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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

### 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

### 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

### 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

### Maximum power from geothermal energy

See attached file.

### 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.

### 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.

### Electrical Power

The instantaneous current and voltage in an electrical circuit are given by: i = Icos(50pi*t) v = Vcos(50*pit + pi/6) Determine an expression for the instantaneous power in the circuit p = iv, "AS THE SUM OF 2 COSINES" If I is 0.003 Amps and V is 5 volts, calculate the maximum value of p, giving the answer in watts corre

1. The 50-lb load is hoisted by the pulley system and motor M. If the crate starts from rest and by constant acceleration attains a speed of 15 ft/s after rising 6 ft, determine the power that must be applied to the motor at this instant. The motor has an efficiency ε = 0.76. Neglect the mass of the pulleys and cable. 2. Ro

### Observable in Heisenberg Picture

Consider the observable q_u = u_1q_1+u_2q_2+u_3q_3 , where the q_i are the Pauli matrices and where u = (u_1,u_2,u_3) in R^3 and the Hamiltonian is H = q3. Compute the observable (q_u)_H (t) derived from q_u in the Heisenberg picture.

### Power Cycle for a Piston-Cylinder Device

A power cycle for a piston-cylinder device is described by the following four processes: 1→2 Isothermal compression from T1 = 300K, P1 = 100 kPa to P2 = 600 kPa. 2→3 Constant pressure heat addition until the temperature is T3 = 800K. 3→4 Isentropic expansion until the volume at state 4 equals the volume at state 1. 4

### Engines and refrigerators

I have done an example to calculate the actual max efficiency of a power plant given the temperatures of both the hot and cold reservoirs. My book, however, tells me nothing about how to calculate any of the following questions. A power plant produces 1 GW of electricity, at an efficiency of 40%. (a) At what rate does th

### Putting Prefixes in Order

Put these prefixes in order of increasing size. Put 1 for the smallest, 2 for the next largest, etc. 1. tera- 2. centi- 3. nano- 4. giga- 5. milli- 6. mega- 7. micro- 8. kilo-

### Poynting vector from the antenna of a cell phone

An old analog hand-held cellular telephone operates in the 860 to 900 MHz band and has a power output of 0.600 W from an antenna 10.0 cm long. a. Find the average magnitude of the Poynting vector 4.00 cm from the antenna, at the location of a typical person's head. Assume that the antenna emits energy with cylindrical wave

### Problems on deflation of electron in a Thomson's e/m apparatus, diffraction grating, radiation and Compton effect.

(See attached file for full problem description with diagrams) --- 1. An electron entering Thomson's e/m apparatus (Figure 3.2 and 3.3) has an initial velocity (in horizontal direction only) of 0.7 107 m/s. Lying around the lab is a permanent horseshoe magnet of strength 1.3 10-2 T, which you would like to use. Figu

### The amount of radiant power produced by the sun

The amount of radiant power produced by the sun is approximately 3.9 x 10^26 watts. Assume the sun is a perfect blackbody sphere with a radius of 6.96 x 10^8 meters, find its surface temperature (in Kelvins).

### Four questions involving motion under gravity, conservation of energy, force, work and energy

1. An object of mass 0.23 kg is initially at the origin and is acted on by the sole force F=(0.50 N)i. After a certain amount of time, the object is at a position r=(0.80 m)i. What is the changed in the object's kinetic energy? 2. 74 gram ball is tossed straight up in the air, rises to a maximum point, then falls back until

### Problem Set in Classical Physics

When a mass of 25.0 grams is suspended from a certain spring and lowered slowly until the spring stops stretching, the spring stretches 2.00 cm. What is the spring constant of the spring? a. 1.25 N/m b. 0.800 N/m c. 7.85 N/m d. 12.3 N/m A mass of 40.0 grams is attached to a vertical spring with a spring constant k = 2

### Hermitian Conjugate of (d/dx)x^2(d^2/dx^2) + (1+3i)xd/dx

Note that all the derivatives in the problem are partials with respect to x, and the i is an imaginary number Find the Hermitian Conjugate (operator O-dagger) of the operator O (operator) = (d/dx)*(x^2)*(d^2/dx^2) + (1 + 3i)*x*d/dx