Physics Modern Physics Level: University
AtomThis is another wavefuntion problem where the wave travel through three regions. The first region is before the barrier the second is the barrier and the third is after the barrier. Suppose that U ( sub-0)=0.500 eV and w=2.00 W is the width of the barrier. What fraction of the orginal wave is transmitted if the total energy of the electron is
(a) 0.800 eV
(b) 0.250 eV
(c) 0.100 eV
Explain all issues involved.
Physics Modern Physics Level: University
AtomAt a temperature of 20 degrees celius determine the probability that an electron can occupy a state 0.135 eV above the fermi energy.
Physics Modern Physics Level: University
AtomThis problem deals with the wave funtion and it traveling through a ( step - up) barrier of potential energy. The region before the barrier the region in the barrier and the region after the barrier. Explain how quantum mechanice can allow the wave to exist in all three regions but especially in the region of the potential of height U(sub-o) 0 x w. How is the wave in region 1 ( before barrier) connected to the wave in region 3 ( after barrier)? Explain in detail how to find the probablility ( analytically- that is as a fromula that shows the relations but that you do not solve all the way) that the wave is transmitted through the barrier. Is this allowed in classical physics? Why or why not.
Physics Rotational Mechanics Level: University
TorqueFind the speed of a 20.0 kg mass hanging from a light rope from a massive wheel tha moment of inertia of 100.0 kg m^2 after it has fallen 5.0 m from the orginal level under the wheel. If R=0.20 m what is the mass of the pulley assuming it is a cylinder? How would your answer change if the central axle (of radius 0.05 m ) were essentially massless? Explain clearly what you are doing.
Physics Misc Topic Level: University
Consider a roller coaster ride in a amusement park. The inner loop has a radius of 5.00 m. The top of the ride inside the loop gose 20.00 m above the ground.(a) What is the minimum speed at the top that assures that a car that slides along he track will not fall off the track?
(b) How high up must the car have been to attain this speed?
(c) A sneaky amusement park owner substitutes a spherical car. The spherical rolls without slipping down the incline. What is the minimum height to attain a speed of 7.00 m/s?
Physics Modern Physics Level: University
Dual Nature of Matter and RadiationThe energy gap is 1.1 eV in room temperature silicon.
(a) What is the lowest energy photon that can excite an electron from the valence band into the conduction band? Why is it the lowest? Explain.
(b) What is the photons frequency? Wavelength?
Physics Heat & Thermodynamics Level: University
SpecificheatA small meteorite comprised of iron with mass 1.32 x 10^3 kg enters Earths atmosphere from space and crashes into lake camplain ( a body of fresh water which has a total mass of 8.56 x 10^8 kg). The entry into Earths atmosphere increases the temperature of the meteorite to 3.24 x 10^3 degrees celius just before it comes apart in small pieces and impacts he water at a speed of 3500 m/s above the deepest part of the lake. The temperature of the lake is a chilly 10 degrees celius just before the impact. What is the final temperature of the system of the lake and meteorite? For this purpose assume the lake bottom is a good thermal insulator.
Physics Modern Physics Level: University
Electron DensityIn a doped semiconductor the band gap is 0.078 eV. Compare the proportion of the charge carries in the semiconductor at room temperature and at 300 degrees celius.
Physics Heat & Thermodynamics Level: University
Flow of heatThe air temperature over a lake is -10 degrees celius while the water below the surface of the ice (now 1.00 cm thick is at 4 degrees celius. What is the speed at which the ice layer on the lake thickens ( measured in m/s or some multiple thereof) ? Information you may need: The thermal conductivity of ice is 1.6 w/(mk) the specific heat of ice is 2000J/kg degrees celius) that of water is 4186 J/kg degrees celius) and the latent heat of fusion of water is 334kJ/kg.
Physics Modern Physics Level: University
AtomThe Boron atom is now ionised by removing several electrons such that it can be described as a hydrogen- like boron ion. State how many electrons it now contains and write down the symbol for this ion.
Physics Modern Physics Level: University
RadioactivityAssume initially that the Boron atom created in the rarioactive decay of 4^11 Be is electrically neutral. How many protons how many neutrons and how many electrons does the Boron atom contain?
Physics Modern Physics Level: University
RadioactivityOne isotope of Beryllium 4^11 Be undergoes beta- minus decay with a half-life of around 14 seconds write an equation for the beta-minus decay of a4^11 Be atom showing the symbols for the Boron isotope that is produced and for the other particles that are emitted.
Physics Work,Power & Energy Level: University
Work energy theoremHow much work is done during a 14-hour period by the trees in proud Lake Recreation area in transporting water from their root systems to their leaves (There are 3700 acres in proud Lake an average of 4840 trees per acre, average height of a tree is 44 feet and a typical tree raises 260 gallons of water during the 14-hour period.
b. If this work could be harnessed in the form of electrical energy how many 75 W light bulbs could the proud Lake trees operate during the 14-hour period?
Physics Force & Laws Of Motion Level: University
Force in equilibriumA student has a 75g crystal hanging by a string of negligible mass from the rearview mirror in her car.
a. Determine the angle the string makes with the vertical when she accelerates at a constant rate of .35g ( maybe this is a typo and should be .35 m/s ??)
b. Determine the tension in the string during this acceleration.
c. Construct a free body diagram of the crystal
Physics Work,Power & Energy Level: University
Conservation of EnergyA 12.1 gram bullet is fired horizontally into a 24.0 cm thick wooden fence post at a point 155 cm above the ground with a speed of 430 m/s. The bullet then exits the post striking the ground 3509 cm from the base of the post. Determine the average resisting force exerted by the post on the bullet.
