Physics - June 2007

2007-06-04 14:50:54 · 5 answers · asked by robertotk 2

2007-06-04 14:50:20 · 4 answers · asked by Nezar 1

I have a physics final tomorrow and I can't figure out this problem.

You want to push a 75N crate across the floor. What force is required to move the crate at a constant velocity if the coefficient of friction is .320?

2007-06-04 14:44:47 · 1 answers · asked by Anonymous

Hi,

A distant quasar is found to be moving away from the earth at 0.5c. A galaxy closer to the earth and along the same line of sight is moving away from us at 0.4c. What is the recessional speed of the quasar as measured by astronomers in the other galaxy?

It should be less than 0.5c right? I am thinking about using Lorentz transformation for velocity:

u' = (u - v) / (1 - uv/c^2). My question with that is why are there 3 velocites: u', u, and v? Those are all velocities, right?


Thanks!

2007-06-04 14:36:54 · 4 answers · asked by Anonymous

2007-06-04 14:35:46 · 3 answers · asked by delvic56 1

This is really more of a math problem, but I can't figure out what I'm doing wrong..."The standard kilogram is a platiunum-irridium cylinder 39.0 mm in height and 39.0 mm in dm. What is the density of the materia?"

Assuming that density is equal to mass/volume, I first calculated the volume of the cylinder, using the formula Volume=r^2(height)pi(19.5^2)(39)(pi)=46589 mm^3. I then divided 1kg by this number.

My answer was 2.15x10^-5 kg/m^3. However, the book says my answer should be 2.15 x 10^4 kg/m^3, which is obviously a big difference. Any help would be greatly appreciated!!

2007-06-04 14:30:44 · 8 answers · asked by Anonymous

2007-06-04 14:10:34 · 10 answers · asked by Life goes on... 6

Is the method for finding the spring constant for a pull spring the same for a compression spring?

2007-06-04 11:59:54 · 2 answers · asked by fye 1

Like dogs see black and white and for some animals the colors are brighter coloured, like infared

2007-06-04 11:56:24 · 12 answers · asked by Anonymous

Please state answer and explain:

What is the recoil velocity of a 0.75 kg gun when the bullet it fires has a mass of 10 g and a velocity of 500 m/sec?

A. 6666.7 m/sec
B. 37.5 m/sec
C. 37500 m/sec
D. 6.7 m/sec

Thank-you, you are a genius.....(IF YOU ARE CORRECT!)

2007-06-04 11:54:54 · 7 answers · asked by doubleK 2

A higher than
B.lower than
C.the same as
D.both a and b

2007-06-04 11:51:17 · 2 answers · asked by lady_hustla_09 1

A.are compresssional waves
B.are transverse waves
C.must have a medium
D.are generated by static electricity

2007-06-04 11:47:10 · 2 answers · asked by lady_hustla_09 1

I heard recently that when a bullitt from a gun hits a victim it wold not actually make the victim fly back/forward. instead the person would just fall in which ever direction it was going with no extra force. Meaning this was solely made up to look good in films etc. Not sure what this effect is called. its not recoil but i can't think of a suitable word. i've never seen enough people getting shot to tet the experiment...

2007-06-04 11:41:45 · 5 answers · asked by kenily 2

a. electron
b. proton
c. neutron
d. nucleus

2007-06-04 11:38:56 · 7 answers · asked by Anonymous

Hello,

If you can't describe it then you don't know what it is... "so what is space?"

kindest regards,
rlj

2007-06-04 11:26:45 · 8 answers · asked by reverendlovejoy75 3

Remember m = mass
and E being energy which is light or photons

2007-06-04 11:24:17 · 12 answers · asked by AndreL 2

2007-06-04 11:24:17 · 12 answers · asked by Anonymous

that you hear increase, decrease or stay the same. how about the wavelength reaching your ear? how about the speed of sound in the air between you and the locomotive?

2007-06-04 11:23:49 · 3 answers · asked by Anonymous

Is it possible to shrink a quarter to the size of a dime with magnetism? I saw an offering on ebay for just such a coin and was wondering if it is a scam?

2007-06-04 11:05:29 · 6 answers · asked by charley 2

scw287

scw287 is Online:
Posts: 20
Projectile Velocity
A rocket is fired at a speed of 75.0 m/s from ground level, at an angle of 66.4° above the horizontal. The rocket is fired toward an 11.0 m high wall, which is located 20.0 m away. The rocket attains its launch speed in a negligibly short period of time, after which its engines shut down and the rocket coasts. By how much does the rocket clear the top of the wall?

I know you use V_x = 75.0 m/s * cos(66.4 degrees) =30.026

not sure what you do next

2007-06-04 10:19:20 · 3 answers · asked by wildcherrychica1 2

2007-06-04 09:32:06 · 1 answers · asked by resliance 1

space like it wants too? Everything wants to return to an equalibrium so why doesn't the forces in space like gravity, vacuum pressure and all the other forces in nature it seems like everything would end up going to an evened out state

2007-06-04 09:17:57 · 6 answers · asked by hindsight2020612 2

2007-06-04 09:11:18 · 4 answers · asked by Anonymous

If you made a vaccum chamber would it make the small paticles floating around in the air to fall to the ground becaus of no wind resistence; and how much pressure would you need for it to be a vaccum. Would putting a fish tank air pump in the vaccum chamber with the hose attached to a one way valve pumping the air out be powerfull enough to creat a vaccum.

2007-06-04 08:37:24 · 6 answers · asked by Anonymous

If you made a vaccum chamber would it make the small paticles floating around in the air to fall to the ground becaus of no wind resistence; and how much pressure would you need for it to be a vaccum. Would putting a fish tank air pump in the vaccum chamber with the hose attached to a one way valve pumping the air out be powerfull enough to creat a vaccum.

2007-06-04 08:35:46 · 2 answers · asked by Anonymous

A man entered a cave and walked 100m north. He then made a sharp turn 150 deg to the west and walked 87m straight ahead. How far is the man from where he entered the cave?

2007-06-04 08:17:14 · 2 answers · asked by madaboutpizza 1

If we have 6 liter basket filled with 10kg of sand of density
2kg/liter, and we pour 1 liter of water and the basket is full.

The sand will lose 5kg of weight due to buoyancy,
and total weight of the basket should become
(10kg - 5kg) + 1kg of water = 6 kg. How come?

2007-06-04 07:50:36 · 7 answers · asked by Alexander 6

Lets say I dropped out the the sky and a helicopter was on the ground and its rotors were going and I fell right into them. I want to understant the full details of what would happen.

2007-06-04 07:12:46 · 11 answers · asked by Noah F 1

2007-06-04 07:09:49 · 8 answers · asked by Anonymous

They are made of metal, so why are they not magnetic?

2007-06-04 06:49:50 · 9 answers · asked by Anonymous