phi_1 + 3phi_2 + 2phi_3 (all phi's are functions of x). a) Normalize this wave function. b) If no energy measurements are made what is the expectation value of energy of this state at a later time t? c)

Energy of a Thrill Seeking Cat

A thrill-seeking cat with mass 4.00 (rm kg) is attached by a harness to an ideal spring of negligible mass and oscillates vertically in SHM. The amplitude is 0.050 (rm m), and at the highest point of the motion the spring has its natural unstretched length. Calculate the elastic potential energy of the spring (take it to be zero

A girl springs from a trampoline with an initial upward velocity. At a given height above the trampoline, the girl grabs a box. What is the maximum height that the girl (with box) reaches?

A girl of mass m1= 60 kilograms springs from a trampoline with an initial upward velocity of v1= 8.0 meters per second. At height h= 2.0 meters above the trampoline, the girl grabs a box of mass m2 = 15 kilograms. For this problem, use g= 9.8 meters per second per second for the magnitude of the acceleration due to gravity. W

Elastic Collisions Calculation

That neighbor's pesky kid now has new missiles that make elastic collisions- He insists on throwing 25.0 g rocks at your new 2.25 kg light fixture hanging by a 26.0 cm wire from the ceiling of your porch. If each rock strikes the fixture traveling at 10.0 m/s, how high will the light fixture go after it is hit by one of these

Microstates and macrostates for an assembly of three particles

1. Enumerate all the microstates and macrostates for an assembly of three particles fixed in position with levels, 0, e, 2e, 3e, and a total energy of 3e. What is the least and what is the most probable distribution of energy? What is the average distribution of energy? 2. 1200 distinguishable particles are to be distributed

The mass of an electron is 9.11x10to the minus31 kg.

1. The mass of an electron is 9.11x10^-31 kg. The mass of one (negative) coulomb of electron (in kilograms) is equal to? 2. If a charge of 8.4 microcoloumbs is evenly distributed around a ring of radius 0.31m, the charge per unit length (in micro c/m) will be? 3. An engine takes in 4.7 calories of heat and discharges 3.5 c

heat lost from the steam pipe

2. A steam pipe is covered with 1.50cm thick insulating material of thermal conductivity 0.200 cal s"1 cm"1 °C"1. How much energy is lost per second when the steam is at 200°C and the surrounding air is at 20.0°C? The pipe has a circumference of 800cm and a length of 50.0m. Neglect losses through the ends of the pipe.

Superball Collides With a Table. To determine change in momentum.

As shown in the figure (see attachment), a superball with mass m equal to 50 grams is dropped from a height of h1= 1.5 m. It collides with a table, then bounces up to a height of h2= 1.0 m. The duration of the collision (the time during which the superball is in contact with the table) is tc= 15 ms. In this problem, take the

difference between the tensions in the string

A ball of mass m is attached to a string of length L. It is being swung in a vertical circle with enough speed so that the string remains taut throughout the ball's motion. Assume that the ball travels freely in this vertical circle with negligible loss of total mechanical energy. At the top and bottom of the vertical circle, th

Angular Momentum

Please see attached. 1. The two spheres of equal mass m are able to slide along the rotating horizontal black rod. If they are initially latched in position a distance r from the axis of rotation with the assembly rotating freely with an angular velocity of Wo. Determine the new angular velocity Wf after the spheres are rele

Question on the Electromagnetic Spectrum for an elementary Astrophysics Course

Q. On a cold winter day, your employer sends you out to make some photographs of an inhabited house that can be used to determine where the house has poor heat-insulation. He offers you to take one of four tools. Which one do you pick: a radio telescope, an infrared camera, an off-the-shelf digital camera, or an UV camera? J

Two problems on capacitors.

1. A controller on an electronic arcade game consists of a variable resistor connected across the plates of a 0.22 micro Farad capacitor. The capacitor is charged to 5.00V, then discharged through the resistor. The time for the potential difference across the plates to decrease to 0.800V is measured by a clock inside the game

the infinite quantum well

A one-dimensional quantum well of width 19 nm is created, and measurements show that the energy difference between the ground state and the first excited state is 0.19 eV. What is the e&#64256;ective mass of the electron in the well? Answer in units of kg.

Wave Mechanics

Part a Consider an electron in an infinite well of width 0.03 nm. Given : 1eV = 1.60218 × 10^-19 J hbar = 1.05457 × 10^-34 J s , What is the ground-state energy of the electron, in electron volts? Answer in units of keV. Part b What is the energy of the first excited state? Answer in units of keV.

Magnetic energy of solar flare

The problem reads as: "The magnetic field permeating a region of space represents stored energy. This energy is often quantified in terms of its density (magnetic energy per unit volume) given by B^2/(2*u) where u=4*pi X 10^(-7). Suppose an "X2" flare occurs within a volume of 10^12 km3 over a sunspot pair initially permeate