Physics - April 2007

to estimate the height of a building, a stone is dropped from the top of the building into a pool of water at ground level. how high is the building if the splash is seen 6.8 seconds after the stone is dropped?

2007-04-04 16:49:51 · 2 answers · asked by fantasinhielo 1

2007-04-04 16:19:14 · 7 answers · asked by marathibana b 1

2007-04-04 15:19:36 · 8 answers · asked by tim 3

"The EMF of a charged Van de Graaff generator, or any source of high voltage, can be estimated from the length of the
spark it will produce. Between smooth spheres, in dry air, a spark will jump about 1 cm for every 25 000 V. Between
pointed conductors it will jump 1 cm for every 10 000 V. Under good conditions a Van de Graaff generator might produce a
spark of up to about 15 cm, that corresponds to nearly 400 000 V."

If you've read the above quote you can understand that huge voltages are associated with a Van de Graaff generator. Then why is it that the effect of one of these contraptions on the human body is 0, while the effect of putting your hand in a toaster (ie. 240 V) is potentially lethal?

2007-04-04 15:12:47 · 7 answers · asked by iamdaroot 2

2007-04-04 15:11:42 · 5 answers · asked by toshida t 2

speed of sound in air is 340m/s

2007-04-04 15:10:49 · 3 answers · asked by Anonymous

where would it weight the least? surface of the sun
surface of the earth
surface of the moon
surface of Jupiter

2007-04-04 15:00:40 · 6 answers · asked by stayin alive 2

any ideas?

2007-04-04 14:55:11 · 3 answers · asked by ::h:o:l:l:i:s:t:e:r:: 2

a. 0.00000000000012 C
b. 0.0000022 C
c. 0.0000025 C
d. 0.028 C

2007-04-04 14:54:09 · 3 answers · asked by abcdefghhgfedcba 2

2007-04-04 14:42:17 · 8 answers · asked by Anonymous

Say a hydrogen bomb detonated less that a 1/4 a mile away from you...would you die intantly when the heat hit you or would you feel some pain first..i am just wondering because i one movie i was watching this one gut just completely evaporated....is that true?

2007-04-04 14:11:00 · 5 answers · asked by M R 1

If the big bang took place at an exact time and an exact place and ever since the universe has been expanding at a finite rate; does this give creedance to the idea that there is a finite amount of matter which occupies a finite amount of space? I realize that there are practical difficulties with providing an actual value, I am interested if the concept is theoretically valid. Or in other words my question is: "At a given moment in time can the total amount of matter in existance be quantified?" Thanks.

2007-04-04 14:06:08 · 1 answers · asked by Anonymous

Copper and Aluminum are being considered for the cables in a high-voltage transmission line where each must carry a current of 50A. The resistance of each cable is to be .15ohms per kilometer.
A. If the line carries power from Niagra Falls to New York (500Km), mow much power is lost along the way in the cable? Compute for each choice of cable material

B. the necessary cable diameter

C. mass per meter of cable

2007-04-04 13:56:03 · 1 answers · asked by Shane W 1

2007-04-04 13:21:04 · 6 answers · asked by Anonymous

1. From It's definition, the unit of electric field E is the N/C. An equivalent of E is v/m... why?

2. Why do ten million electrons placed on a solid copper sphere become uniformly distributed on the sphere's surface?

3. The force on an electron in an electric field of 200 v/m is 3.2x10 -17(
4. An electric field of magnitude 200 v/m can be produced by applying a potential difference of 10v to a pair of parallel metal plates by... (the answer is 5cm, but i dont know why..)

5. The resistance of a conductor does not depend on its mass, why?

6. A certain wire has resistance R. The resistance of another wire, identical with the first except for having twice its diameter is..

7. A certain peice of copper is to be shaped into a conductor of minimum resistance. Its length and cross section area should be: (answer is 1/2 L ans 2A) but why?

2007-04-04 13:18:40 · 2 answers · asked by Anonymous

In collision; why is momentum conserved while energy is lost? yet we use the same values for mass and velocity

2007-04-04 12:50:44 · 2 answers · asked by ashenafis 1

A heating coil has a resistance of 4.30 ohms and operates on 120 V. The current in the coil while it is operating is 27.91 amps.

What energy is supplied to the coil in 13 min?

If the coil is immersed in an insulated container holding 27.0 kg of water, what will be the increase in the temperature of the water? Assume that 100% of the heat is absorbed by the water. The specific heat of water is 4180 J/(kg*C°).

At $0.09 per kWh, how much does it cost to operate the heating coil 20 min per day for 30 days (in dollars)?

Can anyone help me as to how to solve this problem??

2007-04-04 12:45:50 · 3 answers · asked by Anonymous

weightless?

2007-04-04 12:30:35 · 6 answers · asked by brandontremain 3

2007-04-04 12:29:10 · 3 answers · asked by Hunny 1

2007-04-04 12:20:27 · 1 answers · asked by LocoFF 1

Cause the vibrations of the individual atoms would be slower *to the outside* and also seem less prone to react - break bend etc. cause the force would be acting on the skin for a fraction of the time (relitively) it would if the ship were standing still.

2007-04-04 12:08:43 · 1 answers · asked by ? 2

Object of the experiment: resonating a tetrahedral electromgnetic array in in 6 polar dimentions. Need to build at least 3 oscillators. Sine wave preferred.

2007-04-04 11:48:29 · 1 answers · asked by Anonymous

2007-04-04 11:30:13 · 6 answers · asked by Crystal Smith 2

Two long parallel wires 6.00 cm apart carry 15.5 A currents in the same direction. Determine the magnetic field strength at a point 12.0 cm from one wire and 13.4 cm from the other.

I don't understand what to do. I saw another one like this question but I'm still confused.. please help ^_^

2007-04-04 11:28:16 · 2 answers · asked by Anonymous

A single sheet of 8.5 X 11 piece of paper dropped from ten feet high at the same time as a five pound rock; How can you get the paper to the ground at the same time as the rock?

2007-04-04 11:21:33 · 11 answers · asked by twiztid_ditzwit 2

2007-04-04 11:07:31 · 2 answers · asked by Brandi williamson 1

An airplane flies on a level path. There is a pressure difference of 510 Pa between the lower and upper surfaces of the wings. The area of each wing surface is about 100 m2. The air moves below the wings at a speed of 80.3 m/s. Estimate (a) the weight of the plane and (b) the air speed above the wings.

2007-04-04 10:52:52 · 4 answers · asked by Colin v 1

is is a nanosecond the smallest time unit?

2007-04-04 10:36:51 · 12 answers · asked by ernestolv 1

If I was to explain the physics of a cell phone for a summative project, what should I talk about? The presentation is 3 minutes maximum, and I have to write a scientific report.

2007-04-04 10:26:49 · 3 answers · asked by Anonymous

2007-04-04 10:19:58 · 4 answers · asked by Terry D 1