Physics - September 2007

I can't seem to find any information on this in the book, nor do I feel like I really understand the concept. Any help would be greatly appreciated!!!

1. Block m1 has a mass of 4 kg and m2 has a mass of 2 kg. The coefficient of kinetic friction between m2 and the horizontal plane is 0.5. The incline plane is frictionless. The angle of the incline plane is 30 degrees.
a) Calculate the tension in the cord.
b) Calculate the acceleration of the blocks.

2007-09-27 05:54:29 · 4 answers · asked by soliel021 3

A sign is suspended from two chains AE and BF. Knowing that the tension in BF is 200 N, determine (a) the moment about A of the force exterted by chain B, (b) the smallest force applied at C which creates the same moment about A.

Diagram:
http://i236.photobucket.com/albums/ff35/bugmenot_07/6.jpg

2007-09-27 05:24:09 · 1 answers · asked by Tyrese B 1

site for online dictionary with physics terms?(romanian-english,english romanian)

2007-09-27 05:07:40 · 4 answers · asked by Anonymous

2007-09-27 05:07:12 · 4 answers · asked by laurenhall2006 1

These questions are for fall arrest systems.
1. A 180LB man has a 10' rope tying him to a bolt in a wall. The man free falls for 10'. How much force (lbs) is applied to the bolt when he comes to a sudden stop?
2. Now, the last 3' of the 10' rope is set-up to decelerate the 180LB man. (Man free falls for 7' then decelerates for 3'). How much force (lbs) is applied to the bolt at 7' (point of deceleration) and at 10' (end of 3' deceleration)?

please post answers in Lbs.

2007-09-27 04:42:59 · 1 answers · asked by shaggz28 1

when we roll a piece of material,for instance, paper or plastic, it rolls back. What is the force or energy involved? Is there any scientific theory behind such phenomenon?

2007-09-27 04:30:31 · 2 answers · asked by howard c 1

a 72 degree room, which one will reach room temperature first? Why? This debate has occupied 20 minutes of mine and my co-workers time... please help us answer this so we can get back to work!

2007-09-27 04:22:11 · 9 answers · asked by Anonymous

Hollow iron sphere full of 1,000 liters of liquid sodium @400C. The iron sphere has an initial average temperature of 50C, and a total heat capacity of 10,000kJ/C. The sphere is submerged in 10,000 liters of water @25C. How much water will flash to steam in a room at a vacuum of 25" Hg?

http://s223.photobucket.com/albums/dd78/floodtl/?action=view¤t=LatentHeat.jpg

2007-09-27 04:18:04 · 3 answers · asked by Anonymous

Hey everyone someone please help. I asked my professor about this in class and he didnt listen to me just interupted so i still dont know. here it is
2 transparent materials having indexes of refraction 1.27 and 1.31 are placed in to contact. Is it possible for total internal reflection to occur at the boundry between the two materials? In either case, be specific about details or constrants.

Some one help all i know is it has something to do with n1 (v1)=n2(v2) or something like that.

2007-09-27 04:08:27 · 2 answers · asked by DP 3

What are some of the biggest problems of inventing a time machine, besides the obvious technological inability of humans so far.

2007-09-27 03:44:35 · 7 answers · asked by Antares 6

2007-09-27 03:15:58 · 4 answers · asked by ppstream 1

lol everyone's answers have been so helpful when i asked about physics yesterday i thought id throw one more out there

this one is pretty simple, i think.. its just that neither my textbook OR the notes from class show an example similar to this, so i dont really know where to start...

"a child slides down a slide with a 28 degree incline, and at the bottom her speed is precisely half of what it would have been if the slide had been frictionless. Calculate the coefficient of kinetic friction between the slide and the child."
i might need to use

force of friction = coefficient of kinetic friction x normal force

but idk an equation that relates with angles!

2007-09-27 02:29:25 · 5 answers · asked by Anonymous

2007-09-27 02:03:10 · 2 answers · asked by Jackie 4

2007-09-26 23:16:43 · 5 answers · asked by Vaibhav Khurana 1

after watching sunshine, the concept of moving close to the sun seems easy, so long as you can get a perfect enough mirror to reflect 100% of the light. would it take more than a perfect mirror, and if not, how could such a reflective object be made?

2007-09-26 21:59:16 · 3 answers · asked by Anonymous

A m = 1.9 kg wood box slides down a vertical wood wall while you push on it at a = 48° angle. What magnitude of force should you apply to cause the box to slide down at a constant speed?
N

2007-09-26 20:14:49 · 1 answers · asked by Jim E 1

we have a kind of room heater which is a combination of storage, radiant and convection. My question is - does it take the same amount of electricity to heat the ceramic core from cold to 10 degrees as it does to heat it from 10 to 20 degrees? I suppose I am asking whether the heating effort is in a straight line or a curve. I know there is a unit Kelvin or whatever which is supposed to be constant but does it vay depending on the material being heated and the temperature it has reached so far?

2007-09-26 20:01:29 · 2 answers · asked by XT rider 7

--->Amtrak's 20th century limited is en route from chicago to new york at 110 km/h when the engineer spots a cow on the track. The train brakes to a halt in 1.2 min, stopping just in front of the cow.

(a) what is the magnitude of the trains (constant) acceleration? (b) what is the direction of the acc?
(c) how far was the train from the cow when the engineer first applied the brakes

&

-->an objects is moving initially in the x direction at 4.5 m/s^2 when an acceleration is applied in the y direction for a period of 18 seconds. if the object moves equal distances in the x and y directions during this time, what is the magnitude of the acceleration?

2007-09-26 19:46:09 · 1 answers · asked by Tommy 2

I need to know k, if I had one I could figure it out, but I'm trying to figure it out before hand.

2007-09-26 19:05:26 · 1 answers · asked by badaerozepstones 3

Can anyone tell me the correct equation thats something like X= Xo + Vt + 1/2at^2 or something like that?

2007-09-26 18:25:54 · 3 answers · asked by Anonymous

I remember learning, once, an equation that related the index of refraction of a substance to the wavelength of the light entering. Index of refraction as a function of wavelength. I have a degree in physics, but I only have a vague memory of this. Please help.

2007-09-26 18:21:58 · 4 answers · asked by Michael S 2

as a traffic light turns green, a waiting car starts with a constant acceleration of 6.0m/s^2. At the instant the car begins to accelerate , a truck with a constant velocity of 21m/s passes in the next lne(hint/: set the two distance equations equal to each other)
plz ansdwer step by step and show the work then you will get 10 free pts thx
a. how far will the car travel before it overtakes the truck
b how fast will the car be traveling when it overatakes the truck?
2. a stone falls freely from rest for 8.0s.
a. calculate the stone's velocity after 8.0s
b what is the stones displacement during this time?
3. a student drops a rock from a bridge to the water 12.0m below with what speed does the rock strick the water?

thank you for solving th is hard question to me

2007-09-26 18:14:52 · 1 answers · asked by Anonymous

i need major help
an physist in my life right now would be great
PLEASE
see if you can answer this question-

i will be dropping an egg on my teachers head while on top of a tower thats 8.52 meters
my teacher will be on the bottom and walking towards the tower from 4 meters away
my teachers steps are 57.48 cm long and shell walk at a rate of 100 steps per minute
my teacher is 1.62 meters tall
ive already calculated that its going to take my teacher 4.175 seconds to reach the tower from her 4 meter away starting point
i need to find out at what time i should drop the egg so that it will land on my teachers head right when she reaches the end of the 4 meter point
PLEASE help
me
and if possible
tell me how u got the answer

2007-09-26 18:13:03 · 2 answers · asked by Anonymous

as a traffic light turns green, a waiting car starts with a constant acceleration of 6.0m/s^2. At the instant the car begins to accelerate , a truck with a constant velocity of 21m/s passes in the next lne(hint/: set the two distance equations equal to each other)
plz ansdwer step by step and show the work then you will get 10 free pts thx
a. how far will the car travel before it overtakes the truck
b how fast will the car be traveling when it overatakes the truck?
2. a stone falls freely from rest for 8.0s.
a. calculate the stone's velocity after 8.0s
b what is the stones displacement during this time?
3. a student drops a rock from a bridge to the water 12.0m below with what speed does the rock strick the water?

2007-09-26 18:12:56 · 2 answers · asked by Anonymous

WHY DOES ICE FLOAT ON WATER

2007-09-26 18:00:30 · 3 answers · asked by ? 3

If anyone can help me out, it'd be REALLY helpful!

thanks!

2007-09-26 16:29:13 · 3 answers · asked by gatorbabe09 2

I swear im not just fishing for answers lol i just need some help and my book is not doing the trick..

"what is the weight of a 76kg astronaut on (a)Earth, (b) on the moon (g = 1.7m/s2) and, (c) on mars (g= 3.7m/s2) and (d) in outer space traveling with constant velocity?"

i know that F=mg in this case, and i understand the difference between weight and mass.. I guess im just having trouble understanding... do i use 9.8m/s2 for g when im calculating for earth? cause then i get a really high (unrealistic) weight. and wouldnt weight and mass be the same on earth anyway? lol now im just thinking too much.. ANY help please :)

2007-09-26 16:01:50 · 6 answers · asked by Anonymous

A ball held by a string is coasting around in a large horizontal circle. The string is then pulled in so the ball coasts in a smaller circle. When it is coasting in the smaller circle its speed is:

a) greater
b) less
c) unchanged

Yes - I know it's not a difficult question but it allows for a great discussion of the mechanics involved and relates to the last question nicely.

2007-09-26 16:00:54 · 3 answers · asked by ? 6

A jet is launched from an aircraft with the aid of its own engines and catapult. The thrust of its engines is 3.76*10^5 N. In being launched from rest it moves through a distance of 69.6 m and has a kinetic energy of 5.72*10^7 J. What is the work done on the jet by the catapult?

2007-09-26 15:11:06 · 1 answers · asked by txsweetpea512 1

Astronauts use a centrifuge to simulate the acceleration of a rocket launch. The centrifuge takes 40.0 s to speed up from rest to its top speed of 1 rotation every 1.40 s. The astronaut is strapped into a seat 4.30 m from the axis. What is the astronaut's tangential acceleration during the first 40.0 s? How many g's of acceleration does the astronaut experience when the device is rotating at top speed? Each 9.80 m/s^2 of acceleration is 1 g.

2007-09-26 15:04:54 · 2 answers · asked by Anonymous