Physics - July 2007

A beam of plane-polarized microwaves is incident upon an aerial which is positioned to give maximum response. The aerial is rotated at an angle of 30 degrees to the plane of polarization about the direction of the incident waves.
Calculate the % reduction in the amplitude of the signal now received from the aerial.

2007-07-30 10:45:49 · 1 answers · asked by polol 2

A compass has a magnetized needle inside of it that points to magnetic north. What keeps the needle from being effected by metal around it? Is it the liquid inside?

2007-07-30 10:41:27 · 4 answers · asked by robertlash19 2

Like, Theoretically, if someone started working on a cyborg, on the basic components of a cyborg in their home, and did not live near a university, what could they do to improve and develop it better?
Websites, links on electronic circuitry, robotics history, resources, universities that specialize in this, models and studies done, etc???

2007-07-30 09:57:55 · 2 answers · asked by Anonymous

I have heard on the grapevine that marble always remains cooler than room temperature. Could someone explain if this is just a myth or fact?

2007-07-30 09:54:49 · 8 answers · asked by tad_pole99 1

in what state will you find yourself when you awake?

2007-07-30 09:43:34 · 2 answers · asked by Alexander 6

2007-07-30 09:30:01 · 24 answers · asked by Anonymous

A platform of mass 0.8 kg is supported on four springs (only two springs are shown in the picture, but there are four altogether). A chunk of modeling clay of mass 0.6 kg is held above the table and dropped so that it hits the table with a speed of v = 0.9 m/s.

The clay sticks to the table so that the the table and clay oscillate up and down together. Finally, the table comes to rest 6 cm below its original position.

a) What is the effective spring constant of all four springs taken together?

b) With what amplitude does the platform oscillate immediately after the clay hits the platform?

2007-07-30 09:04:03 · 3 answers · asked by Anonymous

2007-07-30 08:18:28 · 7 answers · asked by Alexander 6

what maximum speed could such spaceship achieve, assuming D+D->He4 reaction and 100% efficient rocket motor?

Note:
usually D+D fusion produces either or He3+n or T+p, but lets not worry about this. Consider that engineers solved all problems and D is on input, and He4 on output.

2007-07-30 08:14:54 · 4 answers · asked by Alexander 6

2007-07-30 07:55:33 · 1 answers · asked by Tim F 1

Can somebody define schrodinger's cat in a simple manner? I looked it up on Wikipedia and I didn't get a word (yeah....not that bright). Thanks!

2007-07-30 07:54:18 · 4 answers · asked by Insert nickname here 2

A small block of mass M is released from rest at the top of the curved frictionless ramp. The block slides down the ramp and is moving with a speed of 3.5v when it collides with a larger block of mass 1.5M at rest at the bottom of the incline. The larger block moves to the right at a speed 2v immediately after the collision. Express the answers in terms of the variables given and fundamental constants.

a) Determine the h of the ramp from which the small block was released.
b) determine the speed of the small block after the collision.
c) The larger block slides a distance D before coming to rest. Determine the value of the coefficient of kinetic friction between the block and the surface.

please show me steps an formulas, i am so confused.

2007-07-30 07:10:15 · 1 answers · asked by Anonymous

A uniform metal rod of mass 100 kg and length L (=2.5 meters) is suspended from the side of a building as shown in the figure. On the far end a mass of 100 kg is hung by a rope, (distance L from the building). The rod is connected to the building on the left end by a pivot, (and a force F is extend on the rod by the pivot). To hold thips up a strong cable is attached a distance L/4 from the pivot (and has a tension T on it).
a)The system is in equilibrium.
Using rotational equilibrium and torque, find the tension in the cable.
b) Using net forces, calculate the force the pivot exerts on the rod.

2007-07-30 06:43:53 · 2 answers · asked by Anonymous

1. If you add a few chunks of ice to a tstyrofoam container with water and do not stir it, then teh temperature of the mixture would be significantly higher than the expected 0 degrees C. Please explain what is happening.

2. Two objects are made from the same material. They have different masses and temperatures. If the two are placed in contact, will they experience the same temperature change.? if not, then which object will experience the greater temperature change?

2007-07-30 06:36:58 · 2 answers · asked by Sandesh R 1

Particle A and Particle B are held together with a compressed spring between them. When they are released, the spring pushes them apart, and they fly off in opposite directions, free of the spring. The mass of A is 2.00 times the mass of B, and the energy stored in the spring was 60 J. Assume that the spring has negligible mass and that its stored energy is transfered to the particles. Once the transfer is complete, what are the kinetic energies of (a) particle A and (b) particle B

2007-07-30 06:32:59 · 3 answers · asked by Allan C 1

if the mass of an object is 80n and the force is 4n what is the acceleration?

2007-07-30 06:25:45 · 4 answers · asked by intelligent girl 2

1. When developing the expression for the angular momentum of a particle, a step occurs where mv × v is set to zero. The reason for this is... v = 0, the cross product of a vector with itself is zero, m = 0?
2. The torque can be expressed as the time rate of change of the.... moment of inertia, linear momentum, angular momentum?
3. In the “Newton’s second law in angular form", τnet is... the torque due to all forces, the torque due to external forces only, the torque due to internal forces only?
4. When the angular momentum changes, the change in the angular momentum vector is.. parallel to the force vector, parallel to the angular momentum vector, parallel to the torque vector?

2007-07-30 05:54:03 · 1 answers · asked by A 2

Gravity is due to the warping of space-time. Unlike the strong, weak and electro magnetic forces (whos nature is unknown), gravity it cause by the shape of space, so why is it still refered to as one of the forces along with the others?

2007-07-30 05:46:51 · 8 answers · asked by wisemancumth 5

2007-07-30 05:22:48 · 4 answers · asked by Anonymous

An 8kg box and a 10kg box that are attached by a rope that passes over a frictionless pulley slide on a frictionless inclines.

a.Find the acceleration of the boxes and the tension in the rope.

Here is a picture of the boxes
http://img521.imageshack.us/my.php?image=ps3dm6.jpg

2007-07-30 05:14:10 · 1 answers · asked by physics maniac 2

Application of Newton's Laws. A 4kg block resting on a 30 degrees incline is attached to a second block of mass m by a cord that passes over a smooth peg. The coefficient of static friction between the block and the incline is 0.4.

A. Find the range of possible valuesa for m for which the system will be in static equilibrium.

B. If m=1kg, the system will be in static equilibrium. What is the frictional force on the 4kg block in this case?

--
here is the link on the picture of the blocks so that you easily understand the problem
(http://img508.imageshack.us/my.php?image=ps1nc2.jpg)

2007-07-30 05:09:49 · 1 answers · asked by physics maniac 2

2007-07-30 04:58:20 · 6 answers · asked by roger m 2

If a true falls in the woods and nobody is there to hear it, did it make a sound.

2007-07-30 04:37:26 · 5 answers · asked by Anonymous

a star has a planet held in orbit by gravitational attraction if the mass of the star were doubled what effect would this have on the gravitational attraction between the star and the planet ? explain your answer

2007-07-30 04:36:18 · 3 answers · asked by Anonymous

I know the whole thing about + and - forces, but I still cannot see the casual link between them. What is it that pulls the two magnets together? Can anybody explain to me why this is?

2007-07-30 04:32:29 · 12 answers · asked by george 3

2007-07-30 04:03:15 · 2 answers · asked by suraksha k 2

2007-07-30 03:07:49 · 13 answers · asked by ramboo 1

Look at the following videos, proving controlled demolition
and an "inside job" false-flag fabricated terror attack on 9/11:

http://www.truth911.net

Watch the 90 minute films:

9/11 Mysteries

Loose Change 2

Terror Storm 2

and look at these ABC News videos & amateur videos

http://www.youtube.com/results?search_query=molten+metal+wtc&search=Search


showing MOLTEN METAL dripping out of the South Tower,
just moments before its complete free-fall collapse right down
to the ground... Steel has a melting point of 1532 Celcius, but
open air fires (due to limited oxygen supply) only burn as hot
as 233 - 250 Celcius... not even hot enough to start softening
steel at 300 Celcius! SO HOW COULD AIR FIRE MELT
STEEL? when you all know that your cooking pots and pans
and BBQ hotplates made of steel do not melt, or glow yellow
or red hot when exposed to air fire? HOW?

Why is it people are too stubborn to accept this physical
evidence that proves an inside job?

2007-07-30 03:01:09 · 5 answers · asked by Anonymous

Explain briefly why it is or is not possible in each case

2007-07-30 02:50:05 · 5 answers · asked by polol 2

2007-07-29 23:21:16 · 7 answers · asked by Anonymous