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# Energy

### Work Function of a Material: Example Problem

Red light of wavelength 670 nm produces photoelectrons from a certain photoemissive material. Green light of wavelength 513 nm produces photoelectrons from the same material with 1.68 times the maximum kinetic energy. What is the material's work function?

### Accelerating Electron

Part 1 Electrons are accelerated from rest through a potential difference of 253700 V. What is the final speed predicted classically? Part 2 What is the final speed predicted relativistically?

### Solar Collector: Determine the smallest collector size that will provide needed energy

A typical home may require a total of 2.17E+3 kW*hr of energy per month. Suppose you would like to obtain this energy from sunlight, which has an average daylight intensity of 1.13E+3 W/m2. Assuming that sunlight is available 8.10 hr per day, 26 days per month (accounting for cloudy days), and that you have a way to store energy

### Calculate density and pressure: Public utilities example

Much work has been done on the large scale storage of energy in inductors for public utilities. One author proposes a huge underground cryogenized inductor that would operate at a field of 14 teslas. a. Calculate the energy density in (kilowatt-hours)/meter b. Calculate the magnetic pressure in atmospheres, (1 atm = 10^

### Kinetic Energy a Ball Acquires from the Bat

A baseball bat strikes a ball with an average force of 2.0 x 104 Newtons. If the bat stays in contact with the ball for a distance of 5.0 x 10-3 meter, what kinetic energy will the ball acquire from the bat?

### Determine the smallest size that will provide needed energy

A typical home may require a total of 2.19E+3 kW*hr of energy per month. Suppose you would like to obtain this energy from sunlight, which has an average daylight intensity of 1.03E+3 W/m2. Assuming that sunlight is available 8.03 hr per day, 24 days per month (accounting for cloudy days), and that you have a way to store energy

### Determine smallest Solar Collector size for needed Energy

A typical home may require a total of 2.19E+3 kW*hr of energy per month. Suppose you would like to obtain this energy from sunlight, which has an average daylight intensity of 1.03E+3 W/m2. Assuming that sunlight is available 8.03 hr per day, 24 days per month (accounting for cloudy days), and that you have a way to store energy

### Angular Velocity, Fractional Loss, Kinetic Energy and Minimum Value

See attached file. A uniform solid cube of edge 2a is sliding with velocity v on a smooth horizontal table when its leading edge is suddenly brought to rest by a small ridge on the table. Which dynamical variables are conserved (a) before impact, (b) during impact, and (c) after impact? Find the angular velocity immediately a

### Electromagnetic Induction: Propel an Artificial Satellite

A natural satellite whose diameter is 10^4 meters moves at velocity of 1 km/s in the direction normal to the magnetic field of a planet in a region where B=10^-7 Tesla. The satellite has appreciable conductivity. d) Someone suggests that this current could provide power for an artificial satellite traveling in the same dire

### Waves and Atoms

Please show all work and provide justification for answers. 1. Waves show the phenomena of reflection, diffraction, refraction, interference, and absorption. Associate at least one or two of these with each of the following. a. You see a mirage. b. You hear someone whispering just around the corner in the next room.

### Heat Transfer Example Problems

The answers are given, but please provide solutions for these questions. Heat Transfer Problems 1. How much heat is conducted in 1.0h through an iron plate 2.0cm thick and the 1,000cm2 in area, the temperatures of the two sides being kept at 0 and 20°C? Answer = 4.0 x 106 cal 2. Compute the heat conducted per hour thr

### Mass-spring system, clock pendulum, submarine sonar echo

1. A mass - spring system in SHM in the horizontal direction. If the mass is 0.25 kg, the spring constant is 12 N/m, and the amplitude is 15 cm, (a) what is the maximum speed of the mass, and (b) where does this occur? (c) What is the speed at half amplitude position? 2. A clock uses a pendulum that is 75 cm long. The clock i

### Mass-spring system, pendulum, oscillator frequency, sound pulses, harmonics

Severe Mental Disorders This question seems to basically be asking for your opinion, so I will try to give you a few ideas about mental disorders that you can expand on. Throughout history, "normal" people who do not have mental disorders have always seemed to be scared or frightened of people who do suffer from mental d

### Netwons Laws

A 31.0 kg gun is resting on a frictionless surface. The gun fires a 50.0 g bullet with a muzzle velocity of 306.0 m/s. Assume that air resistance is negligible. (a) Calculate the momenta of the bullet and the gun after the gun is fired. kg·m/s (bullet) kg·m/s (gun) (b) Calculate the kinetic energy of both the bulle

### Simple Harmonic Motion for a Resting Block

A 1.73 x 10-2-kg block is resting on a horizontal frictionless surface and is attached to a horizontal spring whose spring constant is 123 N/m. The block is shoved parallel to the spring axis and is given an initial speed of 8.69 m/s, while the spring is initially unstrained. What is the amplitude of the resulting simple harmoni

### Determining Inertia and Rotational Kinetic Energy

A helicopter has two blades (see figure), each of which has a mass of 220 kg and can be approximated as a thin rod of length 6.7 m. The blades are rotating at an angular speed of 55 rad/s. (a) What is the total moment of inertia of the two blades about the axis of rotation? (b) Determine the rotational kinetic energy of the spin

### Electric Field Energy: Energy due to a Dipole Outside Sphere

Consider an imaginary sphere of radius a centered on a dipole of moment p. Show that the electric energy associated with the region of space outside the sphere is: w= (p^2/12*pi*epsilon sub 0*a^3) by integrating the energy density from r=a to r=infinity.

### Brick slides down an incline speed

See attached diagram. The diagrams in Figure 9-13 show a brick weighing 24.8 N being released from rest on a 1.00 m frictionless plane, inclined at an angle of 30.0°. The brick slides down the incline and strikes a second brick weighing 37.4 N. Figure 9-13 (a) Calculate the speed of the first brick at the bottom of the i

### Four problems on electrostatics

#1 A charge of -3.00 nC and a charge of -5.80 nC are seperated by a distance of 50.0 cm. Find the position at which a third charge of +7.50 nC can be placed so that the net electrostatic force on it is zero. #2. A 7.5-nC charge is located 1.8 m from a 4.2-nC charge. Find the magnitude of the electrostatic force that one charg

### Quantum Mechanics One Dimensional Potential

An electron is trapped in an infinite one-dimensional potential well of width 0.132 nm. The electron is in the n=10 state. A) What is energy of the electron? B) What is the uncertainty in its momentum?

### Finite square well

See attache file for full description. The particle is in a finite square well and we are required to show that if the potential approaches infinity we regain the energy levels of infinite well. Find the condition for solution and show that there is always an even solution and there is no odd solution unless. V > h^2*Pi/8ma^

### One dimensional Quantum Mechanics problems

1, Show that for any normalized |u> , the inequality E0 <= <u|H|u> holds, where E0 is teh lowest energy eigenvalue. Prove the following theorem: Every attractive potential in one dimension has at least one bound state. 2. Consider the potential V = -aV0 * delta(x) Show that it admits a bound state of energy E = -ma

### Vibrating and Oscillating String

Find the total energy of a vibrating string of length L, fixed at both ends, oscillating in its n'th characteristic mode with and amplitude A. The tension in the string is T and its total mass is M. Hint - consider the integrated kinetic energy at the instant when the string is straight so that it has no stored potential ener

### Final Velocity of Block and Temperature Rises

Q.4. a- A 1-kg iron block is to be accelerated through a process that supplies it with 1 KJ of energy. Assuming all this energy appears as kinetic, what is the final velocity of the block? b- If the heat capacity of iron is 25.10 J/(mol K) and the molecular weight of iron is 55.85, how large a temperature rise would result f

### Sun-Spot Black Temperature

1. Why is a Sun-spot black although its temperature is over 4000 C ? 2. If the mass of the Sun decreases because of nuclear fusion, why don't we see the Sun decreasing in size ? 3. Why do space-craft not melt in the heat of the million degree corona?

### Impulse, momentum conservation, potential energy

1. Define the term impulse. 2. Using the principle of momentum conservation, explain what happens when a moving billiard ball collides with a stationary ball (cue ball hitting the eight ball). 3. Explain the difference between energy and power and how they are related to work. Give examples of each). 4. A 1000 kilogra

### Kinetic Energy and Potential Energy.

In this simulation, an object traverses the "hills and valleys" of a frictionless roller coaster in the realm of zero air resistance. You will be asked to find measurements and make calculations concerning total mechanical energy and whether it is conserved. Then you will then make some changes to the global air resistance for

### Total Momentum Systems

A 2.3-kg cart is rolling across a frictionless, horizontal track toward a 1.5-kg cart that is held initially at rest. The carts are loaded with strong magnets that cause them to attract one another. Thus, the speed of each cart increases. At a sertain instant before the carts collide, the first cart's velocity is +4.5m/s, and th

### 15 Multiple Choice Questions on Modern Physics - Photons And Photoelectric Effect (Fully Solved and Explained)

1.The wavelength of a photon is 7 x10^-7 m. Calculate the frequency of the photon. Also calculate the energy of the photon in Joules and eV a)4.285 x 10^15 Hertz, 2.84 x 10^-19 Joules, 2.36 eV b)4.285 x 10^15 Hertz, 2.84 x 10^-19 Joules, 1.77 eV c)3.236 x 10^15 Hertz, 3.42 x 10^-19 Joules, 2.36 eV d)3.236 x 10^15 Hertz, 3.4

### A block slides down a large globe starting from the top. To determine the height at which the block leaves the globe and its speed at that moment.

A large globe, with a radius of about 5 m, was built in Italy between 1982 and 1987. Imagine that such a globe has a radius R and a frictionless surface. A small block of mass m slides starts from rest at the very top of the globe and slides along the surface of the globe. The block leaves the surface of the globe when it reache