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.

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.

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?

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.

Discuss the physical principles behind lasers.

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.

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?

Could you please explain thin film interference and the equations for it I just don't get it. Thank You

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.

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.)

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.

As a city planner, you receive complaints from local residents about the safety of nearby roads and streets. One complaint concerns a stop sign at the corner of Pine Street and 1st Street. Residents complain that the speed limit in the area (89 km/h) is too high to allow vehicles to stop in time. Under normal conditions this is not a problem, but when fog rolls in visibility can reduce to only 47 meters. Since fog is a common occurrence in this region, you decide to investigate. The state highway department states that the effective coefficient of friction between a rolling wheel and asphalt ranges between 0.842 and 0.941, whereas the effective coefficient of friction between a skidding (locked) wheel and asphalt ranges between 0.550 and 0.754. Vehicles of all types travel on the road, from small VW bugs with a mass of 595 kg to large trucks with mass 4095 kg. Considering that some drivers will brake properly when slowing down and others will skid to stop, calculate the miminim and maximum braking distance needed to ensure that all vehicles traveling at the posted speed limit can stop before reaching the intersection. Minimu =? Maximum=?Given that the goal is to allow all vehicles to come safely to a stop before reaching the intersection, calculate the maximum desired speed limit. = kmh?.

Now you will need to use your data to calculate velocities and accelerations. Recall that we have discussed average velocity as vavg = Δx/Δt as well as vavg = (vi + vf)/2. We also discussed average acceleration as aavg = Δv/Δt. Using these equations, calculate the instantaneous velocity of your cart at each distance/time data point and the average acceleration between each pair of distance/time data points. When you have completed your calculations, organize your results into a table with four columns: time, position, velocity, and average acceleration.