, GRAVITATION 1-11-1115
NEWTONS LAW OF UNIVERSAL GRAVITATION -
every paiicunim mass in the universe
attracts every other particle with a force which is
directly proportional to the product of their masses and
inversely proportional to the square of the distance between their centres .
^
F
F -
Force of attraction between two objects (N ) Fdr . .m2
^ ' m2
"
kg 2)
f- ✗
_
N m2
-
f- = 6min 2 G -
Universal gravitational constant [ 6,7×10 .
.
r r 2
v2
mi -
mass of object 1- [
kg] ma -
mass of object 2 [
kg] f- 2 :-<
r distance between the centres of the 2 objects (m)
-
eg .
The earth has a radius C 6138 ✗ 106m) and is 3,844 ✗ 108m from the Moon which has a radius at 11737 ✗ 106m .
If the
"
mass of the earth is 5,97×102 kg and the moon 735×10
"
kg Determine
,
the gravitational force experienced between the planets :
6min L
F =
v2
( 6,7×10
" "
) ( 5,97×102 4) (7,35×1022)
3,844 ✗108
=
6,38 ✗ 106 1,737×106
.
>< >< . ( 6,38×106+3,844×108 + 1,337 ✗ 106 ) 2
=
102°
Neg
1,91 ✗
.
An asteroid with a mass of 200 tons passes between the earth and the moon . The centre 0C the asteroid is 3,91 ✗ 108m
from the centre ol the earth and 1,91 ✗ 106m from the centre at the noon . Determine the resultant force acting on the asteroid:
force 0L Earth on asteroid force of moon on asteroid
) (5,97×1024) (200×103) 1) (7,35×1032) (200×103)
- '
Fea ( 6,7×10
"
Fma = ( 6,7×10
_
=
(3,91 × 108) 2 ( 1 as ✗
,
106 ) l
3,91 ✗ 108 ,, at ✗ 106
¢
= =
523,27N towards the Earth 269976,15N towards moon
- : fret =
269 976,1s -523,27=269 452,88 N towards the noon
GRAVITATIONAL FIELDS -
toraacnngpeuniimass
(a in space where force
region a mass experiences a .
always a force ol ATTRACTION pulls -
bodies towards the centre of the earth
( Nkg )
'
g- gravitational field strength
'
g
=
É f- force experienced by the object ( N)
M -
mass ol the object Ckg
The strength of the gravitational field will be it the mass ol the planet is large and it will decrease with increasing distance from the at the planet
greater centre