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# Power

### Work, Energy & Power Problems of Objects

1) an object initially at rest reaches a velocity of 30m/s in 6 seconds, how much work is done during this time interval? 2) a roller coaster car with a mass of 1000kg starts at ground level and reaches a maximum height of 128m. what is the change in potential energy for the car? I f all the potential energy is turned into ki

### Calculating maximum total power needed: Ski hill example

Squaw Valley ski area in California claims that its lifts can move 47900 people per hour. If the average lift carries people about 200 m (vertically) higher, estimate the maximum total power needed. (Assume an average mass per person of 70 kg).

### Current Through Series of Resistors

Three resistors having resistances of 1.20ohms , 2.60ohms , and 5.00 ohms are connected in series to a 26.0 V battery that has negligible internal resistance. 1) Find the equivalent resistance of the combination 2) Find the current in through 1.60, 2.50, and 5.00ohms resistors. 3) Find the total current through the ba

### Electric Circuit and Extreme Inelastic Collision

1. An electric d.c. circuit is attached to a 12 volt battery and has a 3-ohm resistor in it. Find the current flowing through the circuit. What is the current in an ac circuit wit 120 volts and a 60 watt light bulb? 2. A 500 kg truck moving at 30 m/s strikes a parked 300kg car. They connect together and move forward. What ki

### Parallel and Series Circuits

1. Why are batteries sometimes installed as parallel circuits and other times installed as series circuits? 2. What affects the way batteries are positioned? What are the benefits for the different positions? 3.How does electricity work together with magnetism? How are the two connected? 4. What are some examples of pr

### Van der Waals equation of state as virial expansion

Express the van der Waals equation of state as a virial expansion in powers of 1/(V_m), and obtain expressions for B and C in terms of the parameters a and b. The expansion you will need is (1 - x)^(-1) = 1 + x + (x^2) + ... Measurements on argon gave B = -21.7 (cm^3)/mol and C = 1200 (cm^6)/(mol^2) for the virial coeffici

### Generating function for the Hermite polynomials

Expand the generating function for the Hermite polynomials. Please see the attachment. Please show each step in the solution.

### Set of problems on mechanics

Chapter 7: 11. Engine 1 does twice the work of engine 2. Is it correct to conclude that engine 1 produces twice as much power as engine 2 explain? 12. Engine 1 produces twice the power of engine 2. Is it correct to conclude that engine 1 does twice as much work as engine 2? Explain. 38. You raise a bucket of wat

### Power of a Propeller Turbine

Estimate the power available in a tidal stream flowing at 3m/s using a 5m diameter propeller turbine.

### Anti-reflection coating

A linearly polarized plane wave of wavelength lembda, is travelling in air and ia incident normally on a plane sheet of glass. Show that the ratio of the reflected to the incident electric field amplitude is (n(glass)-n(air))/(n(glass)+n(air)) where n(air) and n(glass) are the refractive indices of ai

### resolving power of Fabry-Perot etalon plates

Could you please do the problem attached? Thank you. A Fabry-Perot etalon is used to resolve two spectral lines of equal intensity, and wavelengths of 670.776 nm and 670.791nm. The etalon plates have a reflectivity R = 0.85. Determine the minimum separation of the plates, d, for which the two lines are just resolved.

### Complex Refractive Index and Power Reflection Coefficient

Show that the complex refractive index of a conducting medium can be expressed as n = λ0(1+i)/2 πδ and n = λ0(1-i)/2πδ where δ is the skin depth. Hence find the power reflection coefficient for an EM wave incident from free space on a good non-magnetic conductor at normal incidence. Show that the energy lost per unit area

### Sound Intensity and Decibels

When four quadruplets cry simultaneously, how many decibels greater is the sound intensity level than when a single one cries?

### Average Power and Mechanical Advantage of Pulleys

1. Calculate the average power in kilowatts required to pull a car up a ramp if the amount of work is 250 kj over a period of 45 seconds. 2. Calculate the mechanical advantage of a group of pulleys used to raise an engine from a car. The engine is raised 1.2 m with the pulleys when 4.8 m of rope is pulled through the pulleys.

### Maximum power from geothermal energy

See attached file.

### Reflection at the boundary between two non-magnetic media

A plane electromagnetic wave is incident at angle theta to the normal on the boundary plane separating two non-magnetic media with relative permitivities e1 and e2. For the case in which the electric vector is in the plane of incidence, show that any wave reflected from the boundary has the same frequency as the incident wave. S

### The Poynting Vector and Power Dissipation

Consider the integral of the inwardly directed normal component of the Poynting vector over a surface S bounding a volume V of a linear, isotropic, homogeneous, conducting medium. Show that this quantity can be identified with the sum of the rate of change of the electromagnetic energy and the power dissipated when there is a fr

### Voltages and power

In Europe the standard voltage in homes is 220V instead of the 120V used in the United States. Therefore a 100W European bulb would be intended for use with a 220V potential difference. 1) If you bring a 100W European bulb home to the United States, what should be its U.S. W power rating? 2) How much current in A will the 10

### Transformers in a generating station

A generating station is producing 1.1 x 10^6 W of power that is to be sent to a small town located 8.0 km away. Each of the two wires that comprise the transmission line has a resistance per kilometer of length of 5.0 x 10^-2 ohms/km. (a) Find the power lost in heating the wires if the power is transmitted at 1100 V.

### Simple Harmonic Motion of a Bungee Jumper

Any help with this problem would be great! A bungee jumper, whose mass is 82 kg, jumps from a tall platform. After reaching his lowest point, he continues to oscillate up and down, reaching the low point two more times in 9.6s. Ignoring air resistance and assuming that the bungee cord is an ideal spring, determine its spr

### Probabilty of an electron inside the hydrogen nucleus.

See attached file.

### resolving power of grating light diffraction

A source emits 531.62 nm and 532.82 nm light. 1.) What minimum number of lines is required for a grating that resolves the two wavelengths in the first-order spectrum? 2.) Determine the slit spacing for a grating 2.08 cm wide that has the required minimum number of lines. Answer in units of um. Please show all wor

### Sketch a circuit and phasor diagram; magnitude of voltage

See attached file for full problem description. Only need questions 4, 5, and 6.

### Power Generation: Efficiency and the output.

Question 1 [2] In a coal fired power plant the output from the steam turbine is 500 MW in the form of shaft power. This is connected to an electric turbine with an efficiency of 96 %. The output voltage from the electric generator is 2000 V. What is the power output from the electric generator? What is the electric current

### RMS and Power Factors

See attached file for full problem description. 5. A 120-V rms voltage at 60.0 Hz is applied across an inductor, capacitor, and a 100-ohm resistor in series. If the maximum value of the current in this circuit is 1.60 A, what is the rms value of the current in this circuit? 6. What is the power factor of and RLC series cir

### Sound intensity

A typical adult ear has a surface area of about 1.9 10-3 m2. The sound intensity during a normal conversation is about 3.6 10-6 W/m2 at the listener's ear. Assume the sound strikes the surface of the ear perpendicularly. How much power is intercepted by the ear?

### Alternating Current Circuits

See attached file for full problem description. 18. A 120-V rms voltage at 1000 Hz is applied to a resistor and an inductor in series. If the impedance of this circuit is 110 ohms, what is the maximum value of the current? 19. A 200-ohm resistor, a 40.0-mH inductor and a 2.00-uF capacitor are connected in series with a 120

### Power - How much time does it take to lift the piano?

A 2.40 * 10^2 kg piano is being lifted at a steady speed from ground level straight up to an apartment 10.0 m above the ground. The crane that is doing the lifting produces a steady power of 4.00 *10^2 W. How much time does it take to lift the piano?

### Conversion of units of power.

One kilowatt-hour (kWh) is the amount of work or energy generated when one kilowatt of power is supplied for a time of one hour. A kilowatt-hour is the unit of energy used by power companies when figuring out your electric bill. Determine the number of joules of energy in one kilowatt-hour.

### Decibels and Sound

Question: You are at a party with your four closest friends, Alice, Bob, Charlie, and Eve. Music is playing in the background very softly you hear it at a level of 35 dB. All of your friends are talking at once and given their volume and your proximity to them you hear Alice at 45 dB, Bob at 42 dB, Eve at 48 dB and Charlie talki