Physics (Science & Mathematics) - March 2007

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What is the ratio of the volume of the bubble as it reaches the surface (Vs) to its volume at the bottom (Vb)?

A diver named Jacques observes a bubble of air rising from the bottom of a lake (where the absolute pressure is 3.50 atm) to the surface (where the pressure is 1.00 atm). The temperature at the bottom is 4.0 degrees celcius, and the temperature at the surface is 23.0 degrees celcius .

2007-03-26 01:54:21 · 2 answers · asked by RhondaJo 2

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attenuation coefficient?

a mixture of water that has 12 keV phtons.
Weight fractions of Hydrogen and Oxygen are 2/18 are 16/18 respectively.

thus the net aborption coefficient is
U = (0.045 * 2/18) + (0.283 *16/18)

I dont understand where 0.045 and 0.283 come from? Help please!

2007-03-26 01:31:25 · 2 answers · asked by sunny 4

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Help with this physics formula?

So the energy of a photon is :

E = (h c )/ f

E: energy
h: constant 6.63 * 10^(-34)
C: constant 3 * 10^(8)
f: wavelength

thus if we have 75 kV of E

f = hc / E = 6.63 * 10 ^(-34) * 3 * 10^(8)
--------------------------------------
75 * 10^3 * 1.6 * 10^(-19)

Then the answer should be 1.6575 * 10^(-11)

But the solution is 16.6pm

I dont get it!!

2007-03-26 01:08:01 · 6 answers · asked by sunny 4

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IYPT Questions: What is the minimum speed needed to pull an object attached to a rope over a water surface?

What is the minimum speed needed to pull an object attached to a rope over a water surface so that is does not sink. Investigate the relevant parameters experimentally and theoretically.

2007-03-26 01:06:42 · 1 answers · asked by jammal hines 1

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If isotope of barium has atomic # of 56 & atomic mass of 130 (elecrtically neutral). How many protons it has?

How many protons does it possess? How many electrons? How many neutrons? How many nucleons? Thease are Radilogical x-ray Physics questions. Please explain your answers.

2007-03-26 01:02:50 · 5 answers · asked by Student #07 1

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Momentum and explosion?

Three smooth stones A, B, C are initially at rest, in contact with each other on the smooth surface of a frozen lake. The masses of stones are A = 800g B = 600g and C = 250g and the coefficient of sliding friction between the stones and the ice is 0.0250. An explosion between the stones causes them to fly apart across the surface of the ice. Stone A flies off due North
with an initial speed 2.40 ms^-1. Stone B flies off due east with an initial speed of 3.60 ms^-1.

Q1 Calculate the speed and direction of motion of stone C
immediately after the explosion.
I got v = 11.56 ms^-1 and direction = 41.67 degrees.
I reckon that is south west? Any ideas.

Q2 If 10 per cent of the total energy of the explosion was converted to kinetic energy of the stones, what was the total energy released in the explosion
Q3 Show all the forces acting on stone A when sliding on
the ice after the explosion. How far does it travel before it
comes to rest. g = 9.81ms^-2

2007-03-26 00:58:29 · 1 answers · asked by TJ 2

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why are solids and liquids hard to compress?

please be specific with the answer and make it short. thanks a lot.

2007-03-26 00:57:28 · 7 answers · asked by princess_J 1

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light is a electro magnetic(EM)wave so it has electric nd magnetic particles but y wont it deflect in EM field

as it containg electric and magnetic particles it should deflect in a EM field as when it travels in the EM field the -ve or +ve electric or magnetic particles attract to the -ve or +ve particles of the EM field-this reason is true i suppose,but still its a fact that light does not deflect in a EM field.This is the same with x ray they to r electro magnetic waves but do not deflect in an EM field.

2007-03-26 00:55:26 · 1 answers · asked by Deepank 2

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Why are eskimo's never very cold?

2007-03-26 00:51:59 · 5 answers · asked by Tantric M 1

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explain the zone theory?

2007-03-26 00:43:11 · 1 answers · asked by sanjib m 1

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who are using the scanning electron microscope and what is the phycics theory behind this invention?

2007-03-26 00:11:45 · 2 answers · asked by akira a 1

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energy, photon?

Suppose all the energy from a 100 watt light bulb came in the form of photons with wavelength of 600 nm.

a. Calculate the energy of a single photon with wavelengh 600 nm.

b. How many 600 nm photons must be emitted each second to account for

all the light from this 100 watt light bulb?

2007-03-26 00:00:05 · 3 answers · asked by Unexpected 1

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Physics question :S?

Bob has a mass of 100kg has been lassoed by 5 different people, each of them whom has attached a rope to him. The first guy is pulling north with a force of 200N. The second guy is pulling south with a force at 150N. The third is pulling north at 300N. The fourth pulling east at 250N. And the last pulling west at 250N.
What is the acceleration of Bob?

I'm really struggling with this.

I have to get all the help I can.

Greatly appreciated.

2007-03-25 23:55:07 · 1 answers · asked by Hmmmmm 3

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how do you calculate work? (physics)?

I know that there are two formulas to calculate work

one is an integration of force with respect to displacement
W = 1/2mv^2 - 1/2 mv^2

the other is the dot product of F and displacement.
W = F dot d

what's the difference between these two.? i mean how do you know which one to use? I thought, if the force is not constant I use the first method, and if it is i use the second... if this right/???

2007-03-25 23:45:37 · 7 answers · asked by bluebirdsrule 1

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Physics help?!?

I'm having trouble understanding this question and the method to do it.

A rider is thrown out of a horse and sulky. The horse continues to pull with a force of 20000N. The sulky has mass of 100kg. The rider has a mass of 60kg, is hanging on to the back of the sulky dragging on the ground. Friction forces total 19,200N.
Determine the acceleration of the sulky.

Please help.

It will be appreciated.

2007-03-25 23:31:06 · 2 answers · asked by Hmmmmm 3

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A solid sphere of radius r has moment of inertia I about its axis.....?

A solid sphere of radius r has moment of inertia I about its geometrical axis. If it is melted into a disc of radius r and thickness t. If its moment of inertia about the tangential axis( which is perpendicular to plane of the disc), is also equal to I, then the value of r is equal to : a) (2/(15^1/2))*R
b) (2/(5^1/2))*R
c) (3/(15^1/2))*R
d) ( (3/15)^1/2)*R
Please explain.

2007-03-25 23:26:09 · 2 answers · asked by Nikhil 2

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