Explore BrainMass


X-ray production

X-ray production: dependence of wavelength and intensity on various parameters. Tips to remember.


A positive charge of 2X10-12 Coulombs placed 10cm from another charge experiences a repulsive force of 9X10-9 Newtons. What is the sign and magnitude of the other charge?

Thermal conductivity comparison

Which of the following cylindrical rods of the same material with its ends at the same steady difference of temperature will conduct maximum heat ? 1. Lenght 100 cm & radius 1 cm 2. length 200 cm & radius 1 cm 3. length 400 cm & radius 2 cm 4. length 100 cm & radius 2 cm

Lorry descending a hill: Force applied by the brakes

A lorry travelling on the level road at 40 km/h can be stopped by its brakes in a distance 16 m. Find the speed from which it can be brought to rest in the same distance when descending a hill whose angle of slope is Sin^-1 [1/15]

Sound waves: temperature dependence

(1) How will the pitch of an organ pipe be affected by change of temperature and humidity ? (2)Why do the sound waves travel through longer distances during night than during day ? (3)When a hot body cools a cool one, are their temperature changes equal in magnitude ?

Calculating the specific temperature that balls will sink in benzene.

Benzene has a density of 0.90gm/cm^3 at 0 deg C and a coefficient of cubical expansion of 0.0012 per deg Celsius. Wooden balls (of density 0.88g/cm^3) therefore float in it at 0 deg Celsius. If the wood has a mean coefficient of linear expansion of 4 x 10^-5 per deg Celsius, calculate at what temperature the balls will just sink

Springs: Different force constants.

Springs A and B are identical except that A is stiffer than B, that is the force constant Ka is greater than the force constant Kb. On which spring is more work expended if, (a) They are stretched by the same amount? (b) They are stretched by the same force?

Archimedes Principle: An object, part aluminum, part wood, floats in water.

See attached file. Two blocks are cemented together top to bottom and the whole object is placed in water. Known values are the density of the wood Dw= .650 kg/m^3, of aluminum Da = 2700 kg/m^3, and of water Dliq= 1000 kg/m^3. See attachment #1 for diagram, (not to scale). PART a. If the object barely floats, with the top

Boiler saftey valves

NOTE: MOVED FROM MECHANICAL ENGINEERING TO PHYSICS BECAUSE MECHANICAL OTAs UNABLE TO ADDRESS IN TIME. An HRT boiler burning gas with 5.9MJ calorific value and 34m^2 of heating surface not exceeding 1200 kpa,needs safety valves.Find the code requirement for a)safety valve capacity b)max diameter of surface for connection c)ma

Working with elastic potential energy and a bowstring.

An archer pulls the bowstring back for a distance of 0.470 m before releasing the arrow. The bow and string act like a spring whose spring constant is 425 N/m. (a) What is the elastic potential energy of the drawn bow? (b) The arrow has a mass of 0.0300 kg. How fast is it traveling when it leaves the bow?

Moment of Inertia of a thin uniform rod by integration

A thin, uniform rod has length L and mass M. a. Find by integration its moment of inertia about an axis perpendicular to the rod at one end. b. Find by integration its moment of inertia about an axis perpencicular to the rod at its center of mass.

Projectile problemA marble fired from a roof at a known angle.

A marble is fired at angle +30° from a roof top x,y origin 50 m above ground with velocity such that it falls into a bowl on the ground at (218, -50). a. Find the original speed Vo. b. Find the total time of flight of the marble. See diagram attachment for picture showing known data.

Working with spring oscillations and friction.

A block attached to a spring is acted on by a spring with spring constant k and a weak frictional force of constant magnitude f. The block is pulled a distance Xo from the equilibrium and released. It oscillates many times and eventually comes to rest. a) Show that the decrease of amplitude is the same for each cycle of osci

Electricity Problem

A +30e-6 charge is placed 32 cm form an idnetical +30e-6 charge. How much work would be required to move a +50e-6 test charge from a point midway between them to a point closer to either of the charges?

Problem relating to centroid

The asking problem: For the semiannular area, determine the ratio of r1 to r2 for which the centroid of the area is located at x=-1/2*r2 and y=0. Note: This problem is a 2D problem and not a 3D. It was taken from the «Distributed forces: Centroids and Centers of Gravity» section of my static course. The files is in word97

Sound waves

A very large pipe is set up in a science museum. It is open at both ends, and it is large enough to walk inside it. A large loud speaker is set up at one end of the pipe. A student walks along the pipe and makes the following observations. While walking through the entire length of the pipe the student encountered 3 soft zones

Determining the elongation in a spring when the mass is immersed in water.

A copper piece of mass 10g is suspended by a vertical spring. The spring elongates 1cm over its natural length to keep the piece in equilibrium. A beaker containing water is now placed below the piece so as to immerse it completely in water. Find the elongation of the string. Density of copper is 9000 kg/m^3 g = 10 m/s^2

Working with tension in a pendulum.

A simple pendulum having a bob of mass m undergoes small oscillations. If theta is the small angle that makes with the vertical at the extreme positions, find the tension in the string as a function of the angle made by the string with the vertical. When is the tension maximum and when it is a minimum?

Electomagnetic Induction

1. Imagine a superconductor in its normal state in the shape of a ring immersed in a magnetic field parallel to the central axis (that is, perpendicular to the plane of the ring.) Suppose the ring is cooled and becomes superconducting. (a) Describe what happens to the field (b) If the ring is pulled parpendicularly out of the

Motion with Constant Acceleration Two space crafts approaching on parallel paths

Spacecraft A and spacecraft B are traveling on paths parallel to an x axis. Initially, at t=0, A is located at XoA= -30 m, moving at VoA=+25 m/sec, and having constant acceleration aA = -4.5 meters per second squared. Also at t=0, spacecraft B is located at XoB= +60 m, moving with initial velocity VoB= -9.5 m/sec and accelerati

Sound Waves are explored.

1. Imagine two symmetrical pulses that are identical in every way, except tht one is inverted. These pulses are moving toward each other on a rope in opposite directions. What happens to the energy of the rope at the instant of complete cancellation? 2. In the real world, a pulse sent down a very long, taut rope diminishes in