Physics - February 2007

Okay, I thought I understood this but my homework site is telling me otherwise. What I did was add the total votage and came out with 40.12. I'm not sure if that is what I'm suppose to do or not for part (a).

Three resistors are connected in series across a battery. The value of each resistance and its maximum power rating are as follows: 5.0 and 20.5 W, 31.5 and 10.0 W, and 15.0 and 10.0 W.

(a) What is the greatest voltage that the battery can have without one of the resistors burning up?
V
(b) How much power does the battery deliver to the circuit in (a)?
W

If I know (a) then I should be able to do (b) by myself

2007-02-02 08:40:12 · 4 answers · asked by Confused 1

Stone falls into a deep well, you hear it hit 3.2 seconds later. Thats the time it took for the stone to fall + the time it took for sound to travel back up the well to you. Sound is traveling at 343m/s how deep is the well?


There werent any other givens and I cant think of a way to approach the problem without knowing more, any ideas?

2007-02-02 08:18:42 · 4 answers · asked by lostcausechalupa 1

solve for the system of equations:
If v=vc +at AND
delta x= (_v + vc)t
2
show that delta x= vct=atsquared over 2
hint you need to eliminate the v
can someone please help me with this question.
Thanks

2007-02-02 08:04:28 · 1 answers · asked by Anonymous

I need to ask that some 'thing' must have changed into energy!! what is that thing ? or how this energy came into existence ..Though we say that energy can neither be created nor be destroyed..that means its content is infinty because a slight change in its contents is negligible.

2007-02-02 08:02:07 · 5 answers · asked by pp 1

if it is possible,then we should doubt about einstein teoris?is it true tht ufos(if they exist)prove tht einstein was wrong about hes teoris?
imagine E^2-c^2P^2=m^2c^4
and p is the distance...if m2>0,then E>cp,we use it for attoms,and microscopic materials
M2=0,so vc ?r tachyons exist?

2007-02-02 07:50:52 · 2 answers · asked by Anonymous

A positron (a particle with a charge of +e and a mass equal to that of an electron) that is accelerated from rest between two points at a fixed potential difference acquires a speed of 9.0 x 10^7 m/s.
What speed is achieved by a proton accelerated from rest between the same two points? (Disregard relativistic effects.) Answer in m/s.

2007-02-02 07:47:36 · 1 answers · asked by Derrick Z 1

This is kind of a weird question but yeah.

2007-02-02 07:47:27 · 11 answers · asked by El Hombre 2

Can anyone help?

A 8.5 kg mass is given an initial velocity of 13 m/s up an incline that makes an angle of 37° with the horizontal. When its displacement is 8 m, its upward velocity has diminished to 5.2 m/s.
(a) Find the coefficient of kinetic friction between the mass and the plane.
(b) Find the displacement of the mass from its starting point at the time when it momentarily comes to rest.
(c) Find the speed of the block when it again reaches its initial position.

2007-02-02 07:44:08 · 1 answers · asked by Froggiesmiles 3

hiya people say its not the current that kills you but the amps......so if the voltage is 240v and the watts is 20 w please could someone tell me the ampage is and if this is enogh to kill you,

Thanks

Nasser

2007-02-02 07:33:51 · 8 answers · asked by nasserc267 1

A glider of mass 0.250 kg moves on a horizontal frictionless airtrack. It is permanently attached to one end of a massless horizontal spring, which has a force constant of 13.0 N/m both for extension and for compression. The other end of the spring is fixed. The glider is moved to compress the spring by 0.180 m and then released from rest.

(a) Calculate the speed of the glider at the point where it has moved 0.180 m from its starting point, so that the spring is momentarily exerting no force.
(b) Calculate the speed of the glider at the point where it has moved 0.250 m from its starting point.

2007-02-02 07:31:49 · 1 answers · asked by Victoroza 1

2007-02-02 06:56:49 · 2 answers · asked by rdwesley@swbell.net 1

The charge on a capacitor increases by 15 µC when the voltage across it increases from 81 V to 121 V. What is the capacitance of the capacitor?
The answer shoul be Farad (F)

2007-02-02 06:33:43 · 3 answers · asked by ZG786 1

i dont understand:
draw dot diagrams for one Li and one Cl atom.
write the symbols for these ions that show their overall charge.
write the formula for the compound formed.

if you know the answer, please explain it so, i can do the other problems as well

2007-02-02 06:32:06 · 2 answers · asked by globalpinaygirl 2

When would a small car have the same momentum as a large truck?
(a) when the velocity of the truck is much greater than the velocity of the car?
(b) when the velocity of the car and truck are wequal
(c) never
(d) when the velocity of the car is much greater than the velocity of the truck
(e) none of the above

2007-02-02 06:14:50 · 4 answers · asked by Hey ;) 3

If black color doesnt reflect any light and white is combination of all colors (someone even told me these colors dont theoretically exist) than what is grey color and how it is possible we can see it? If it reflected only half of the spectrum than white+black should create color that is in the middle of a spectrum... can you explain this?

2007-02-02 06:14:14 · 7 answers · asked by eldridan 3

(a) What is the kenetic energy of a 2670-kg car that is traveling at 97.0 km/h?____kj
(b) How much work was fone to give the car this kenetic energy?____kj
(c) How much work was done to stop the car?_____kj

2007-02-02 06:11:41 · 2 answers · asked by Hey ;) 3

There have been some Cosmologists/Astrophysicists who think that the Speed of Light may not have been constant, i.e. it may have had a different value in the early universe. If this proved to be true, since the Speed of Light is the "constant" C in E=Mc2, does this mean matter and energy would have had a different equivalence rate in an earlier era in the universe's history?

2007-02-02 06:07:42 · 8 answers · asked by chris_writerinsf 2

2007-02-02 06:06:30 · 17 answers · asked by KIERAN W 1

How much work was is needed to stop a 2710-kg car that is moving strait down the highway at 71.0 km/h?
_____*10____j

2007-02-02 06:01:42 · 1 answers · asked by Hey ;) 3

please answer it pointwise and giive the answer scientifically reffering some enginneering books

2007-02-02 05:36:10 · 1 answers · asked by ABHISHEK 1

I am not sure if it is possible to do, but I was wondering if it is. A ball at rest begins rolling down a ramp at uniform acceleration. In the second 5 seconds (time 5

2007-02-02 05:24:07 · 2 answers · asked by Anonymous

2007-02-02 05:14:42 · 3 answers · asked by Anonymous

Not a huge one or anything either

2007-02-02 04:56:48 · 5 answers · asked by Anonymous

2007-02-02 04:21:26 · 14 answers · asked by Anonymous

2007-02-02 04:15:20 · 1 answers · asked by Kristada 2

An explorer is caught in a whiteout (in which the snowfall is so thick that the ground cannot be distinguished from the sky) while
returning to base camp. He was supposed to travel due north for 5.4 km, but when the snow clears, he discovers that he actually traveled 7.8 km at 53° north of due east.

(a) How far must he now travel to reach base camp?
km

(b) In what direction must he travel?
° (counterclockwise from due east)

2007-02-02 03:37:53 · 3 answers · asked by mehran_kimi 2

I've been trying to teach myself relativity, but I'm stuck on a conceptual question involving Ehrenfest's Paradox. If you don't remember...the paradox involves a spinning disk. Presumably, the disk is Lorentz contracted along the direction of its motion but not along its radius. In other words, its circumference shrinks when it spins but its radius stays the same because its perpendicular to the disk's motion. Doesn't that mean that the ratio of the circumference of the disk to it's diameter will be greater than pi? How can the disk shrink while it's radius stays the same? How can that be? How is this paradox resolved? No comprendo Professor...que paso?

2007-02-02 03:37:21 · 3 answers · asked by Link 5

200 g of steam at 100 degrees C is added into the mixture. Find the final temperature of the mixture

Cs = 3764.4 J/kg C
Ci = 2140 J/kg C
Cw = 4186 J/kg C

2007-02-02 03:17:54 · 2 answers · asked by fatalmelody 2

2007-02-02 03:12:08 · 10 answers · asked by WELL SAID ERFMAN JACK 2

She occurs with the mechanics of the Land, interacting with the magnetism of the Sun opposes to the one of the Interstellar System. E you! Which its version?

2007-02-02 03:09:36 · 1 answers · asked by britotarcisio 6