Which of the statements regarding this situation are true? Select all that apply.
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Two ice skaters, Daniel (mass 65.0kg ) and Rebecca (mass 45.0kg ), are practicing. Daniel stops to tie his shoelace and, while at rest, is struck by Rebecca, who is moving at 13.0m/s before she collides with him. After the collision, Rebecca has a velocity of magnitude 8.00m/s at an angle of 53.1? from her initial direction. Both skaters move on the frictionless, horizontal surface of the rink.
Part A
What is the magnitude of Daniel's velocity after the collision?
Part B
What is the direction of Daniel's velocity after the collision?
Part C
What is the change in total kinetic energy of the two skaters as a result of the collision?
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A cyclist turns her bicycle upside down to repair it. She then notices that the front wheel is executing a slow, small amplitude, back-and-forth rotational motion with period 12 s. Treating the wheel as a thin ring of mass 600 g and radius 30 cm, whose only irregularity is the tire valve stem, determine the mass of the valve stem.
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A 50·g ice cube (at 0°C) is placed in an insulated cup with 250·g of water which is at 46°C. The latent heat of fusion for ice is 80·cal/g and the specific heat of water is 1.0·cal/g/°C.
(a) How much heat will the ice have to absorb from the water to completely melt (and turn into 0°C water)? ___ cal.
(b) Find the temperature of the 250·g of water initially at 46°C after it loses the heat required to melt the ice.? ___ °C.
(c) How much heat will the 250·g of warmer water have to transfer to the cooler water in order for its temperature to drop by 1°C? ____ cal.
(d) How much will the temperature of the 50·g of cooler water rise when it gains the heat lost by the warmer water as it cools by 1°C? ____°C.
(e) Using your results from the two previous parts, continue to follow the process of heat transfer between the warmer and cooler water until they come to equilibrium. At what temperature will they reach thermal equilibrium? _____°C.
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Select all that are correct: 14. Brown Dwarfs: a. are plotted at the extreme lower left-hand corner of an HR diagram. b. are all main sequence stars. c. are actually Òfailed stars.Ó d. include Jupiter. e. are all thought to be the final evolutionary state of the lowest mass Main Sequence stars. 20. During post main sequence evolution: a. elements heavier than helium can be produced. b. the remaining lifetime is much shorter than the same star's main sequence lifetime had been. c. all stars will become extreme Population I stars in their surface spectrum. d. some stars still continue to burn hydrogen in their innermost cores. e. all stars tend to increase their masses slightly.
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a box contains two halves separated by a partition. Initially, there are 3 ideal gas molecules in the left half, and a vacuum in the right half. The partiition is then removed so the gas goes through a "free expansion" so that the speeds of the molecules are unaffected. In the final state, each molecule has probability of 1/2 of being in the left half of the box and probability of 1/2 being in the right half od the box. Because each of the 3 molecules now has twice as many possible positions than before, the number of microstates of the system has increased by a factor of 2x2x2=2^3. Determine the change in entropy of the system as a result of removing the partition. (Note: We can only calculate the change in entropy of the system but not the initial and final entropy values without knowing more information) What is the probability that all three molecules will simultanesouly be in the left half of the box?
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1. As the frequency goes to zero, to what value does the phase constant approach? What is expected?
2. To what value should the phase constant approach at very high (compared to the resonant frequency)?
3. Does the current lead or lag the applied voltage at very high frequency?
4. For driving frequencies below the resonant frequency, which is larger, the capacitive reactance or the inductive reactance?
5. Can any of the amplitudes VR, VL, or Vc be larger than the amplitude of the source emf E? Why or why not? One might consider an RLC phasor diagram to answer this question.
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Discuss the physical principles behind lasers.
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A 5kg object starts off at ? = 0 travelling at ?x= +10m/s . During its motion, it is subject to a position-dependent force given by:
?net(?) = +480 + 2 ≤ ? ≤ 4,
−120? + 4 ≤ ? ≤ 6,
0 ??ℎ??????
When the object arrives at ? = +4? (parts a-b):
a. Calculate the work done on the object.
b. Calculate the speed of the object.
When the object arrives at ? = +8? (parts c-e):
c. Calculate the total net work done on the object up until this point.
d. Calculate the speed of the object
e. Suppose the net force between +4 ≤ ? ≤ 6 is entirely due to a non-conservative force (and all other forces are
conservative), how much total mechanical energy is lost to the environment during the whole trip?
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A spherical raindrop falling through mist builds up mass. The mass accumlates at a rate proportional to its cross-sectional area and invers;ey proportional to its velocity, that is, dm/dt=k?r2/v, where r is the radius of the raindrop at a given time and v is the downard speed at the same time.Assuming the density P of the rain drop is a constant. Ignoring the resistance do to the fog and the air, calculate the instaneous acceleration of the raindrop as a function of v,r,P,g and k.
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Explain charging by contact. How is the charge of the charging object related to the charge of the thing being charged once the charging is complete?
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Could you please explain thin film interference and the equations for it I just don't get it. Thank You
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Calculate the mass of the sun from the radius of the earth's orbit (1.50×1011 m), the earth's period in its orbit, and the gravitational constant G.
What is the density of the sun ? (The sun's radius is 6.96×108 m). Notice how it compares with the density of the earth.
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An electron is accelerated to a speed where its total energy is 226 times larger than its rest energy.
PART 1
How many times is the kinetic energy of the electron larger than its rest energy?
PART 2
What is the kinetic energy of the electron?
PART 3
What is the speed of the electron in terms of the speed of
light?
(In this part of the problem you have to enter your answer with a
precision of seven or eight digits!)
PART 4
What is the momentum of the electron measured in MeV/c units? (Enter only a number without the MeV/c unit.)
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A 7 μC charge is at the origin. Another particle, placed at x = 0.2m feels of force of 11N in the negative x-direction.
a) Find the value of the unknown charge.
b) Find the electric field midway between these two charges.
c) Find the potential midway between these two charges.
d) Find the potential energy of this pair of charges.
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