CAMBRIDGE A LEVEL PHYSICS DETAILED NOTES - GRAVITATIONAL FIELD

GRAVITATIONAL FIELD

he attractive force
↑
between the point masses is

directly proportional to the product of the 2 masses

and inversely proportional to square of their
separation.
N eWtOn's

Law of
F He Gravitational constant
~
·




1 F Mz I
Gravitation = 6.67 x 10 "NM2 15-2
=




unit: N




ten
strength of
g-field
·


her?

Fg M2; test mass
q ⑧




i
granational


I


Field Graw, force unit mass (En)
per
g: Tig
9
=
M2 > Fg= AM
strength
g ↳9 4 fre
1. g=#II

so
9.8 1

unit: N19 "M5- was
field strength of M1,
grav,
at a distance from centre



~

, g
=
GM- '
'


!
'




%
'

i.

9=9-1%7
"




REY
.




↑
" "




"+
to R
since his small compared :
'
1 1
i '




19 a-fg-i-9.HN ; i.
-1


Planet 's
= kg

Note : For
large R
g- field constant
cuz lines are always parallel
surface
3h
¥ # t.tt
T T T
Ir
9.81111kg
-1

radial uniform




I Assumptions
of earth
:


Uniform
1) density TS
7¥ TRE 2) surface of earth is uniform ,


uniform sphere
I
Earth is a


Inside
1
* at centre of Earth ,



9.81 - -
- -




9=0

Planet 's
m
r↓
of planet
attracting us↓→rRE
←
¥É > RCM )

Surface once inside E ,

M =
pv
1) density p % →


}
,
=
mar
M ✗P

2) Volume ,
V =
g- Xp }
→ ✓ xp ,




3) g
=
9¥ →
g ✗ % + map



garriga r