Physics - October 2007

2007-10-20 15:37:31 · 8 answers · asked by Jade 3

Lightning an unlimited source of energy!!! Are we missing out on something?

2007-10-20 15:32:49 · 3 answers · asked by well dressed 1

The shape of the surface of water in a bucket is determined by the condition that the potential energy per unit mass, as determined in the frame in which the water is at rest, is constant at all places on the surface. Assume that the bucket is into rotation at an angular speed w about its vertical central axis and that the water rotates with the bucket. Write a formula that gives the shape of the water surface. (Hint provided by the book: Note that the normal force of the liquid must account for the centripetal acceleration).

2007-10-20 15:26:25 · 4 answers · asked by Anonymous

which has greater density 5 kg of lead or 10 kg of aluminum

2007-10-20 15:05:52 · 4 answers · asked by Anonymous

A 0.148 kg glider is moving to the right on a frictionless, horizontal air track with a speed of 0.900 m/s. It has a head-on collision with a 0.291 kg glider that is moving to the left with a speed of 2.16 m/s. Suppose the collision is elastic.

Find the magnitude of the final velocity of the 0.148 kg glider.

Find the direction of the final velocity of the 0.148kg glider. Left or right?

Find the magnitude of the final velocity of the 0.291 kg glider.

Find the direction of the final velocity of the 0.291kg glider. Left or right?

Thanks for your help!

2007-10-20 15:00:24 · 1 answers · asked by Frostie K 1

A metal sphere of radius R, carrying charge q, is surrounded by a thick concentric metal shell (inner radius a, outer radius b). The shell carries no net charge.

(A) Find the surface charge density R, at a, and at b.

(B) Find the potential at the center, using infinity as the reference point.

(C) Now the outer surface is touched to a grounding wire, which lowers its potential to zero (same as infinity). How do your answers (A) and (B) change?

2007-10-20 14:52:45 · 2 answers · asked by Nate-dawg 2

An archer shoots an arrow with a velocity of 51.5 m/s at an angle of 54.5° with the horizontal. An assistant standing on the level ground 150 m downrange from the launch point throws an apple straight up with the minimum initial speed necessary to meet the path of the arrow.
(a) What is the initial speed of the apple?
(b) At what time after the arrow launch should the apple be thrown so that the arrow hits the apple?

okay i got the first part of the question which equals 41.39 m/s. i cant solve part b. please help. thanks in advance.

2007-10-20 14:47:50 · 1 answers · asked by Quang P 2

This is a problem of mine for physics:

A car travels due east with a speed of 50.0 km/h. Rain is falling vertically with respect to the Earth. The traces of the rain on the side windows of the car make an angle of 50.0° with the vertical. Find the velocity of the rain with respect to each of the following.

a) The car(in m/s)
b) The Earth (in m/s)

I've been attempting these for a while. The only solution I could come up with for A is Tan50=x/13.9. I got the answer then converted from km/h to m/s to get 16.56. The computer is telling me this is wrong. I have no idea what to do next.

Any help or guidance would be great on both! Thanks!

2007-10-20 14:47:46 · 1 answers · asked by countrygurl587 3

All right, so I've been reading up on this Large Hadron Collider deal, and I'm not so sure I like the implications. Apparently, the scientists CONDUCTING the experiment aren't even sure what the thing does. When it is finally switched on, which I've heard will be anywhere from November 26, 2007 to May 2008, it will either, prove the big bang theory, by producing in layman's terms a little universe all it's own out of nothing, OR, it could create a black hole, or dimensional rift. Does anyone else think that this is a particularly BAD idea? Anyway, just something going through my head. You can look up the info on Wiki if you're unaware of this subject.

2007-10-20 14:44:05 · 6 answers · asked by temple_bishop 1

2007-10-20 14:20:23 · 5 answers · asked by blueridgemotors 6

2007-10-20 13:43:22 · 10 answers · asked by Anonymous

2007-10-20 13:33:25 · 3 answers · asked by Danny 1

a. If you press a book flat against a vertical wall with your hand, in what direction is the friction exerted by the wall on the book?

b. A crate is shitting in the center of a flatbed truck. As the truck accelerates to the east, the create moves with it, not sliding on the bed of the truck. In what direction is the friction force exerted by the bed of the truck on the crate?

Please also explain why. Thank you.

2007-10-20 13:32:29 · 7 answers · asked by Anonymous

A 450 kg mass is accelerated at 2.5 m/s^2.

a. What is the net force causing this acceleration?
b. How much distances will it cover after 3.5s

Please show me how to do this problem.

2007-10-20 13:28:29 · 3 answers · asked by Anonymous

009 (part 1 of 1) 10 points
A person of mass 77.9 kg escapes from a burn-
ing building by jumping from a window situ-
ated 23.7 m above a catching net.
The acceleration of gravity is 9:8 m/s2 :
If air resistance exerts a force of 76.7 N on
him as he falls, determine his speed just before
he hits the net. Answer in units of m/
s.

2007-10-20 13:23:28 · 3 answers · asked by dojorno5 2

2007-10-20 13:23:24 · 1 answers · asked by Sergio P 2

2007-10-20 13:10:54 · 2 answers · asked by Lostwithchem 1

V= Volt
I= current or amp
R= resistance or ohm


Your iPod’s battery produces 3.7v and the iPod circuit draws 0.1Amp from the battery. Check True or False (T/F) for the statements on the answer sheet (page 4 of this homework) for this problem.


(3) __F_ From Ohm’s law V=IR, there must be a 37Ohm resistor in your iPod.

By V=IR 3.7 V/.1 Amp = 370 R

___T_ Your iPod consumes 0.37W power.

P= VI .1 amp * 3.7 volt = .37 W

__T__If a 37Ohm resistor is connected to the iPod battery, it will consume the same power as your iPod.

V=IR V = .1 amp * .37 ohm = 3.7v’
P=VI 3.7 volt * .1 amp = .37 W


____You can store and play your favorite music on a 37 Ohm resistor.

WTF? FALSE?

____When you turn off the iPod, the battery voltage drop to zero.

TRUE?

____When you turn off the iPod, the current drawn from the battery drop to zero

TRUE?



Can you check my work for first 3 parts? Last parts I'm stuck. help?

Thanks for looking

2007-10-20 13:07:11 · 1 answers · asked by Ali G 1

While studing for a mechanics test, I created a problem that no one I knew including my professor could solve. I eventually solved it, and would like to see who else can.

You have a massless inclined plane whose angle is Theta. There is no friction or gravity anywhere in the problem. There is a block of mass M on the incline. You apply a force to the vertical part of the incline of F. The incline is attached to a rail so that it can only move left and right, so no up or down movement, and no rotation.

Remember no friction of gravity, massless inclined, M mass block, force F applied parallel to the base of the block to push it along the frictional rail.

What is the acceleration of the inclined Plane at any angle where theta is between 0 and 90 not inclusive. (at 90 they act as one piece, so its easy, and at 0 a force cant be applied at all!)

Good Luck!

2007-10-20 13:04:18 · 3 answers · asked by carrotstien 2

The resistance of a resistor is 9.1 Ohms and the resistance of a coil is 4.6 Ohms
(Both of these values were measured with an ohmmeter.)
What is the resistance of the circuit when driven at its resonant frequency?
__________________Ohms.
(Write N/A if there is not enough information to answer.)
Use Three Sig figs.

PLEASE HELP ME AND EXPLAIN, I'M CONFUSED ABOUT THIS, THANKS

2007-10-20 13:01:02 · 5 answers · asked by Anonymous

I know the electromagnetic spectrum goes from long to short wavelengths, starting with radio and ending in gamma waves. What is beyond these two 'end' waves. Is there an upper or lower limit to the EM spectrum?

Do Radio and Gamma waves have the widest range of frequencies? And if so, do they have the widest range of attributes?

2007-10-20 12:21:19 · 4 answers · asked by jos c 1

A 21g ball is fastened to one end of a string 68cm long and the other end is fixed to a point on a ceiling that makes an angle of 28 degrees with the vertical. This angle remains constant as the ball rotates in a horizontal circle. The angle theta would remain constant only for a particular speed of the ball in a circular path. The accleration og gravity is 9.8m/s2. FInd this speed. Answer in m/s

2007-10-20 11:28:11 · 1 answers · asked by akanthasy 1

A 21g ball is fastened to one end of a string 68cm long and the other end is fixed to a point on a ceiling that makes an angle of 28 degrees with the vertical. This angle remains constant as the ball rotates in a horizontal circle. The angle theta would remain constant only for a particular speed of the ball in a circular path. The accleration og gravity is 9.8m/s2. FInd this speed. Answer in m/s

2007-10-20 11:23:28 · 4 answers · asked by akanthasy 1

The pilot of an aircraft wishes to fly due west in a 50.0km/h wind blowing toward the south. The speed of the aircraft in the absence of wind is 305 km/h.
a) In what direction should the aircraft head?
b) What is the speed of the aircraft relative to the ground?

2007-10-20 09:18:01 · 1 answers · asked by brainless storm 1

well i guess its yes but if no one is there to hear it the sound wave would have never existed in time therefore making no sound??

2007-10-20 08:00:44 · 7 answers · asked by pokefreak 2

a librarian does 8J of work to stack 5 identical books on top of each other. if each book has a thickness of 4 cm, wat is the mass of the book?

Answer: 2 kg

plz help and show steps

thx

2007-10-20 07:40:37 · 2 answers · asked by Anonymous

Alright, here is the question. I'll tell you how far I've gotten trying to figure it out.

"A rifle with a weight of 40 N fires a 5.0 g bullet with a speed of 230 m/s.
(a) Find the recoil speed of the rifle.
(b) If a 600 N man holds the rifle firmly against his shoulder, find the recoil speed of the man and rifle."

The formula I've been attempting to use for recoil velocity of the rifle is m1v1(i) + m2v2(i) = m1v1(f) + m2v2(f)

Wouldn't the entire left side be equal to zero, as both the initial velocity of the rifle and the bullet are zero?

On the right side, I've plugged in m1 = 40N, v1 = ?, m2 = .005 kg (mass of bullet conv. to kg), and v2 = 230 m/s. Solving for v1(f) where the left side has a value of 0, I get the answer -.02875 m/s (recoil velocity of the rifle). This is coming back wrong. What am I missing? Am I even using the right formula? Thanks!

2007-10-20 07:32:28 · 3 answers · asked by justme 4

1) A vector 5 cm long at 45 degrees. Find horizontal and vertical components graphically. Express as vectors (+/- for direction and X or Y with length and units).
2) What is resultant of vector 30 m/s East and 40 m/s south? (remember angle and magnitude)
How could Pythagorean theorem apply to number 2?

How do I do this?

2007-10-20 06:58:06 · 3 answers · asked by rockchick 2

geometry help plz!!!!

2007-10-20 06:53:00 · 1 answers · asked by Nat 1

Objects with masses of 120 kg and a 420 kg are separated by 0.310 m.

(a) Find the net gravitational force exerted by these objects on a 50.0 kg object placed midway between them.
4.1642E-5 N

(b) At what position (other than infinitely remote ones) can the 50.0 kg object be placed so as to experience a net force of zero?




[That's not the correct answer, hmata3. stfu.]

2007-10-20 06:36:35 · 2 answers · asked by Burton 1