Physics - June 2007

1) Does einsteins explanation of the photoelectric effect invalidate Young's explanation of the double-slit experiment? Explain.
2) Consider one of the many electrons on the tip of your nose. If someone looks at it, will its motion be altered? How about if it is looked at with one eye closed? With two eyes crossed? Does Heisenbergs uncertainty principle apply here?
3) If the behavior of a system for some period of time is measured exactly and is understood, does it follow that in the future behavior of that system can be exactly predicted? (Is there a distinction between measurable and predictable qualities?)

2007-06-25 05:07:06 · 3 answers · asked by Anonymous

Five resistors with resistance R1 = 2.00 ohm, R2 = 2.00 ohm, R3 = 3.00 ohm, R4 = 7.00 ohm, R5 = 4.00 ohm, are connected to a battery with emf = 9.00 V as shown in the figure.

1- What is the current in resistor R1?
2-What is the current in resistor R2?
3-What is the current in resistor R3?
4-What is the current in resistor R4? 5-
5-What is the current in resistor R5?
6-What is the potential difference between the points P and P'?

the figure : http://www5.0zz0.com/2007/06/25/09/15627721.gif

2007-06-25 04:54:38 · 2 answers · asked by Anonymous

2007-06-25 04:50:51 · 7 answers · asked by Anonymous

2007-06-25 04:40:11 · 7 answers · asked by snowprincess 1

Two parallel lead cylindrical wires have diameters D=4mm
and the distance between their axes is L=5mm.
Both wires are in superconductive state.
The wires carry currents 60A each in opposite directions.

What is the force of magnetic relpulsion F between
the wires per unit length (per 1 meter)?

Notes:
(a) Meissner effect: magnetic field does penetrate inside
superconductive lead.

(b) Easy-to-use magnetic force calculator can be found here:
http://hyperphysics.phy-astr.gsu.edu/hbase/magnetic/wirfor.html

2007-06-25 04:38:24 · 1 answers · asked by Alexander 6

A battery (9.284 V) is connected to a resistor (9856 ohms) and a capacitor (15.73 mcF). Calculate the charge Q(t) on the capacitor if initially the stored charge was zero. Show your work please, if you want to be chosen a best answer.

2007-06-25 04:37:34 · 3 answers · asked by Nate-dawg 2

Would anyone be able to answer this physics question for me. It is not a homework question, I had a gcse in physics today and it came up and I wanna know whether I got the right answer:

Getting solar panels installed costs £10000. It produces 0.2kW (on average) It has a lifetime of 200000 hours. How much does each kWh of elecricity cost?

Cheers, dom

2007-06-25 04:33:30 · 7 answers · asked by footie089 1

In physics, specifically relativity and Special Relativity, why do we assume the speed of light to be constant (for eg. in Einstein's formula E=mc^2 "c" is the speed of light which is considered constant) while also knowing that the speed of light changes when it passes from one medium to another (eg. water to air).

2007-06-25 04:29:18 · 6 answers · asked by Anonymous

tell about shocks caused by ac and dc?
genuine answers plz

2007-06-25 04:24:56 · 13 answers · asked by Anonymous

2007-06-25 04:22:42 · 7 answers · asked by Anonymous

A skater is initially spinning at a rate of 17.9 rad/s with a rotational inertia of 2.85 kgm2 when her arms are extended. What is her angular velocity after she pulls her arms in and reduces her rotational inertia to 1.58 kgm2?

_____rad/sec

2007-06-25 04:08:26 · 2 answers · asked by terra_flare_aqua_ciel 1

A 3.0 m diameter merry-go-round with a mass of 250 kg is spinning at 20 rpm. John runs tangent to the merry-go-round at 5.0 m/s in the same direction that it is turning and jumps onto the outer edge. John's mass is 30 kg. What is the merry-go-round's angular velocity, in rpm, after John jumps on?

2007-06-25 04:05:43 · 1 answers · asked by Anonymous

2007-06-25 03:48:55 · 7 answers · asked by Anonymous

(continuation)
of the gas. Use dimensional analysis to determine the exponents x, y, and z in the formula:
v= CP^xp^yV^z
where C is a dimensionless constant. Incidentally, the mks units of pressure are kilograms per meter per second squared (kg/ms^2).

2007-06-25 02:35:57 · 2 answers · asked by Anonymous

newton's 3rd law of motions states that there is an equal and opposite reaction to every action.
Which is not an illustration of this law?
1. a rifle recoils after firing
2. a duck pushes water backwards in order to move forward.
3. a pendulum bob swings first forward, then backwards.
4. when a boy jumps forward off a stationary skateboard, the skateboard goes backward.

2007-06-25 02:15:54 · 10 answers · asked by Stormy Knight 1

2007-06-25 02:12:44 · 2 answers · asked by shyboy 1

A lunar landing craft descends vertically towards the surface of the moon with a constant speed of 2.0m/s. The craft and crew have a total mass of 15,000kg. Assume that acceleration due to gravity on the moon is 1.6m/s^2.
(a) During the first part of the decent, the upward thrust of the rocket engines is 24,000N. Show that this results in the craft moving at a constant speed.
(b) The upward thrust of the engine is increased to 25,500N for the loast 18 seconds of the descent.
i. Calculate the deceleration of the craft during this time
ii. What is the speed of the craft just before it lands?
iii. How far is the craft above the surface of the moon when the engine thrust is increased to 25,500N?

2007-06-25 02:10:54 · 2 answers · asked by Stormy Knight 1

1. a meter is about 3.28 feet and a hectare is 10,000 square meters. find the area of a rectangular lot whose length is 2.500 feet and whose width is 1,750 feet in (a) square ft (b) square meters (c) hectares.

2. the speed of light in free space is equal to 2.998 x 10 to the 8 m/s. express this an (a) ft/s miles per hr (b) km/hr.

3. mercury freezes at -40 degrees C. what is the temperature in (a) fahrenheit scale? (b) kelvin scale.

4. in a certain experiment the circumference and radius of a disc were measured to be 21.95 cm and 3.51 cm, respectively. what is the computed value of pi? solve for the percent error.

5. express the angular speed of minute hand of an electric clock in (a) rev/sec (b) rad/sec (c) deg/sec.

2007-06-25 01:52:46 · 4 answers · asked by just 1

2007-06-25 01:19:31 · 3 answers · asked by mamarj 1

laws of motion.

2007-06-25 00:24:47 · 6 answers · asked by LEE 1

2007-06-25 00:21:28 · 13 answers · asked by JOHN M 3

2007-06-24 23:33:31 · 4 answers · asked by JOHN M 3

it should be about physics...thank you

2007-06-24 23:14:35 · 3 answers · asked by Anonymous

With the exception to cost, what are the problems or limitations with electro-magnetic trains?

2007-06-24 23:11:23 · 5 answers · asked by Anonymous

what would happen if everyone on the earth were to jump at the same time.

2007-06-24 23:10:15 · 8 answers · asked by Aaron S 1

Are there any markings to help do so?

2007-06-24 22:54:10 · 4 answers · asked by Wambua Daudi 1

Is nuclear power safe to use for generating electricety?

2007-06-24 22:12:41 · 9 answers · asked by deanismay 1

Also, why does the current changes direction when the movement of the conductor is changed?
What causes the electrons in the metal conductor to move, which causes the current to be set up?
What is the exact source of the induced e.m.f. in the circuit?

2007-06-24 22:06:19 · 2 answers · asked by noob 1

2007-06-24 19:23:19 · 4 answers · asked by Anonymous

how do I hook up the following:
V_in -- [series] -->
hi-pass filter -- [series] -->
low-pass filter -- [parallel] -->
(1) hi-pass / tweeter
(2) lo-pass / woofer

How would this look if I were to draw the circuit? Neither the textbook nor any web sites help

2007-06-24 18:01:51 · 2 answers · asked by Anonymous