Physics - November 2007

Other than a change in humidity/tempterature, how in the name of thermodynamics can guitar strings go sharp (i.e. increase their tension)?

2007-11-16 10:07:08 · 5 answers · asked by Orpheus Rising 5

Assume a 9 kg bowling ball moving at 1 m/s bounces off a spring at the same speed that it had before bouncing.

(a) What is its momentum of recoil? (kg·m/s)

(b) What is its change in momentum? (Hint: What is the change in temperature when something goes from 1 degree to -1 degree?) (kg·m/s)

(c) If the interaction with the spring occurs in 0.5 s, calculate the average force the spring exerts on it. (N)

Good Luck!

2007-11-16 10:06:13 · 5 answers · asked by gmfron 1

A 52.0 kg crate rests on a level floor at a shipping dock. The coefficients of static and kinetic friction are 0.700 and 0.440, respectively.

(a) What horizontal pushing force is required to just start the crate moving?
_ N

(b) What horizontal pushing force is required to slide the crate across the dock at a constant speed?
_N

2007-11-16 10:04:38 · 4 answers · asked by Anonymous

The parachute on a race car that weighs 7250 N opens at the end of a quarter-mile run when the car is traveling 45 m/s. What total retarding force must be supplied by the parachute to stop the car in a distance of 1100 m?
_N

2007-11-16 10:02:04 · 1 answers · asked by Anonymous

. A particle starts with velocity 30m/s& has constant deceleration of 10m/s^2.
find velocity after 1 sec, (b) time when velocity=0
(c) time taken to reach velocity of -30m/s.

2007-11-16 09:45:25 · 1 answers · asked by sophie 2

i have a problem on my hw about vectors and the addition of them with direction and such

it says add:
63mph, 45 degrees north of west << i get that
54 mph, due northeast<< wat the heck does due mean?

i need a degree like 45 or 90 or something but why do some problems use due? i have not a clue wat due means!

2007-11-16 09:39:14 · 4 answers · asked by Wanda McAlias 2

1.A negative acceleartion might mean that an object is speeding up while going in the __________ direction.
2. Horizontal or diagonal lines on a position-tine graph indicate that no ____________ occurs.
3. When velocity is negative and acceleration is positive an object is_____________________.
4. An object that is slowing down in the ____________ direction has a negative accelaration.
5. A curvilinear line on a ____________- time graph represents uniform accelerated motion.

2007-11-16 09:13:59 · 1 answers · asked by Whitney 1

OK you geniuses. Here is one in the field of celestial mechanics. Let's see who can figure out the correct answer to this one. (Totally hypothetical of course.) Good luck.

If the Earth was to suddenly double in size in both its diameter and it's density, which of the following things would occur as a result?

A) The speed of it's orbit around the Sun would slow down.
B) The speed of it's orbit around the Sun would increase.
C) The Earth's distant to the Sun would decrease due to gravity.
D) The Earth's distance to the sun would increase due to angular momentum.
E) The correct answer is actually A+C.
F) The correct answer is actually A+D.
G) The correct answer is actually B+C.
H) The correct answer is actually B+D.

(PS...Let's forget about the Moon for the sake of the question.)

2007-11-16 09:05:02 · 3 answers · asked by Becky 3

y is measured in feet and t is measured in seconds.

Find the acceleration of the particle when t=3

Please show all steps

2007-11-16 08:51:56 · 1 answers · asked by Anonymous

A solid cylindrical disk has a radius of 0.17 m. It is mounted to an axle that is perpendicular to the circular end of the disk at its center. When a 45 N force is applied tangentially to the disk, perpendicular to the radius, the disk acquires an angular acceleration of 90 rad/s2. What is the mass of the disk

2007-11-16 08:39:01 · 1 answers · asked by Anonymous

Are there any geeks out there planning to celebrate the day before the Hadron Collider is turned on in May 2007 as if it were the last day on Earth?

2007-11-16 08:30:39 · 3 answers · asked by Jack X 2

Given:
-height of ramp
-length of ramp
-mass of hoop
-inner and outer radius of hoop
-frictionless

Would my notes acurately predict the time in an ideal-frictionless situation (this is a physics 101 course):


Find Time:

Find α:
Using T=Iα
I=(1/2)M(R^2+R^2)
T=Mg(sinφ)R
Mg(sinφ)R=((1/2)M(R^2+R^2))α
(φ=slope of ramp)
(R's refer to inner
and outer radii)

find θ
d=θR
(d=top of ramp)
(R is outer hoop radius)

find time
θ=(1/2)αt^2

---------
Find ω_final
(ω_f)^2=(ω_i)^2+2αθ

Find final velocity
v_f=(ω_f)*R
(R is outer hoop radius)

2007-11-16 08:28:30 · 1 answers · asked by RogerDodger 1

when forming they reach sufficient mass and ignite(fusion)
eg our sun, and blow the rest of the matter out. what then stops that process when giant or super giant stars are forming???

2007-11-16 08:08:44 · 6 answers · asked by Anonymous

If you weighed a beaker of water on a scale, then added an object to it that was submerged in the water but did not touch the bottom of the beaker, would the scale reading increase, decrease or stay the same. Explain why

2007-11-16 06:50:39 · 8 answers · asked by Anonymous

Thanks!

2007-11-16 06:24:46 · 5 answers · asked by Neuroscience2321 2

A fishing pole is 2 m long and inclined to a horizontal at an angle of 20 degrees. What's the torque (t) exerted by the fish about an axis perpendicular to the page and passing through the hand of the person holding the pole?

2007-11-16 06:07:50 · 3 answers · asked by Captain Whiskerboy Litterbox 3

can a photovoltaic produce current forever as long as it has light striking it? or does it at some point run out of electrons?

2007-11-16 05:30:52 · 2 answers · asked by Anonymous

I mean with all the cell phones, Wi Fi routers, remote car door unlockers, garage door openers and radio stations, it seems there must be limit to how many frequencies can exist.
Perhaps when we use up the last one, something weird might happen to our brain waves or something.

2007-11-16 05:26:14 · 6 answers · asked by Anonymous

Figure P9.81 shows a water tank with a valve at the bottom. If this valve is opened, what is the maximum height attained by the water stream coming out of the right side of the tank? Assume that h = 9.0 m, L = 1.50 m, and = 35° and that the cross-sectional area at A is very large compared with that at B.
m (above the level where the water emerges)

http://smg.photobucket.com/albums/v296/operaprincess315/?action=view¤t=p9_81.gif

2007-11-16 05:00:22 · 2 answers · asked by Butterfly <3 2

Newton’s 2nd law says that if there is no net force exerted on a system no acceleration is possible does it follow from this that no change in momentum can occur. Why or why not

2007-11-16 04:50:22 · 1 answers · asked by blond_n_punk 2

In a particle accelerator, an alpha particle with a mass of 6.64 x 10– 27 kg is moving with a speed of 2.50 ´ 107 m/s. It is moving perpendicularly through a magnetic field of intensity 0.150 T. Using appropriate equations and method, find the radius of curvature of its path.


My question is what does the 2.5 ` mean? Ive been looking through my books and havent seen it mentioned anywhere.

2007-11-16 04:47:54 · 2 answers · asked by Anonymous

Light of wavelength 598 nm illuminates a single 0.77 mm wide slit. At what distance from the slit should a screen be placed if the first minimum in the diffraction pattern is to be 2.03 mm from the central maximum?

2.614 m, i got this right

What is the width of the central maximum?

no idea i cant seem to get this answer any suggestions...?

2007-11-16 04:06:44 · 2 answers · asked by meeh 1

whenever there's change in kinetic energy, there's change in potential energy ? ..

My problem is involving a horizontal force is acting on a horizontally moving particle, then I am asked to find the potential energy U ... how can such particle ( moving horizontally ) have a potential energy ? ...

As I know, a potential energy means mass x g x y .... in above problem there's no change in y ( height ) ....

Please help me figure this point out ... thank you very much

2007-11-16 03:53:40 · 5 answers · asked by Learner 1

Ok, I have kind of bad eyesight...

The other day, I was looking in a mirror, and noticed that things that are far away are still blurry.

I turned around and looked at the objects directly, and noticed that when I look in the mirror, they are just as blurry as looking at them directly.

Why is this? It seems like since I am so close to the mirror, and am seeing it up close, that the objects wouldn't be blurry...

Thank you!

2007-11-16 02:56:53 · 11 answers · asked by Dork with Questions 2

For example, when something is red, it's absorbing all the colors of light, besides red.

So does that mean water is absorbing all the colors of light, or none at all?

Thank you.

2007-11-16 02:49:01 · 4 answers · asked by Dork with Questions 2

The drawing shows two graphs that represent a transverse wave on a string. The wave is moving in the +x direction. Using the information contained in these graphs, write the mathematical expression (similar to Equation 16.3 or 16.4) for the wave. (Answer in terms of t and x. Assume standard units.)


http://img85.imageshack.us/img85/8610/1626altlo7.gif

2007-11-16 02:47:20 · 1 answers · asked by Anonymous

I vaguely remember in school (god i feel old) my physics teacher telling us that the universe is expanding or something. And he also told us something about it making a noise like a racing car (although that may have been something else)

Anyway is this a theory or is there evidence for it?

2007-11-16 02:29:08 · 8 answers · asked by Lynsey W 1

Let's say I take a piece of paper and place it in the middle of the universe, stationary. Everything else is smaller than this piece of paper. Would the paper exert gravity on the smaller objects? If so, how small would the objects have to be, or how big would the piece of paper have to be to have them rotate around the paper? Does an object have to be a specific shape to exert gravity or rotate a certain speed? This is an honest question.

2007-11-16 01:40:45 · 12 answers · asked by tcjstn 4

2007-11-16 01:21:30 · 5 answers · asked by Anonymous

a cart moving on smooth horizontal track without any external force.rain is falling with a velocity u m/s at an angle theta (clockwise) with the vertical.rain drops are collected in the car at the rate of m kg/s.if the initial mass of the car is M and velocity V(towards right) then find its velocity after time T

2007-11-16 01:04:44 · 1 answers · asked by Anonymous