Ok...I have one damn problem left, and I cant get it for the life of me.

Use the data of Table 7.3 to find the point between Earth and the Sun at which an object can be placed so that the net gravitational force exerted by Earth and Sun on this object is zero. (the distance between earth and sun is 1.496x10^11 fyi)...


help please??

3/29/2006 5:13:04 PM

what's in Table 7.3?

3/29/2006 5:39:19 PM

the distances of different planets from the sun, masses and radii......so...i suppose if you need those for earth/the sun i could give those....

earth: mass (5.98x10^24kg) radius (6.38x10^6) period (3.156x10^7)
sun: mass (1.991x10^30) radius (6.96x10^8)

3/29/2006 5:45:46 PM

there should be a formula (in the book) that equates gravitational force to distance, radius, mass, etc.

the forces are equal

make one distance "X", and the other "1.496x10^11 - X"

solve for X

3/29/2006 9:37:24 PM

Quote :

"Lagrangian point From Wikipedia, the free encyclopedia Jump to: navigation, search The Lagrangian points (IPA: [l?.'gr?n.d?i.?n] or [la.'grã.?i.?n]; also Lagrange point, L-point, or libration point), are the five positions in interplanetary space where a small object affected only by gravity can theoretically be stationary relative to two larger objects (such as a satellite with respect to the Earth and Moon). They are analogous to geosynchronous orbits in that they allow an object to be in a "fixed" position in space rather than an orbit in which its relative position changes continuously. A more precise but technical definition is that the Lagrangian points are the stationary solutions of the circular restricted three-body problem. For example, given two massive bodies in circular orbits around their common center of mass, there are five positions in space where a third body, of comparatively negligible mass, could be placed which would then maintain its position relative to the two massive bodies. As seen in a frame of reference which rotates with the same period as the two co-orbiting bodies, the gravitational fields of two massive bodies combined with the centrifugal force are in balance at the Lagrangian points, allowing the third body to be stationary with respect to the first two bodies. "

Quote :

"Earth-Sun Lagrangian points [edit] L1 L1 is the Lagrangian point located approximately 1,500,000 km towards the Sun away from the Earth. [edit] Past probes International Cometary Explorer, formerly the International Sun-Earth Explorer 3 (ISEE-3), knocked out of L1 in 1983 for a comet rendezvous mission. Currently in solar orbit, it may be captured in 2014 when it next approaches Earth. Genesis, which returned to Earth in September 2004 after collecting solar wind particles for three years. The sample return capsule crash-landed in Tooele County, Utah, when its parachute failed, making its planned airplane-grab recovery impossible. Usable samples were recovered from the capsule anyway, making the mission a partial success. WIND, a NASA spacecraft, was launched in November of 1994 in order to study solar wind. The spacecraft's original mission was to orbit the Sun at the L1 Lagrangian point, but this was changed when the SOHO spacecraft was sent to the same location. [edit] Present probes The Solar and Heliospheric Observatory (SOHO) The Advanced Composition Explorer (ACE) [edit] Planned probes LISA Pathfinder [edit] Cancelled probes The Triana satellite [edit] L2 L2 is the Lagrangian point located approximately 1,500,000 km away from the Earth in the direction opposite the Sun. [edit] Present probes Wilkinson Microwave Anisotropy Probe (WMAP) [edit] Planned probes The joint NASA, ESA and CSA James Webb Space Telescope (JWST), formerly known as the Next Generation Space Telescope (NGST) The ESA Herschel Space Observatory The ESA Planck Surveyor The ESA Gaia probe The NASA Terrestrial Planet Finder mission (may be placed in an Earth-trailing orbit instead) The ESA Darwin mission [edit] Cancelled probes The ESA Eddington space telescope [edit] L3 L3 is the Lagrangian point located on the side of the Sun opposite the Earth, slightly outside the Earth's orbit. There are no known objects in this orbital location. [edit] L4 L4 is the Lagrangian point located in the Earth's orbit 60° ahead of the Earth. Dust clouds [1] [edit] L5 L5 is the Lagrangian point located in the Earth's orbit 60° behind the Earth. Dust clouds "

Heres what I found on wiki... don't know if it will help at all.

3/29/2006 9:46:16 PM

And remember that you're considering these objects as particles, so the force will act from the center of the object.

3/29/2006 9:49:26 PM

Quote :

"there should be a formula (in the book) that equates gravitational force to distance, radius, mass, etc. the forces are equal make one distance "X", and the other "1.496x10^11 - X" solve for X"

and use F=GmM/r^2 for the forces, one has r=X the other r=.496x10^11 - X. And M should either be the mass of sun (Mo)or the mass of the earth (Me)
This gives

GmMo*m/X^2=GMe*m/(.496x10^11 - X)^2

Now cancel m and G and invert both sides,

X^2 / Mo= (.496x10^11 - X)^2 / Me

Behold, the above is merely a quadratic equation. Just take the squareroot and remember the plus/minus. Or alternatively foil out the squared term and collect terms so you can apply the quadratic formula.

3/29/2006 10:25:14 PM

I still have this one left if anyone can help me.. Biochem has fried my brain

An air puck of mass 0.23 kg is tied to a string and allowed to revolve in a circle of radius 1.0 m on a frictionless horizontal table. The other end of the string passes through a hole in the center of the table, and a mass of 1.2 kg is tied to it (Fig. P7.25). The suspended mass remains in equilibrium while the puck on the tabletop revolves.

What is the tension in the string?

(b) What is the force causing the centripetal acceleration on the puck?
N
(c) What is the speed of the puck?
m/s

3/30/2006 12:06:25 PM

part b is the same answer as a
gravity * mass of the hanging weight

3/30/2006 12:20:40 PM

Thanks.. I knew it had to be simple and I just couldn't see it for trying!

3/30/2006 1:30:42 PM

hey
mass of the sun is in the book, right?

i'm at work and don't have my book with
can someone post that for me?

3/30/2006 1:47:43 PM

Quote :

"mass of the sun is in the book, right?"

look up to my 2nd post. it's in there.....if you figure it out, let me know...cuz ive yet to get it. (i swear its right but webassign begs to differ)

3/30/2006 4:35:08 PM

Quote :

"and use F=GmM/r^2 for the forces"

that's the one...

3/30/2006 4:54:39 PM