Q.1
The angular speed of earth in rad/s, so that the object on equator may appear weightless ( g=10 m/s2 and radius of earth=6400 km) [ AMU PMT 1997]
  • a) 1.56
  • b) 1.25 × 10⁻¹
  • c) 1.56 × 10⁻³
  • d)1.25 × 10⁻³
Q.2
The value of g at a particular point is 9.8 m/sSuppose the earth suddenly shrinks to half its present size, without losing any mass. The value of g at the same point ( assume that distance of point from the center of earth does not shrink) will be [ Pb. CET 1998]
  • a) 4.9 m/s²
  • b) 3.1 m/s²
  • c)9.8 m/s²
  • d)19.6 m/s²
Q.3
The mass of the moon is about 1.2% of the mass of the earth. Compared to the gravitational force the earth exerts on the moon, the gravitational force the moon exerts on earth [ SCRA 1998]
  • a) is the same
  • b) is smaller
  • c) is greater
  • d) varies with its phase
Q.4
The escape velocity of rocket on the earth is 11.2 km/s. Its value on a planet where acceleration due to gravity is double that on the earth and diameter of the planet is twice that of the earth will be in km/s [ M.N.R. 1999]
  • a)11.2
  • b) 5.6
  • c)22.4
  • d)33.6
Q.5
If the radius of earth were to decrease by 1%, its mass remains same, the acceleration due to gravity on the surface of earth will [ IIT 1981]
  • a) increase by 1%
  • b) increase by 2%
  • c) decrease by 1%
  • d)decrease by 2%
Q.6
How much energy will be necessary for making a body of 500 kg escape from the earth? ( g=9.8 km/s2, radius of the earth=6.4 × 106m) [ M.P. CEE 1999]
  • a) About 9.8 × 106 J
  • b) About 6.4 × 108 J
  • c) About 3.1 × 1010 J
  • d) About 27.4 × 1012 J
Q.7
What should be the velocity of earth due to rotation about its own axis so that the weight of person become 3/5 of the present weight at equator. Radius of earth on equator is 6400km [ MNR 1999]
  • a) 7.4 × 10⁻³ rad/s
  • b) 6.7 ×10⁻⁴ rad/s
  • c) 7.8 × 10⁻⁴ rad/s
  • d) 8.7 × 10⁻⁴ rad/s
Q.8
If both the mass and the radius of the earth decreases by 1% [ karnataka CET 2001]
  • a) the escape velocity would increase
  • b) the acceleration due to gravity would increase
  • c)the escape velocity would decrease
  • d)the acceleration due to gravity would decrease
Q.9
The escape velocity on the surface of earth is 11.2km/s. What would be the escape velocity on the surface of another planet of same mass but 1/4 times the radius of the earth? [JIPMER 2002]
  • a) 22.4 km/s
  • b) 67.2 km/s
  • c)44.8 km/s
  • d) 89.6 km/s
Q.10
A satellite orbits around the earth in a circular orbit with speed v and orbital radius r. If it loses some energy, then v and r changes as [ JIPMER 2009]
  • b) both v and r decreases
  • a) v decreases as r increases
  • c)v increases and t decreases
  • d)both v and r increases
Q.11
The acceleration due to gravity on the planet A is 9 times the acceleration due to gravity on planet B. A man can jump to a height of 2m on the surface of A. What is the height of jump by the same person on the planet B [ CBSE PMT 2003]
  • a) 2/9 m
  • b) 18 m
  • c) 6 m
  • d) 2/3 m
Q.12
A satellite with kinetic energy E is revolving round the earth in a circular orbit. The minimum additional kinetic energy required for it to escape into outer space is [ kerala PMT 2003]
  • a)√2 × E
  • b) 2E
  • c)E/ √2
  • d)E
Q.13
A satellite S is moving in an elliptical orbit around the earth. The mass of the satellite is very small compared to the masses of earth... [ IIT 1998]
  • a) The acceleration of S is always directed towards the center of the earth
  • b) The angular momentum of S about the center of the earth changes in direction but its magnitude remains constant.
  • c)The total energy of S varies periodically with time
  • d)The linear momentum of S remains constant in magnitude
Q.14
A satellite is moving around the earth with speed v in a circular orbit of radius r. If the orbit radius is decreased by 1% its speed will be [ Roorkee 1995]
  • a) increased by 1%
  • b) decrease by 0.5%
  • c)increased by 0.5%
  • d)decreased by 1%
Q.15
The masses and radii of the earth and moon are M1, R1 and M2, R2 respectively. Their centers are distance d apart. the minimum speed with which a particle of mass m should be projected from a point mid way between the two centers so as to escape to infinity is
  • a)
    ch-7_qn-124choice_img_no1.png
  • b)
    ch-7_qn-124choice_img_no2.png
  • c)
    ch-7_qn-124choice_img_no3.png
  • d)
    ch-7_qn-124choice_img_no4.png
Q.16
A rocket is launched vertically from the surface of earth with an initial velocity u the height up to which the rocket can go from the surface of earth, before falling back is
  • a)
    ch-7_qn-125choice_img_no1.png
  • b)
    ch-7_qn-125choice_img_no2.png
  • c)
    ch-7_qn-125choice_img_no3.png
  • d)
    ch-7_qn-125choice_img_no4.png
Q.17
Two concentric shells of uniform density having mass M1 and M2 are situated as shown in the figure. The force on the particle of mass m when it is located at r=b is
ch-7_que_no-126_img_no1.png
  • a)
    ch-7_qn-126choice_img_no1.png
  • b)
    ch-7_qn-126choice_img_no2.png
  • c)
    ch-7_qn-126choice_img_no3.png
  • d)
    ch-7_qn-126choice_img_no4.png
Q.18
in the 126 question, the gravitational potential energy of the particle at P is ..
  • a)
    ch-7_qn-127choice_img_no1.png
  • b)
    ch-7_qn-127choice_img_no2.png
  • c)
    ch-7_qn-127choice_img_no3.png
  • d)
    ch-7_qn-127choice_img_no4.png
Q.19
The metallic bob of a simple pendulum has the relative density ρ. The time period of this pendulum is T. If the metallic bob is immersed in water, then the new time period is given by [ SCRA 1998]
  • a)
    ch-7_qn-128choice_img_no1.png
  • b)
    ch-7_qn-128choice_img_no2.png
  • c)
    ch-7_qn-128choice_img_no3.png
  • d)
    ch-7_qn-128choice_img_no4.png
Q.20
A satellite is moving in a circular orbit at a height 100km above the earth's surface. A person inside the satellite feels weightless because [ CSEP 1999]
  • a)acceleration due to gravity is almost zero at such a height
  • b) the earth does not exerts any force on the person
  • c)the centripetal force makes the satellite move in circular orbit
  • d)the force due to earth and moon are almost compensated at such height
Q.21
Four particles, each of mass m, are moving along a circle of radius r under the influence of mutual gravitational attraction. The speed of each particle will be
  • a)
    ch-7_qn-130choice_img_no1.png
  • b)
    ch-7_qn-130choice_img_no2.png
  • c)
    ch-7_qn-130choice_img_no3.png
  • d)
    ch-7_qn-130choice_img_no4.png
Q.22
A body is projected vertically upwards from the surface of a planet of radius R with velocity equal to half the escape velocity for the planet. The maximum height attended by the body is [ karnatak CET 2002]
  • a) R/2
  • b) R/3
  • c)R/5
  • d)R/4
Q.23
The period of moon's rotation around the Earth is nearly 29 days. If moon's mass were 2 fold of its present value, all other things remain unchanged, the period of moon's rotation would be nearly [ kerala CET 2002]
  • a) 29√2
  • b) 29 / √2
  • c) 29×2
  • d) 20 days
Q.24
A planet has a mass 225 times and a radius 9 times that of the earth. The escape velocity for earth is known to be 11.2 km /s. The escape velocity for the planet is then [ Hariyana CET 2002]
  • a)2.24 km/s
  • b) 5 km/s
  • c)56 km/s
  • d) 280 km/s
Q.25
A point P lies on the axis of a ring of mass M and radius a, at a distance a from its center C. A small particle starts from P and reaches C under gravitation only. Its speed at C will be
  • a)
    ch-7_qn-134choice_img_no1.png
  • b)
    ch-7_qn-134choice_img_no2.png
  • c)
    ch-7_qn-134choice_img_no3.png
  • d)zero
Q.26
Two small satellites move in a circular orbits around the earth, at distance r and (r + dr) from the center of the earth. Their time periods of rotation are T and T + dT ( Δr << r , ΔT << T) Then
  • a)
    ch-7_qn-135choice_img_no1.png
  • b)
    ch-7_qn-135choice_img_no2.png
  • c)
    ch-7_qn-135choice_img_no3.png
  • d)
    ch-7_qn-135choice_img_no4.png
Q.27
A satellite moves in a circle around the earth. The radius of this circle is equal to one half of the radius of the moon's orbit. The satellite completes one revolution in.. [ J and K CET 2005]
  • a) (1/2) lunar month
  • b) (2/3) lunar month
  • c) 2-3/2 lunar month
  • d) 23/2 lunar month
Q.28
If a rocket is to be launched from the surface of the earth so as to escape from the earth altogether, then
  • a)it can have any velocity at start
  • b) it must have a minimum velocity of 11.2 km/s
  • c)the minimum velocity at start will be 11.2 km/s it it shoots up ony vertically
  • d)none of above
Q.29
The ratio of the radii of the planet P1 and P2 is kThe ratio of the acceleration due to the gravitation on them is kThe ratio of the escape velocities from them will be
  • a) k1k2
  • b) √(k1k2)
  • c) √(k₁ / k₂)
  • d) √(k₂/ k₁)
Q.30
The orbital speed of Jupiter is
  • a) greater than the orbital speed of earth
  • b) less than the orbital speed of the earth
  • c)equal to the orbital speed of the earth
  • d)zero
0 h : 0 m : 1 s