Flashcards
gravitation
Cards in this deck (30)
- 1newton's law of gravitationthe force b/w any two massive bodies is directly proportional to the product of their masses and inversely proportional to the square of the distance b/w them.
- 2cavendish discoveredthe value of G i.e. (6.67 * 10^-11) Nm2/Kg2
- 3properties of gravitational forces1) central force
2) attractive in nature
3) long and short distance both
4) does not depend upon the medium
5) weakest force
6) inverse square law - 4superposition principleunder root F1+F2+ F1F2cos theta
- 5force on point mass due to ringFnet= GMmx/(R^2+x^2)^3/2
where x is the distance b/w mass and ring
R radius of the ring
M mass of the ring
m is point mass - 6in the above case, if x<<Fnet = GMmx/R^3
for maximum force x=+-R / root 2 - 7gravitational fieldit is the field surrounding the point mass up to which it's influence can be experienced
- 8gravitational field intensityit is defined as the force per unit mass
S.I. unit is N/kg or m/s^2 - 9earth's gravitational field intensityIg=F/m=GMe/Re^2=g
- 10variation of small g with heightit decreases with an increase in height.
g(height)=g[R/R+h]^2
gh=g[1-2h/R] * for small height
delta g/g=2H/R - 11variation with depthit decreases with an increase in depth.
g(depth)=g[Re-d/Re]
gd=g[1-d/Re] - 12for small height and depth2H=d
- 13variation due to rotationg'=g-w^2Rcos^2theta
gp-ge=w^2R=0.03 m/s^2
the effect at poles and equator is mainly 60 percent due to rotation and 40 percent due to shape - 14variation due to shapeg equater
- 15when the earth starts rotating then the value of g increasesit increases everywhere except the pole
- 16if the earth starts rotating with angular speed more than it's present value then the value of gdecreases everywhere except the poles
- 17if the value of g becomes 0 at the equator then the angular speed of earth becomes17 times more than it's natural speed and time period becomes 84.6 min or 1.4 hr
- 18gravitational intensity for a solid sphereoutside= Ia= -GM/r^2
on the surface=Ib =-GM/r^2
inside= Ic= -GM/R^3 - 19graph for gravitational intensity for a solid sphere
- 20gravitational intensity due to the hollow sphere plus graphinside = zero
outside =same as that of a solid sphere
on the surface= same as that of the solid sphere
- 21gravitational potentialit is defined as the amount of work done per unit mass in bringing it from infinite to the desired point
Vg=W/m
S.I. unit is J/Kg or volt
it is a scaler quantity - 22gravitational potential due to a solid sphereinside-v=GM/2R^3*[3R^2-r'^2]
on the surface-v=-GM/R
outside-v=-GM/r
at centre-3/2*Vsurface
- 23gravitational potential due to a hollow sphereinside-V=-GM/R
surface-V=-GM/R
outside=-GM/r
- 24work done to take a body from earth to height RW=mgh/1+h/Re
if h<<< - 25maximum height attained by a particleh=v^2 Re/2gRe-V^2
- 26escape velocitymin. the velocity required by the particle to escape the gravitational field of a planet.
for escaping any planet it's total energy should be 0 or it's escaping energy should be -ve of total energy. - 27escape velocity from earth's surfaceVe=11.2 km/s
- 28escape velocity does not depend uponmass of projection
angle of projection - 29if the speed of gases is greater than the escape velocity-gases will escape out
-a balloon filled with helium will move downwards
-if a particle is projected with a velocity less then escape velocity then the height attained is h=V^2r/2gR - 30if v is greater than Ve if particles projected with velocity V1 and after moving in space it is V2 thenV2= root V1^2-Ve^2
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- class 12 physics Flashcards on gravitation, created by sakhi rathore on 07/09/2020.
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- sakhi rathore · Sep 2020
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- Sep 7, 2020
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