Physics - November 2007

links -time- clock-use - not used-

2007-11-30 03:26:54 · 13 answers · asked by Anonymous

Zinc selenide has a band gap of 2.58 eV. Over what range of wavelengths of visible light is it transparent?

2007-11-30 03:06:20 · 4 answers · asked by FER 2

2007-11-30 03:04:19 · 1 answers · asked by Anonymous

The day and night are divided into 24 hours and hour in 60 minutes and minute in 60seconds.Can these be measured in meric system.And why a minute is equal to 60seconds.?

2007-11-30 02:44:28 · 9 answers · asked by krishjoshi 1

A 2.3 kg stone is whirled at 55 rpm in a circle at the end of a wire of length 1.2 meters. If the plane of the circle is vertical, calculate

(1) the tension in the wire at the top of the cycle
(2) at the bottom of the cycle

2007-11-30 02:20:21 · 2 answers · asked by labelapark 6

2007-11-30 01:44:19 · 3 answers · asked by Anonymous

2007-11-30 01:38:28 · 1 answers · asked by landroval88 1

Ive always wanted to know, if a fly was like, in a car, does it have to work really hard to keep up with the speed of the car or does it just hover like it was in a stationary room. I used to think that it would have to work really hard because the car is moving really fast, and we dont work hard because we are sitting down on seats. I hope it can be solved!?

2007-11-30 01:30:34 · 19 answers · asked by Niallo! 3

sunglasses that permit only the passage of light that's

A. polarized in a vertical plane.
B. dispersed in a vertical plane.
C. dispersed in a spherical plane.
D. polarized in a horizontal plane.

2007-11-30 01:29:14 · 1 answers · asked by Anonymous

A 2.86 kg block starts from rest at the top of a 30° incline and accelerates uniformly down the incline, moving 1.85 m in 1.70 s.

(a) Find the magnitude of the acceleration of the block.
m/s2
(b) Find the coefficient of kinetic friction between the block and the incline.

(c) Find the magnitude of the frictional force acting on the block.
N
(d) Find the speed of the block after it has slid a distance 1.85 m.
m/s

2007-11-30 01:26:32 · 2 answers · asked by Anonymous

The coefficient of static friction between the 3.01 kg crate and the = 26° incline shown below is 0.300. What is the magnitude of the minimum force, F, that must be applied to the crate perpendicularly to the incline to prevent the crate from sliding down the incline?

2007-11-30 01:14:04 · 1 answers · asked by Anonymous

2007-11-30 01:04:51 · 1 answers · asked by Anonymous

A box slides down a 31° ramp with an acceleration of 1.20 m/s2. Determine the coefficient of kinetic friction between the box and the ramp.

2007-11-30 00:52:27 · 1 answers · asked by Anonymous

Hi
I am a Physics student and recently read about Bose-Einstein condensation. A couple of questions came to me that you might be able to answer.
1. If an object approaches absolute zero will it gradualy start to disappear due to the fat that there will be a reduced number of photon emisions due to reduced transitions to different energy levels.
2. Does an object have a reduced or no mass at or approaching absolute zero. Does this mean that hotter objects have greater mass than cold objects.

Answers to these questions would be much appreciated.

Many thanks

dba

2007-11-29 22:12:08 · 4 answers · asked by Anonymous

Assuming one were to somehow bypass the safety latch in some way, what would happen if the microwave were to be run with the door open.

I know that it emits radiation to heat the food, but would this handy device emit radiation into the room?

Safe levels? Hazardous?

And NO - I WILL ABSOLUTELY *NEVER* EVER DO THIS
I'm not stupid, not psycho, and not suicidal!
I'm simply curious, and certainly am not going to attempt it myself. Ever.

So does anyone know?

2007-11-29 18:20:18 · 4 answers · asked by tryandfindus 5

please help me. its for physics test tomorrow.

2007-11-29 18:16:02 · 3 answers · asked by dreamer 2

V#1 +V#2 = V#3

Where:
V#1 is my velocity
V#2 is the speed of light (from the flashlight)
V#3 is the combined speed of the light and my speeds


since velocity is cumulative (i.e. throwing a baseball out of your car, while your car is going 100 mph would mean the ball would be traveling at least 100 mph as it left your hand depending on how hard you threw it.) wouldn't the light be traveling just faster than the theoretical value we have determined as the speed of light?

2007-11-29 17:30:38 · 4 answers · asked by Null 2

really nid this asap..plsss...and thnk u^^

2007-11-29 17:15:56 · 5 answers · asked by nid_help 1

I'm actually making a motor... for our physics project...
but I've got a problem about it.. and I need answers immediately.. as soon as possible...

The motor moves fast because of the flow of current.. so I need to reduce its flow to lessen its turn...

the motor's shaft moves as fast as the electric fan moves... so I need to lessen it.. what can I use? and please also explain how will it help me.. thanks!!!

2007-11-29 16:45:24 · 15 answers · asked by ~§~ 3

what can a graph of force vs. time tell you

2007-11-29 16:35:21 · 4 answers · asked by Joe T 1

An 8kg ball is suspended .6m at the end of a horizontal bar which is attached to a vertical pole. The horizontal bar extends .8 meters from the top of the vertical pole. From the top of the pole, there is a second string that extends down to the ball at a 30 degree angle. The pole is rotating at a constant speed such that the linear velocity of the mass is 2.3 m/s. What is the tension of the vertical wire? Please show steps and formulas used to get solution.

2007-11-29 16:22:56 · 1 answers · asked by Anonymous

we can add almost anything to inside of metal can to hold washers, but the objective is to make it roll as fast as possible down ramp.... HELP!

2007-11-29 16:10:38 · 4 answers · asked by Isabel 2

If you could show your work, that would be great!
A football punter wants to kick the ball so that it hits the ground 50 meters from where it is kicked and so that the ball is in the air 4 seconds. At what angle and with what initial speed should the ball be kicked? Assume that the ball leaves the kicker's foot from and elevation of 1 meter.

2007-11-29 16:08:24 · 1 answers · asked by Anonymous

A 17 kg crate is to be pulled a distance of 20 m requiring 1210 J of work being done. If the job is done by attaching a rope, and pulling with a force of 75 N, at what angle is the rope held?

2007-11-29 15:19:14 · 1 answers · asked by Anonymous

...left end and is completely horizontal. The second rope is attached to the left end and is completely vertical. The third rope is attached to the right end and makes an angle of 40.0 degrees with the horizontal. What is the tension in these ropes when a 700N person stands 0.5 meters from the left end?

2007-11-29 15:17:15 · 1 answers · asked by Anonymous

If sound it spread evenly through the same medium, and it will still go through a different one at a different speed, then wouldn't that mean that the sound of every single thing doesn't go away.. the vibrations are just so small that the human ear cannot pick it up.
The reason I ask is that EVENTUALLY that would mean that the sound would continually build up and I think that is the High-Pitched noise that people hear when there is supposed silence.

At least... when I don't hear anything else in particular I hear a high-pitched noise....

2007-11-29 15:05:24 · 3 answers · asked by Brodan Victa 3

Two blocks of respective masses m1=0.35 kg and m2=7.5 kg stand without motion on a frictionless horizontal table. A spring is compressed between the two blocks, but the blocks remain motionless because they are tied to each other by a cord. The masses of the spring and the cord are not negligible compared to the masses of the blocks. Once the system is set up, the cord is burned by a match and the blocks are pushed apart by the spring. Once the spring is completely relaxed, it detaches from the m1 block, and the blocks continue to move away from each other at respective speeds v1 and v2. Given m1=0.35 kg, m2= 7.5 kg, v2= 5.9 m/s but v1 is not given. How much energy was stored in the compressed spring before the cord was burned?

2007-11-29 15:05:10 · 1 answers · asked by Ron108 1

Calculate the frequency of a sound wave in helium if its displacement amplitude in helium is 3.9 *10^-10 m and the pressure amplitude is 8.8 *10^-5 N/m^2. The density of helium is 0.48 kg/m^3 and the speed of sound in helium is 291. 6 m/s. Answer in Hz.

2007-11-29 14:51:40 · 1 answers · asked by Ron108 1

mass is 325 N
force is 425 N
angle is 35.2 degrees

needing to find the coefficent of the kinetic friction aka "myoo-k"

2007-11-29 14:37:34 · 1 answers · asked by MINAL 1

In a hot day’s race, a bicyclist consumes 8 liters of water over the span of four hours.
Let us assume that 80% of his energy goes into evaporating this water as sweat. (This is
not a bad approximation, because the mechanical efficiency of a bicycle rider is only
about 20%, with the rest of the energy consumed going into heat.) How much total
energy, in kcal, did the rider use during the race?

2007-11-29 14:10:30 · 2 answers · asked by Anonymous