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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

Wavelength of wave

The vertical displacement of a string is given by y(x,t) = (6.00mm) cos[(3.25m to the power of (-1)) x - (7.22 s to the power of (-1))t]. What is the wavelength of the wave?

Frequency of Motion

The position of a mass that is oscillating on a spring is given by x=(18.3 cm) cos[(2.35s to the power of -1)t]. What is the freqency of this motion?

Immersion heater

A small immersion heater is rated at 380 W. Estimate how long it will take to heat a cup of soup (assume this is 295 mL of water) from 18.2oC to 48.4oC.

Harmonic Motion and Spring Constant

A spring with a spring constant of 1.8 x 10 to the 2nd power N/m is attached to a 1.6 kg mass and then set in motion. What is the period of the mass-spring system in units of s and the frequency of the vibration in units of Hz?

Power/Current Required

An X-ray machine operates from a 220V supply. The machine power is 800W and the supply must also supply six 24W, 220V indicator lights. Please answer all questions with full explanations thankyou 1) What is the total power required? 2) What is the current drawn from the 220V supply? 3) A transformer with 250 turns in

Properties of laser beam

What properties of a laser beam are used in: (a)holography- (b)punching holes in baby bottle (c)monitoring location of the crater of a dormant volcano by interferometry- (d)laying straight railroad tracks-

The Intensity of an Earthquake Wave

The intensity of a particular earthquake wave is measured to be 2.09à?106 W/m2 at a distance of 123 km from the source. What was the intensity when is passed a point only 4.39 km from the source? Give answer in W/m2.

Find the power dissipated by the resistor identified with a star.

Refer to attached picture file. Each resistor in the following circuit is 6.00 ohms. What is the equivalent resistance between points a and b? Find the equivalent resistance of the resistors between points a and b. Find the power dissipated by the resistor identified with a star.

Find noise from a helicopter rotor

The noise from a helicopter rotor is distributed equally in all directions. If the rotor generates 70 watts of sound power, find the intensity level of the sound in dB on the ground directly beneath the helicopter when its altitude is 120 m. Also find the altitude in meters for the sound to be reduced to 60 dB at the same locati

Power from Radium

It was stated that around the turn of the 20th century some researchers discovered that radium generated heat. Assuming that you have a pure 1 Ci sample of Ra-226, what is the maximum potential power (in Watts) that you could recover (at 100% efficiency) from this sample.

Power of a sound wave: Definition of Intensity level Beta

What is the power of a sound wave (B = 32 dB) passing through an area of 12.5 cm^2? Suppose the same sound wave passes through an area of 25 cm^2. What is it's intensity level? Please explain to me how to use the Definition of Intensity level Beta B= 10 log (I/Io) in this problem.

Telescope/resolution

The Hubble Space Telescope (HST) orbits Earth at an altitude of 613 km. It has an objective mirror that is 2.4 m in diameter. If the HST were to look down on Earth's surface (rather than up at the stars), what is the minimum separation of two objects that could be resolved using 550 nm light? [Note: The HST is used only for astr

Lenses/compound microscope

Hi. Can someone please show me how to do the following problem? "The medium-powered objective lens in a laboratory microscope has a focal length f-objective = 4.00 mm. (a) If this lens produces a lateral magnification of -40.0, whiat is the distance from the object to the objective lens? (b) What is the focal length of an ey

Power and Resistance

A wire 1.2 m long and 0.4 mm diameter has a resistance of 4.9. Calculate the resistance of another wire of the same material whose length is 0.8 m and diameter is 0.24 mm.

What is the power dissipated in each of the resistors

Please see attached for diagram. If points A and B in the figure below are connected to a 10 V battery, what is the power dissipated in each of the resistors assuming that R = 65 ohms. 12 ohms resistor : 55 ohms resistor : 65 ohms resistor :

Determine the Thermal Efficiency

A turboprop producing 1000 kW drives a propeller operating at 85% propulsive efficiency. If the fuel flow to the engine is 0.07 kg/s, determine the overall thermal efficiency of the engine.

Determine Fuel Flow Engines

A turboprop engine produces a "Brake Specific Fuel Consumption" of 0.5 lb/bhp/hr. Determine the fuel flow (in kg/s) required at this bsfc to produce 800 bhp of power.

Thermodynamics - Carnot cycle problem

An air-conditioning system operating on the reversed Carnot cycle is required to remove heat from the house at a rate of 25 kJ/s to maintain its temperature constant at 20°C. If the temperatures of the outdoors is 35°C, the power required to operate this air-conditioning system is:

Sound Response Details

Hi, I need some assistance with the following physics problems. Please view the attachment to see the full set of questions.

Radioactive Decay as a Power Source

Strontium-90 is to be used in a radioisotopic thermoelectric generator (RTG) for powering a navigation beacon located in the arctic. a) How much of the Sr-90 activity is required to generate 50 W of electric power if the conversion efficiency from heat to electricity is 30%? Tip: You must take into account the fact that Sr-90