Prof. Yogesh Jahagirdar’s
Academy of Physics
Template
Gravitation
Assignment -1
ASGN-1
1
1. Valu e of ‘G ’ on th e U ranus is
a) d iffe rent fro m that on ea rth, s inc e it is farthe r f ro m s un
b) same as that on ea rth.
c) greate r than that on ea rth
d) less tha n that on earth, s inc e it is fa rthe r f rom sun.
2. The value o f acceleration due to g rav it y on the surface of ea rth be deno te d by ‘g ’.
If the rad ius o f the ea rth is 6400 kilomete rs , then the value of acc elerat ion due to
gravity 3200 km above the surfa ce o f earth is
a) 2/3 g
b) 4/9 g
c) g /2
d ) 2g
3.
If the rad ius of ea rth dec reas es b y 3%, and its mass in creas es by 3 %, the acceleratio n
due to gravity on the surfa ce o f the earth
a) w ill increase by 9%
b ) will decrease by 9%
c) w ill d ecre ase by 3%
d ) will in creas e by 6%
4.
A sp ring is sus pended vertica lly fro m a rig id supp ort. It e lon gate s due to a ma ss
hang ing fro m it. If the ea rth s hrin ks in its rad ius by 2% its mass re ma in ing c onstant,
the
elongat ion in the spring
a) increases by 3%
b ) decre ases by 2%
c) rema in s the same
d ) increase s by 4%
5.
If e arth we re a ho llow sp here , the in te ns it y of g rav itationa l fie ld ins ide it is
a) 9.8 N kg - 1
b) ze ro
-1
c) greate r tha n 9.8N kg
d) less tha n 9.8 N kg - 1
6.
If a planet exists whos e mass is th ree times that of the earth and its radius is three
times tha t of th e earth then a 6 kgwt(on e arth ) mass on its s urface would we ig h
a) 2kgwt
b) Zero
c) 6kgwt
d ) 9.8 kgwt
7. The intensity of g ravitat iona l f ie ld of the earth is min imu m
a) at the e quato r
b) at the po les
c) between equator and po les
d) non e of the above
8.
If the dens it y of the earth become ha lf but th e rad ius re ma ins the same, then the value
of g on its surface will be
a) 2g
b) g/2
c) 3g /2
d ) g/4
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9. Th e va lue of accelera t io n du e to g ravity on
in g p . Fo r a bod y situa ted s ligh tly a b ove or
g canno t be e qual to
a) g p
c) bo th g p and g eq
2
equa to r of e a rth is g eq and that on the poles
below the surface of ea rth, the magn itu de of
b) g e q
d) non e of the above
10. A mis sile, of mas s 50kg, is orb it in g clo se to the s urface of th e earth, the n its
mo mentum is
a) 4 × 1 0 4 kg -m/s b) 4 × 1 0 5 kg -m/s
c) 1.6 × 10 5 kg-m/s d ) 2 × 10 5 kg -m/s
11. The mass of the moon is 1/8 1 of earth ’s mass and its rad iu s ¼ that of the ea rth. The
crit ic a l veloc ity of sa te llite ve ry c lose to moon w ill
a) 0.5 k m pe r se c b) 1.75 km pe r s ec
c) 2.5 km pe r s ec
d) 5.0 km pe r se c
12. Two satellites of masses m 1 and m 2 (m 1 > m 2 ) are revo lving round th e earth in c irc u la r
orb its o f rad ius r 1 and r 2 (r 1 < r 2 ) res pective ly. If P 1 and P 2 are mo mentu m of the two
satellite s then
a) P 1 =P 2
b) P 1 <P 2
c) P 1 >P 2
d ) cannot b e determined
13. The height of the b ody a bove the surfac e where accelera tion d ue to g ravit y dec reas es
by 2% is
a) R/500
b) R/100
c) R/400
d ) R/200
14. Three mass es (m) a re p laced at the v ert ic es o f an e quilate ra l triang le, o f sid e x. T he
intensit y of g rav itationa l f ie ld at t he c entroid is
a) 0
b) 3Gm /x 2
c) 3Gm /2x 2
d ) 2G m/3x 2
15. The dista nce b etween two masses 2m an d 8m, is distance d. The d istance of a p oin t
fro m the la rge r whe re the grav itat ion a l fie ld is zero is
a) 2d/3
b) d/3
c) d/2
d ) 15d/1 6
16. The mass of th e planet is 3 × 10 2 8 kg a nd the rad ius is 6 × 1 0 6 m. The Acceleration due
to gravity on its surface is
a) 5.5  10 4 m/s 2 b) 7.6  10 4 m/s 2
c) 5.5  10 3 m/s 2
d ) 7.6  10 3 m/s 2
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Academy of Physics
3
17. The mo men tu m o f a satellite , o f mas s m, orb it in g very clos e to a planet, o f d ensity 
and rad ius R, is
a)
πGρR 2 m 2
3
b)
4 πGρR 2 m
3
c)
4 πGρR 2 m 2
3
d)
πGρR 2 m
3
18. The height fro m the surface of the eart h a t wh ic h the gravitationa l force is one fou rth
of th at at th e su rface of the earth , is (R = 64 00 km)
a) 1600 km
b) 320 0km
c) 64 00km
d ) 12800km
19. A s tatio nary satellite of the ea rth is at a height of 3585 0 km fro m the surface of the
earth. The cen tripeta l ac cele rat io n at that height w ill be
a) 0.22 m/s 2
b) 0.56 m/s 2
c) 0.78m/s 2
d ) 0.99 m/s 2
20. The va lue of acc ele rat ion due to g ravity on po les o f earth is g a nd that on th e eq uato r
is g eq . If the period of sp in, of e arth about itself, dou b les , then the values of
acce leration due to grav ity on po les a nd o n equ ator w ill be respe ctively,
a) <g, < g eq
b) =g, < g e q
c) <g, = g e q
d ) =g, > g eq
21. If  is the density of the p lan et, R is the rad iu s, the n the g ravitationa l fo rc e on a ma ss
m p laced at a d ista nce of R/3 from the surface is
a)
3πGρRm
16
b)
3πGρRm
4
c)
4 πGρRm
3
d)
9 πGρRm
16
22. Fo ur ma sses each 2kg are p lac ed at the vertices of a square of side 2m.
The acc ele rat ion due to grav ity be ca use of th ese mas ses, at the center of the square,
is
a) 42 G
b) 2 G
c) 2 G
d) 0
23. Two satellites, X and Y, are orbiting, in clockwise direction, around a planet at a height of 3R and 8R, in
the same plane. At the instant, when they are collinear with the centre of the earth, the relative velocity
of X w.r.t Y is ( velocity of the satellite very close to the surface of the planet is V)
a)V/2
b) V/6
c) V/3
d) V/4
24. A s atellite o rb iting a rou nd ea rth, is placed in a d iffe ren t o rb it, wh ere its critica l veloc ity
bec omes two times. The gra vitat io na l fo rce on the satellite w ill be
a)2 times
b) 4 times
c) 16 times
d) 32 times
25. The centripetal acceleration of a satellite at a height of 3R will be ( g = acceleration due to gravity at
the surface)
a)9g /12
b) g/16
c) g/9
d) g/4
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