An AM radio station has a frequency of 1000 kHz; it uses two identical antennas at the

same elevation, 150 m apart.

a) In what direction is the intensity maximum, considering points in a horizontal plane?

b) Calling the intensity in (a) I₀, determine in terms of I₀ the intensity in directions making

angles of 30^o, 45^o, 60^o and 90^o to the direction of maximum intensity.

77 kW is to arrive at a town over two 0.140 ? lines. Estimate how much power is saved if the voltage is stepped up from 240 V to 2400 V and then down again, rather than simply transmitting at 240 V . Assume the transformers are each 99% efficient.

For each answer, please briefly explain the reasoning behind the answer.

1. True or False: For heat pumps, wcycle, irreversible > wcycle, reversible

2. True or False: All pure substances must have S = 0 at T = 0 K.

3. True or False: The maximum theoretical efficiency of a reversible heat engine will decrease if the working substance is a real gas instead of an ideal gas.

4. A reversible process is carried out on an ideal gas NOT under constant pressure conditions. Given that for this process ΔS > 0 and ΔH = 0,

a. the system absorbs heat and expands during the process.

b. the system absorbs heat and contracts during the process.

c. the system loses heat and expands during the process.

d. the system loses heat and contracts during the process.

e. cannot be determined from the information given.

An infinitely long line of charge has a linear charge density of 5.50×10⁻¹² C/m . A proton is at distance 15.0 cm from the line and is moving directly toward the line with speed 1100 m/s .

How close does the proton get to the line of charge?

Express your answer in meters.

A red car and a blue car are driving in the same direction on the interstate. The red car

is travelling at 25 m/s, while the blue car is travelling at 35 m/s. The driver of the blue

car is not paying attention and rear-ends the red car. The red car has a mass of 2,000

kg while the blue car is only 1,000 kg.

a. Prior to the collision, what is the value of the center of mass kinetic energy?

b. In order for this collision to be isolated, what is the maximum amount of energy

that can be converted to other forms during the collision? What percentage of

the initial kinetic energy does this represent?

c. If the system loses 40% of its kinetic energy in the collision, is the system

isolated? Why or why not?

d. Prior to the collision, how fast and in what direction would you need to be

travelling in order for the system to appear to have zero momentum?

e. Regardless of your answer to part (c), assume now that the two vehicles form

an isolated system. If they cars stick together, how fast will they be moving?

f. What minimum amount of kinetic energy must be conserved in order for this

system to be isolated?

4.81e+20 electrons pass through a point in an electrical circuit every 4.96 seconds.
(a) 2080 C of charge pass through that point in how many minutes?
(b) The current though that point is ______ A.
(c) If the resistance of the circuit is 29.3 ? across this leg of the circuit, the voltage across this leg of the circuit is _______ V.

Object A, which has been charged to + 16 nC , is at the origin. Object B, which has been charged to − 22 nC , is at

(x,y)=(0.0cm,2.0cm)What is the magnitude of the electric force on object

A?

Express your answer using two significant figures.

Part B

What is the magnitude of the electric force on object B?

Part C

What is the direction of the electric force on object A?

Part D

What is the direction of the electric force on object B?

Scientists want to place a 4 × 10³ kg satellite in orbit around Mars. They plan to have the satellite orbit a distance equal to 2.3 times the radius of Mars above the surface of the planet. Here is some information that will help solve this problem:

m_mars = 6.4191 x 10²³ kg
r_mars = 3.397 x 10⁶ m
G = 6.67428 x 10^-11 N-m²/kg²

1)

What is the force of attraction between Mars and the satellite?

2)

What speed should the satellite have to be in a perfectly circular orbit?

3)

How much time does it take the satellite to complete one revolution?

4)

What should the radius of the orbit be (measured from the center of Mars), if we want the satellite to take 8 times longer to complete one full revolution of its orbit?

A monochromatic light source emits 164 W of average electromagnetic power uniformly in all directions. The speed of light is 3 � 10^8 m/s. Calculate the average electric-field energy density 4 m from the source. Answer in units of J/m3 . (u_E=1/2 E₀E²)

Calculate the average magnetic-field energy density at the same distance from the source. u_E=1/2 E₀(cB)²

Find the wave intensity at this location.

What is the pressure exerted by the light on a mirror located at the same distance from the source, assuming normal incidence and total reflection?

You MUST show all the diagrams, formulas, substitutions, calculations, results, and unit to receive the whole credit for each problem.

3-  

a) What is the difference between a mechanical wave and an electromagnetic wave? In complete sentences  

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b) Give one example of each:

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c)What is the difference between a longitudinal and transverse wave? In complete sentences.

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d) Give one example of each:

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You and your team get a distress call from another ship indicating that there has been an explosion and their propulsion and navigation systems are now off line. A large piece of their ship has been jettisoned into space, and their life support systems are failing. They need help as soon as possible. You try to track them, but are only able to pick up the piece of the craft that had been projected away from them in the explosion. You look up the make and model of their ship, a Galaxy Explorer 5000 (GE 5000), which has a total mass of 52000 kg. The piece heading in your direction is the ship’s storage module, and has a mass of 9000 kg.

The GE 5000 was at rest with respect to your ship at the time of the explosion.
(a) Assuming you received the distress call 20 minutes before the jettisoned storage module passed by your ship at a speed of 630 m/s, what is the speed of the damaged craft?
(b) How far away is the Galaxy Explorer 5000 when its storage module passes by?
(c) In which direction, and how fast must you go, in order to catch up with the GE 5000 before its life support systems fail. (The crew had 80 minutes of life support left when they made the distress call, so you have 60 minutes to get to them.)

A. Consider two concentric spherical structures of radius r1 and r2 such that r1 < r2 and full load Q and -2Q respectively. Calculate the magnitude of the field on ́ectrico in all three regions, i.e. within the smaller sphere, between the spheres and outside the sphere of the larger radius.
Where does the electric field point to for this system?

(no matter what material these concentric spherical are made of)

B. Two cylindrical coaxial shells with radius r1 and r2 such that r1 < r2 and with linear charge density λ and -λ. Calculate the magnitude of the electric field in the three regions: inside the smaller cylinder, between the cylinders and outside the larger cylinder.
Where does the field on ́ectrico point to for this system?

(no matter what material these cylinders are made of)

Two 10-cm-diameter electrodes 0.52 cm apart form a parallel-plate capacitor. The electrodes are attached by metal wires to the terminals of a 20 Vbattery.

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What are a) the charge on each electrode, b) the electric field strength inside the capacitor, and c) the potential difference between the electrodes while the capacitor is attached to the battery?

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What are a) the charge on each electrode, b) the electric field strength inside the capacitor, and c) the potential difference between the electrodes after insulating handles are used to pull the electrodes away from each other until they are 1.0 cm apart? The electrodes remain connected to the battery during this process.

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What are a) the charge on each electrode, b) the electric field strength inside the capacitor, and c) the potential difference between the electrodes after the original electrodes (not the modified electrodes of parts D-F) are expanded until they are 20 cm in diameter while remaining connected to the battery?