Hello guys n gals 
here is some useful info on gravitation....
1. 2 falling bodies of different masses reach the earth in same time. two bodies of differnt volumes & same mass
will not reach simultaneously. body of smaller volume will reach earlier bcoz upthrust on
smaller volume < upthrust in larger volume.
2 .If a body is taken above the surface of earth, g is proportional to 1/r ^2 .
but if a body is taken inside the earth , g decreases linearly with distance frm the centre of earth.
3. g is min at mercury , max at jupiter
4.Radius of pole > radius of equator (by 21 km)
5.If earth stops rotating , there will be increase in g at equator by a value Rw^2 = 0.034 m/s^2
6.If rate of rotation of earth increases , g decreases everywhere except at poles.
7. Orbital velocity of satellite is independent of mass of satellite , depends on mass and radius of planet ,
inversely proportional to ht of satelliteand its direction its direction is along tangent to the orbital path.
8. Orbital velocity of satellite close to earth = 7.92 km/s
9.Escape velocity from earth = 11.2 km/s and from sun = 618 km/s
10. Escape velocity does not depend on mass of satellite , angle of projection
11.If a body moves with velocity v ( > escape vel.u ) ,then its vel. in space = square root of ( v^2 - u^2)
12. A planet will have atmosphere if RMS velocity of molecules is smaller than escape velocity.
13. g increases from equator to pole due to rotation
14. Ht of geostationary satellite = 36000 km and polar satellite = 1000 km
15. Angular velocity of a satellite orbitting close to earth = 2pie/T =0.001237 rad/sec
16.Relative velocity of geostationary satellite w.r.t. earth = 0 m/s
17.Equatorial orbits are called parking orbits
18. When a satellite is orbitting in its orbit , no energy is reqd to keep it in its orbit
19. When a body is projected horizontally with vel. v from any ht . from the surface of earth :
a] if v < vo , body returns to earth
b] if v= vo , body revolves in circular path
c] if vo<v<ve , the body will revolve in elliptical orbit
d] if v = ve , the body will escape the gravitational pull
e] if v > ve , the body will escape following a hyperbolic path with vel. = square root of ( v^2 - ve^2)
here ve = escape vel. and vo = orbital vel.
20. When a body falls freely from infinite ht. it will reach the surface with vel = 11.2 km/s
21.If velocity of satellite orbitting the earth is increased by 41.4 % or its kinetic energy is doubled , then it will escape from gravitional pull
of earth
22. For a satellite in circular orbit , P.E.> K.E
23. When velocity of satellite is increased , its T.E will increase & start orbitting in a circular path of larger radius.
24. When ht. of satellite increases,P.E INCREASES , K.E DECREASES
25.When T.E of of satellite is
1] - ve it will move in circular/elliptical orbit
2] 0 it will escape from orbit and path becomes parabolic
3] + ve it will escape from orbit and path becomes hyperbolic
26. The value of g will be half of its value at the surface of earth at a ht =( square roott2 - 1)radius of earth.
27.When a planet is revolving in an elliptical orbit, angular momentum and total energy is conserved.
28.If radius of earth shrinks by 1%, its mass remaining the same, g will increase by 2 %.
29.Tidal effect is inversely proportional to cube of distance.
30.If a man goes from surface of earth to a ht = radius of earth , then his relative wt w.r.t earth = 1/4 th
31.If a projectile is fired with velocity v , then sum of P.E & K.E. is
1] +ve for v > ves ,where ves =escape vel
2]-ve for v< ves
3] 0 for v = ves
Back to Community Shelf
12 Nickels awarded!![[Post New]](/templates/default/images/icon_minipost_new.gif){kind=icon}
177
