Explore BrainMass


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?

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.

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


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

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:

Power Consumption of a Refrigerator

The Electric Meter in a House indicates that the refrigerator consumes 70.0 kWh in a week. a. What is the power consumption of the refrigerator? b. Assuming it is connected to a potential difference of 120V, how much current does the refrigerator draw?


Sam, whose mass is 75 kg, takes off across level snow on his jet-powered skis. The skis have a thrust of 200 N and a coefficient of kinetic friction on snow of 0.1. Unfortunately, the skis run out of fuel after only 10 s. What is Sam's top speed? (in meters/second)How far has Sam traveled when he finally coasts to a stop? (in me

Various Physics Problems

Hi, I am having trouble doing these problems listed below. Please show me how to solve these problems for future reference. Thank you very much. 1. You are told that the volume of a sphere is given by V = pie d/4, where V is the volume and d is the diameter of the sphere. Is this equation dimensionally correct? (Use SI unit

Resistors - Finding the Current

Hi. Can someone please help me with the following problem? I'll try to draw the circuit (with battery and 4 resistors), but I don't know if all the spacing will come out right. The "///" are resistors. Basically, it's a circuit with a 15-V battery and 4 resistors. First you hit R1, which = 11 ohms. Then there are two paths

RL Circuit: Calculating Power

Question: An ac generator with a frequency of 1.00 kHz and an rms voltage of 24 V is connected in series with a 2000 ohm resistor and a 0.365 H inductor. (a) What is the power factor for this circuit? (b) What is the average power consumed by this circuit?"

Average Power fun

Scott, riding for the Mercury team, won the 2002 Mt. Rushmore Hill Climb bicycle race with a winning time of 1 hour 50 minutes 20 seconds. The race is 28 miles in length with a total altitude gain of 7000ft. Scott weighs in at 130 lbs and his hill climbing bike weighs 17 lbs. The total weight of his water bottles, shoes, clot

Calculating resultant force and change in potential energy

The speed of a 4.0kg object is given by (2t) m/s, where t is in seconds. At what rate is the resultant force on this object doing work at t = 1 second? Answers: a) 48 W b) 40 W c) 56 W d) 16 W A 10kg object is initially at the top of a rise, at point A. It then moves down to point B. Choose point B to be your zero leve

Current & Resistance

1. An ant is 3 cm from a magniflying lens with a focal length of 5 cm. The image of the bug is A. real, upright, enlarged, other side of lens B. virtual, upright, enlarged, same side of lens C. virtual, smaller, inverted, same side of lens D. real, upright smaller, other side of lens A 5kW h

Wave properties of particles

The resolving power of a microscope is proportional to the wavelength used. A resolution of approximately 1.0 x 10-11 m (0.01 nm) would be required in order to "see" an atom. (a) If electrons were used (electron microscope), what minimum kinetic energy would be required for the electrons? (b) If phtons were used, what minimum p

Conducting Rod

A conducting rod of length l moves on two horizontal, frictionless rails, as shown in the attached file 'Figure P31.20'. If a constant force of 1.00 N moves the bar at 2.00 m/s through a magnetic field B that is directed into the page, (a) What is the current through the resistor R? (b) What is the rate at which energy is d

Finding work using time dependent Force function.

I only need the last five parts explained to me. See attached PDF file for the question ! Homework 5-1 Due date: Mon 22 Mar 2004 09:00:00 AM MST 18 point(s) Pulling Out Tree Stump You are in a truck trying to pull out a tree stump. The mass of the tree stump m is 170.0 kg. You have attached the winch at the f

Momentum, Velocity and Power

1. A 1500kg automobile starts from rest on a horizontal road and gains speed of 72km/h in 30 s. a) What is the average power required of the car at the end of the 30 s? b) What is the average power required of the car during the 30 s interval? c) What is the instantaneous power at the end of the 30 s interval, assuming t

Current and Power in a Resistor

A 60.0 ohm resistor is connected in parallel with a 115.0 ohm resistor. This parallel group is connected in series with a 15.0hm resistor. The total combination is connected across a 15.0-V battery. Find the current and power in the 115 ohm resistor.