Discuss the dark energy. Give reasons for your answer and list the pros and cons of your choice.
In: Physics
For an internal spring force collision, what do you think would be the effext of system momentum if you hit the trigger at a slight angle instead of straight down? Explain why striking angle makes a difference (in terms of internal and external forces)
In: Physics
In this simulation, you can examine the magnetic field created by the current in a solenoid, which is a cylindrical coil of wire. Instead of using a spiral-shaped coil, the simulation approximates the coil with a stack of seven single loops. The plane of each loop is parallel to the x-z plane, with a radius of either 60 cm or 25 cm, and the displayed field is in the x-y plane.
The parallel-plate capacitor is the standard way to create a uniform electric field, while a current-carrying solenoid is a great way to create a uniform magnetic field, although the electric field is only perfectly uniform in the ideal case when the plates are infinitely large and the magnetic field is only perfectly uniform in the ideal case when the solenoid is made from closely packed loops that extend to infinity in the direction parallel to the axis of the solenoid.
(a) Which of the following statements correctly compare the ideal parallel-plate capacitor to the ideal solenoid? Select all that apply.
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In the ideal capacitor changing the distance between the plates does not affect the electric field. In the ideal solenoid changing the radius of the solenoid does not affect the magnetic field. |
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In both ideal devices the fields are uniform inside the devices and zero outside. |
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A charged particle launched into the uniform field between the plates of the parallel-plate capacitor will follow a parabolic path. The same is true for a charged particle launched into the uniform magnetic field inside the solenoid. |
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Doubling the magnitude of the charge on each plate of the ideal capacitor doubles the electric field. Doubling the current in each loop of the solenoid doubles the magnetic field. |
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The electric field in the capacitor is produced by static charges, while the magnetic field in the solenoid is produced by moving charges. |
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The direction of the uniform electric field in the capacitor is parallel to the plates making up the capacitor, while the direction of the uniform magnetic field is parallel to the axis of the solenoid. b) Which of the following statements correctly describe what happens with the non-ideal solenoid shown in the simulation? Select all that apply.
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A stellar object that is at a great distance emits a stream of
matter at velocity v towards an observer obliquely, forming an
angle θ with the observation line. For the observer the jet appears
to have been emitted laterally at speed V.
Show that for certain angles the speed measured by the observer may
exceed the speed of light.
V = sin θ (1 / v - cos θ) −1
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To explore the physics of freefall, a curious student climbs to the top of the Las Vegas-version of the Leaning Tower of Pisa (to be built in the style of the Las Vegas-version of the Eiffel Tower, the Statue of Liberty, …) with two identical cannonballs and conducts a series of experiments. Part A) The student drops one cannonball, and exactly 1.0 s later drops the other cannonball from the same height. What is the time interval between the first cannonball striking the ground and the second cannonball striking the ground? Part B) The student drops one cannonball, and after it has fallen exactly 1.0 m drops the other cannonball from the same initial height. What is the distance between the cannonballs when the first cannonball strikes the ground? Part C) The student throws one cannonball directly upward at 5.0 m/s and simultaneously throws the other cannonball directly downward at 5.0 m/s. (This requires great dexterity, but the student has been practicing this maneuver for several months.) What is the difference in speed between the cannonballs when each ball strikes the ground?
Answer Choices: Less than 1.0 m 1.0 m Greater than 1.0 m Cannot be determined
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how do you chose the energy range of radiating particles/phonons to study the structure of a lattice?
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show how to solve the integral of density of state from 0 to debye frequency and explain the solution
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Make a side by side comparison for the electric potential and the vector potential. Compare them according to: a) Redundancies in their definitions
b) How they can be found from the sources c) How they can be used, if known, to find the magnetic and electric fields d) The matching/interface conditions they satisfy
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In 1-D, the finite square well always has at least one bound state, no matter how shallow the well is. In 3-D, a finite-depth well doesn't always have a bound state.find bound states
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A 0.70-m aluminum bar is held with its length parallel to the east-west direction and dropped from a bridge. Just before the bar hits the river below, its speed is 29 m/s, and the emf induced across its length is 7.0 x 10-4 V. Assuming the horizontal component of the Earth's magnetic field at the location of the bar points directly north, (a) determine the magnitude of the horizontal component of the Earth's magnetic field, and (b) state whether the east end or the west end of the bar is positive.
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Discuss the relationship between storage modulus, yield stress and cohesive energy density? What can you predict about the stability of emulsion with respect to cohesive energy density? (Answer should be few sentences or short paragraph long)
In: Physics
Q1.An n-type silicon wafer undergoes a pre-deposition diffusion process with a constant surface concentration of boride gas; the resulting concentration of boron in silicon at the surface is estimated to be 1x10^18 atoms cm-3 . The background concentration of trace boron atoms in the silicon wafer is estimated to be 1x10^14 cm-3 .(A) Estimate the depth of the p-n junction below the surface when the background doping concentration of the n-type impurity is 3.45 x10^16 cm-3 ; assume the diffusion process proceeds for 10 minutes and has a diffusion parameter given by 10-12 cm2 s -1 .
(B) Estimate the number of boron atoms (per cm2 ) introduced in this thin surface layer following the predeposition step.
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Consider 10 moles of an ideal polyatomic gas in a container with a frictionless piston. The initial pressure is 105 kPascals and initial volume is .3 m3. The gas is isobarically compressed to .1 m3. Determine the resulting change in entropy of the environment. (assume the temperature of the environment is a constant 28 Celsius)
Group of answer choices
a) +453.6 J/K
b) +426.4 J/K
c) +313.8 J/K
d) +349.2 J/K
e) +376.4 J/K
In: Physics
Liquid 1: Water (density: 1g/cm3)
Water displaced = 156 mL
mass of object was found to be 156 g
Liquid 2: Saltwater (density: 1.02 g/cm3)
water displaced: 158.4 mL
Mass of object was found to be 161.568 g
Use what you know about Archimedes’ Principle: specifically the equations and , where the wsubscript refers to the liquid the object floats on and the o subscript refers to the object itself. Derive a formula that relates the densities of the object and the fluid it floats on, as well as the depth that the object submerges in water relative to its height. That is, find how the ratios of the object’s and water’s densities are relate to how much of the object is submerged in the water. Since the object floats, we will know that the whole object cannot be submerged underwater. Write out the formula below and find the density of the object.
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30 grams of ice at -5 Celsius melt while being left at room temperature of 28 Celsius. After melting its temperature rises to 28 Celsius. Determine the total change of entropy of the ice.
[Cice = .5 cal/g.C, Lf = 79.6 cal/gram] 1 calorie = 4.184 J
Group of answer choices
a) 53.11 J/K
b) 34.68 J/K
c) 38.27 J/K
d) 44.22 J/K
e) 49.97 J/K
In: Physics