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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

Electric Current - Internal Resistance of the Battery

1. A battery with 12-V emf has a terminal voltage of 11.4 V. When it delivers a delivers a current of 20 A to the starter of a car. What is the internal resistance r of the battery? A) how much emf is delivered but the battery above when it delivers a current of 20 A? (b) how much of this power is delivered to the starter?

Volume and Density of a Cylinder

1. A solid uranium cylinder weighs 91.53 N in air and 86.63 N when submerged in water. a. The volume of the cylinder is ----------mt^3 b. The density of uranium is---------kg/mt^3 2. On each heartbeat,about 70 cm^3 of blood is forced from a human heart at an average pressure of approx 105 mm Hg. a. If the heart beats 7

Determining the Voltage of an Unknown Battery in an Old Truck

Please help with the following problem. There is an old truck that has a 6 or 12-volt battery in it which has very little charge left in it. The hood cannot be opened, so to charge the battery, someone uses 3 car batteries (12 volts each) which are placed in series. The reasoning is that if it is either a 6 volt or 12-volt b

Power and Radius Calculations

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.

Sound Intensity and Power

At a distance of 3.8 m from a siren, the sound intensity is 3.6 x 10^-2 W/m^2. Assuming that the siren radiates sound uniformly in all directions, how do you find the total power radiated?

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

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).

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

Impulse and Power

The engine of a model rocket is rated with a total impulse of 5.00 N seconds and a thrust duration of 1.20 seconds. What is the average force exerted by the engine? I believe the answer is 4.17 N. I need to see each step and formula to solve this question.

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

Power delivered to a resistor

Four resistors are connected to a battery with a terminal voltage of 15 V, as shown in attached figure. Determine the power delivered to R2. (R1 = 20 ohm;, R2 = 45 ohm)

Electrical energy and potential energy

A portable CD player uses a current of 7.2 mA at a potential difference of 3.5 V. Suppose the player has a mass of 0.47 kg. How long could the player operate (in minutes) on the energy required to lift it through a height of 1 m?

Specific absorption rate (SAR) of radio frequency power

Derive an equation for the relationship between electric field in a homogeneous volume of tissue and specific absorption rate (SAR) of radiofrequency power. Assuming a conductivity of the tissue of 1S/m, what electric field corresponds to an SAR of 1W/kg?

Modern Physics with de-Broglie and Electron Microscope

1. Wavelength of particles a. Consider a dust particle of diameter d =1 micron, mass m= 10^-15 kg, and speed v = 1 mm/s. Calculate the de Broglie wavelength of the particle and compare with the particle's size. b. Now consider a thermal neutron, i.e, a neutron (m=1.67 x 10^-27 kg) with a speed corresponding to the average the

Problem on Motion along Straight Line

A helicopter carrying Dr. Evil takes off with a constant upward acceleration of 5.0 m/s^2 . Secret agent Austin Powers jumps on just as the helicopter lifts off the ground. After the two men struggle for 10.0 s, Powers shuts off the engine and steps out of the helicopter. Assume that the helicopter is in free fall after its engi

Velocity and Acceleration Positivity

I need help with the following two problems in the attachment. How do I tell if velocity and acceleration are positive, negative or zero? Please see the attached file. 1) The next figure above shows the velocity vectors corresponding to the upward motion of the power ball. Indicate whether its velocity and acceleration, respe

Dimensional Analysis, Vectors, etc.

Please see instructions on attachment. Please solve each and give a complete detailed step by step solution to solving each problem no matter how easy. I am trying to learn and not an expert. Give answer and way to solve. Adult student trying to make my way through all this and need your help! 1) A flat circular plate o