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Supplemental material

I recommend that you also study the other lessons in my extensive collection of online programming tutorials. You will find a consolidated index at www.DickBaldwin.com .

General background information

The gravitational constant

The gravitational constant, G, is a constant that is used in the calculation of the gravitational attraction between objects with mass. The value of G is approximately:

G = 6.67 * 10^(-11) *m^3*kg^(-1)*s^(-2), or

G = 6.67 * 10^(-11) N*(m/kg)^2

According to the law of universal gravitation, the attractive force (F) between two bodies is proportional to the product of their masses (m1 and m2), and inversely proportional to the square of the distance (r) between them:

F = G*m1*m2/r^2

Newton's law of gravitation

Newton's law of gravitation proposes that every small element of matter, m, attracts every other small element of matter, m' with a force that isproportional to the product of the masses and inversely proportional to the square of the distance between them, so that at the small element level,

F = G*m*m'/r^2

As a result, we tend to fall toward the earth unless we are supported by upward forces, such as the floor that we are standing on.

An important simplification

It would be very difficult to deal with the attraction of gravity if we were required to deal with every object (including the earth) in terms of the manysmall elements of mass that make up the object.

Newton simplified that process by proving mathematically that the earth regarded as a sphere attracts abody as if the whole mass of the earth were concentrated at its center.

Almost parallel forces

The attraction of the earth on the elements of our body produces forces on thoseelements that are almost parallel. Those forces lie along lines that all end at a point that is almost 4000 miles beneath the surface of the earth.

At that distance, each pair of force lines forms the sides of a triangle with extremely long sides, an extremely small angle, and an extremely narrow base. Asa practical matter, therefore, we can assume that those forces are parallel insofar as estimating the effectthat the sum of all of those elemental forces have on our bodies.

The center of gravity C.G.

It can be proved that:

The resultant of the weights of all the elements of a rigid body passes through a certain fixed point commonly called its center of gravity, C.G., regardlessof the orientation of that body relative to the earth.

For purposes of computations involving statics, the mass of a rigid body may be considered as if concentrated at it C.G., and its weight may be considered to centerat this same point.

(Recall that the weight of an object is the force required to cause the mass of that object to fall toward the center of the earth with an acceleration ofapproximately 32.2 ft/s^2 or 9.81 m/s^2.)

A plumb-bob or plummet

A plumb-bob or a plummet is a weight, usually with a pointed tip on the bottom, that is suspended from a string and used as a vertical reference line, or plumb-line.

Questions & Answers

Do somebody tell me a best nano engineering book for beginners?
s. Reply
what is fullerene does it is used to make bukky balls
Devang Reply
are you nano engineer ?
s.
what is the Synthesis, properties,and applications of carbon nano chemistry
Abhijith Reply
so some one know about replacing silicon atom with phosphorous in semiconductors device?
s. Reply
Yeah, it is a pain to say the least. You basically have to heat the substarte up to around 1000 degrees celcius then pass phosphene gas over top of it, which is explosive and toxic by the way, under very low pressure.
Harper
how to fabricate graphene ink ?
SUYASH Reply
for screen printed electrodes ?
SUYASH
What is lattice structure?
s. Reply
of graphene you mean?
Ebrahim
or in general
Ebrahim
in general
s.
Graphene has a hexagonal structure
tahir
On having this app for quite a bit time, Haven't realised there's a chat room in it.
Cied
what is biological synthesis of nanoparticles
Sanket Reply
what's the easiest and fastest way to the synthesize AgNP?
Damian Reply
China
Cied
types of nano material
abeetha Reply
I start with an easy one. carbon nanotubes woven into a long filament like a string
Porter
many many of nanotubes
Porter
what is the k.e before it land
Yasmin
what is the function of carbon nanotubes?
Cesar
I'm interested in nanotube
Uday
what is nanomaterials​ and their applications of sensors.
Ramkumar Reply
what is nano technology
Sravani Reply
what is system testing?
AMJAD
preparation of nanomaterial
Victor Reply
Yes, Nanotechnology has a very fast field of applications and their is always something new to do with it...
Himanshu Reply
good afternoon madam
AMJAD
what is system testing
AMJAD
what is the application of nanotechnology?
Stotaw
In this morden time nanotechnology used in many field . 1-Electronics-manufacturad IC ,RAM,MRAM,solar panel etc 2-Helth and Medical-Nanomedicine,Drug Dilivery for cancer treatment etc 3- Atomobile -MEMS, Coating on car etc. and may other field for details you can check at Google
Azam
anybody can imagine what will be happen after 100 years from now in nano tech world
Prasenjit
after 100 year this will be not nanotechnology maybe this technology name will be change . maybe aftet 100 year . we work on electron lable practically about its properties and behaviour by the different instruments
Azam
name doesn't matter , whatever it will be change... I'm taking about effect on circumstances of the microscopic world
Prasenjit
how hard could it be to apply nanotechnology against viral infections such HIV or Ebola?
Damian
silver nanoparticles could handle the job?
Damian
not now but maybe in future only AgNP maybe any other nanomaterials
Azam
Hello
Uday
I'm interested in Nanotube
Uday
this technology will not going on for the long time , so I'm thinking about femtotechnology 10^-15
Prasenjit
can nanotechnology change the direction of the face of the world
Prasenjit Reply
At high concentrations (>0.01 M), the relation between absorptivity coefficient and absorbance is no longer linear. This is due to the electrostatic interactions between the quantum dots in close proximity. If the concentration of the solution is high, another effect that is seen is the scattering of light from the large number of quantum dots. This assumption only works at low concentrations of the analyte. Presence of stray light.
Ali Reply
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
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Source:  OpenStax, Accessible physics concepts for blind students. OpenStax CNX. Oct 02, 2015 Download for free at https://legacy.cnx.org/content/col11294/1.36
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