IIT JEE , AIEEE Forum - Physics , General

KraniuM

Is there any logical meaning of the phrase "The weight of the earth" knowin dat weight is d force by which the earth pulls objects towards its centre,.....i.e. F=mg,...

karthik_abiram

do u mean mass of the earth?

mass of the earth is 5.98 * 10²⁴

but dunno abt weight of the earth!

KraniuM

hey mass is constant dats kool, but weight depends on gravity, so wts d meaning of Wight of the Earth??

karthik_abiram

can u plz tell me where u came across the term?

so that i too can get some idea.........

KraniuM

vell, like evry object has sum weight as vell as mass,.......som dus earth has any weight?? dats wt struck me, dats hw i came across it....

karthik_abiram

ok,lets see what the experts say.....

karthik_abiram

it seems that they are one and the same..........but i m sure that this is wrong!

see:-

"""""""""'Earth weighs 5,972,000,000, 000,000,000, 000 tons""""""""'

source:

http://www.4to40.com/omg/index.asp?id=2129&category=earth

but i m sure this is wrong........as weight=mg

wat do u think abt this ?

edison

Mass of earth is =Me = 5.98 x 10²⁴ kg

Due to this mass there is a gravitational force of attraction between earth and objects on the earth.

So, acceleration due to gravity on earth's surface is defined as g = GMe / R²

Where, R is radius of earth ~ 6400km = 6.4 x 10⁶ m

or, g = GMe / R² = 9.8 m/s²

Now keeping the same fact in mind if we try to asscociate weight of earth it meas

Weight of earth = mass of earth x g'

where g' is accleleration on earth due to bodies present in its vicinity as well due to other celestial bodies like sun etc.

But the bodies on earth are having masses too small that contributes negligibly towards g'

Similarly if we try to find out the contribution from SUN towards g' then

we see that g' = G (mass of sun)/ (distance between sun and earth)²

= G Ms / R_es²

Here R_es = distance b/w earth and sun = 1.52 x 10¹¹ (Aphelion)

also R_es = 1.47 x 10¹¹ ( At the time of Perihelion)

Thus if we take R_es = distance b/w earth and sun = 1.52 x 10¹¹

G = 6.64 x 10^-11

Ms = 1.98 x 10³⁰ kg

then we find that g' ~ 10^-9

Which is far less and negligible.

Weight of earth due to sun = Me x g' ~ 12 x 10¹⁵N

thus in this way the weight of earth can be associated and corelated due to the prescence of celestial or other heavy bodies in its vicinity.

Though there is no specific and standard idea to estimate weight of the earth due to ambiguity involved in the preoblem as evident from above analytical but crude example.

vinod

perrrfeectttttt

KraniuM

tnx man perfect answer

avinash.sharma

Edison has very nicely explained the concept of weight of Earth.

Ask & Discuss Questions with Community & Experts