Physics - October 2007

--that is initally at rest.

(b) The sled and person coast 30.0 m on level snow before coming to rest. What is the coefficient of kinetic friction between the sled and the snow?

2007-10-09 04:59:20 · 3 answers · asked by Anonymous

--rest.
The lumberjack runs to the other end of the log, attaining a velocity of +2.8 m/s relative to the shore, and then hops onto an identical floating log that is initially at rest. Neglect any friction and resistance between the logs and the water.

(b) Determine the velocity of the second log if the lumberjack comes to rest on it.

2007-10-09 04:58:21 · 1 answers · asked by Anonymous

plzz.. define each of them .. it's important ...

2007-10-09 04:39:12 · 2 answers · asked by jhay ar 1

take the case of1. free fall and also of 2.an object moving on a surface and 3.an object moving in space etc.... and as many as possible....
some say dependent while some say independent . I'm confused..........................
I just know that acceleration is inversely proportional to mass................

2007-10-09 04:08:29 · 6 answers · asked by Anonymous

**PLEASE NOTE: I DO NOT WANT THE ANSWER**
I just want to know how to work it out =]

1) A student wants to find out the efficiency of a stereo system, rated at 20 watts sound output. She buys some batteries, which store 400,000 joules of energy of chemical energy. When the new batteries are put into the stereo, and its switched on to play a tape, the batteries run out after 5 hours.

a) How much energy has the stereo usefully given out?

b) What is the efficiency of the tape recorder

In class we learnt that
Efficiency = Useful energy out divided by total energy in



The last question is:
If the stereo is used on the radio setting, would you expect the batteries to last longer?

I don’t know if it takes more power to power the motor to spin the CD and the laser to read it or if it takes more power to receive the signal from the radio station???


Please help me

Thanks for your time

2007-10-09 04:06:00 · 1 answers · asked by Anonymous

I mean whenever a mass is placed in spacetime it bends it causing gravitation anf time dialation around it right???

even magnetic field and electric field represent curved spacetime but why is it that magnetic fiel of a magnet attarcts or responds only to MAGNETIC substaneces? if its merely a curvature of spacetime all the "masses" should follow it and on nearing it should strike onto it..but its not quite so...
2)AND magnet repels like poles how is that..when its just a curve of space??? does space decide what type of matter sould follow it and in what directio0mn and manner?????


plz give full explanation..

fast!!

2007-10-09 04:05:00 · 3 answers · asked by Swapnil B 2

2007-10-09 03:42:13 · 3 answers · asked by Charlene 2

2007-10-09 03:26:09 · 6 answers · asked by Anonymous

pls, help.. i'm confuse... thanks

2007-10-09 03:09:05 · 4 answers · asked by jhenleen 1

the water is half filled with ice....it's on a stove....what temprature would make the water reach 9 or 10 and how long would it take??

2007-10-09 02:40:40 · 2 answers · asked by Anonymous

I was looking scientific prove of a higher power to better understand it's nature,and was told Galileo had done some work on the subject

2007-10-09 02:19:32 · 8 answers · asked by armbar60805 1

You are driving south on a highway at 25m/s (approx. 55mi/h) in a snowstorm. When you last stopped, you notice that the snow was coming down vertically, but it is passing the windows of the moving car at an angle of 30 degrees to the horizontal. Estimate the speed of the snowflakes relative to the car and relative to the ground.

2007-10-09 02:18:04 · 1 answers · asked by Hu-Li X 1

Hi,
Does anyone know if there is such a thing as a Mono-Pole Magnet, and if so how do you make one?
Serious answers only please.
Many thanks.....

2007-10-09 02:13:03 · 9 answers · asked by darrenleedavis 1

I know to find absorbance the equation is absorbance= 2=log%T.

But, how do I solve THIS equation?
%T= ?

(basically I forgot how to take the inverse log or whatever)

2007-10-09 01:42:07 · 1 answers · asked by I_color_outside_the_lines 4

With a huge universe that hasnt all been discovered yet it is very possible for somthing to be faster then the speed of light.
I mean There is somthing faster then the speed of light. A black hole can suck up light which leaves light slow compared to it. If a black hole can suck up light then is it possible to pull the light closer to where you are and find out what the current state is? May seem impossible but as we know Black holes have a range limit of what it sucks in. If a minature star can be accellerated to the point of collapsing with a supernova then it can be possible to steal the light as in like pulling a string.
If that string can be pulled time will be accellerated between the Hole and the light of the planet or star. In which I think is a wormhole? Do you think that could be possible of all means in any way at all? Which such a huge universe? Think of all the possiblities of things like that happening in the huge universe.

2007-10-09 00:39:55 · 21 answers · asked by Anonymous

anyone know?

2007-10-08 21:25:10 · 2 answers · asked by Mad Hatter's Apprentice 3

hey
i have a test tomorrow on problems about acceleration and velociy and stuff and i have no clue how to do this stuff :( can someone please help me and explain?

a plan starting from rest at one end of a runway, undergoes a constant accerleation of 1.6 m/s2 for a distance of 1600m before takeoff. what is its speed upon takeoff? what is the time required for takeoff?

i tried plugging this in..
do i use the acceleration formula?
but switch it around so the time variable is alone?
omgosh please help and explain

2007-10-08 20:46:58 · 9 answers · asked by cocomademoiselle 5

I have a HPS lamp which emit much (about 80%) of its light with a wavelength, between 550nm and 620nm, I want to know if one can use a colour filter to change colour of the light emitted, blue (or a value between 420nm and 500nm) without loosing to much of the intensity of the light. If a filter is just filtering the light then I suppose most of the light, above the 500nm wavelength will be lost...true? I do not know how this works but if it is just changing the colour it would be great to change the light blue with almost the same lumens.

2007-10-08 20:40:27 · 2 answers · asked by matroosje 2

Something to do with flying close to the ground at high speeds?

2007-10-08 17:36:15 · 4 answers · asked by Anonymous

This question is in regards to Radiology physics. Here a few more. Find frequency for 2.4 Mev and 35 ev. I would like to have step by step instructions please. I'm having trouble figuring out what needs to be converted, if any. Thanks

2007-10-08 17:33:50 · 4 answers · asked by Anonymous

One of Roengent's early observations was that x-rays are not deflected by the magnetic field. What does this indicate about the nature of x-rays?

2007-10-08 17:31:27 · 1 answers · asked by Anonymous

Car Accident
You are the juror of a case involving a drunken driver whose 1049.0 kg sports car ran into a stationary 2092.0 kg station wagon stopped at a red traffic light. The cars stuck together and slid with locked wheels for 10.0 m before coming to rest. The coefficient of sliding friction on the dry road was 0.9. Estimate the speed of the sports car when it hit the station wagon.

I only have one try left on this problem..Please help

2007-10-08 17:22:26 · 2 answers · asked by Anonymous

Self explanatory. Does quantum physics apply in real life?

2007-10-08 17:05:34 · 2 answers · asked by pikid3141 2

Why don't magnetic wave forms take up space... I can understand why sound waves will not take up space because of the way they move particles already in space but what about radio or other magnetic waves?

2007-10-08 16:33:51 · 3 answers · asked by jack 6

The drawing shows a circus clown who weighs 960 N. The coefficient of static friction between the clown's feet and the ground is 0.52. He pulls vertically downward on a rope that passes around three pulleys and is tied around his feet. What is the minimum pulling force that the clown must exert to yank his feet out from under himself?

like, i can't even find a place to start. it is 11:30 at night and im tired and just want to finish this homework and go to sleep. please, Please help me. you don't even have to fully explain your work. i just need help.

thank you so much!

2007-10-08 16:31:39 · 3 answers · asked by Elizabeth 3

The steel I-beam is basically a crane with a triangle it is liftling. the triangle is isosceles with two 70 degree angles and one 40 degree angle. it has a weight of 9.30 kN and is being lifted at a constant velocity. What is the tension in each cable attached to its ends?


i know that the velocity is constant so a=0, and the sum of the forces =0. and i know mg = 9300 N, not 9300*9.8 m/s^2. You do not multiply by 9.8, since you are given the weight, not the mass.

so....

t1~tention 1
t2~tention 2
in the y dirrection: t1 sin theda1 + t2 sin theda2=0
in the x dirrection, t1 cos theda1 + t2 cos theda2=0

i understand that if you make a triangle, t1 is the hypotenuse, t1y=1/2 fg, and t1x would be one the bottom.

so t1y=1/2mg/sin70

that is as far as i could get with this problem. see, i really did try to do it. i just can't finish it. please, PLEASE help me. i really am trying!

2007-10-08 16:27:34 · 1 answers · asked by Elizabeth 3

I have a lab report in which I have drawn a velocity/time graph...there is only one question I don't understand:
What was the MAGNITUDE of the ball's acceleration in this lab?
Can anyone just explain to me what exactly magnitude is and how you solve or describe it!

THANK YOU!!

2007-10-08 16:12:58 · 3 answers · asked by Captain Oblivious 6

I was given a graph of force vs time. I was also given the mass of an object, kinetic and static friction coefficients. The question asks for the velocity of the object at certain times. i'm not sure how to incorporate the friction coefficients in. Can anyone help?

2007-10-08 15:57:03 · 1 answers · asked by stud muffin 2

a) has it already reached maximum height? Explain your answer
B)what is its kinetic energy at maximum height if the mass of the projectile is 2kg?

2007-10-08 15:53:25 · 1 answers · asked by Lim B 1

1. a ball is thrown into the air with an initial velocity of 35m/s. what is the maximum height the ball reached?

2. a plane experiences a constant acceleration. if the plane starts from rest and needs to reach a velocity of 50m/s to take off and the runway is only 500 meters long what is the acceleration needed for the plane to take off?

use the following equations:
-V=intial V+at
-X=initial X+initial V(t)+1/2at^2
-V^2=initial V^2+2a(X-initial X)

2007-10-08 15:47:30 · 1 answers · asked by anynomous 1