11 th Std Phy Unit 5

If R is radius of the earth and g the acceleration due to gravity on the earth s surface. The mean density of the earth is If R is radius of the earth and g the acceleration due to gravity on the earth s surface. The mean density of the earth is

2 Mark(s)

4πg/2GR 4πg/2GR
3πR/4gR 3πR/4gR
3g/4πRG 3g/4πRG
4GR/3πg 4GR/3πg

If the earth rotates faster than its present speed. The weight of an object will If the earth rotates faster than its present speed. The weight of an object will

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Increase at the equator but remain unchanged at the pole
Decrease at the equator but remain unchanged at the poles
Remain unchanged at the equator but decrease at the poles
Remain unchanged at the equator but increase at the poles

If the radius of a planet is 'R' and density' ρ', then the escape velocity' V_e' of any body from its surface will be proportional to If the radius of a planet is 'R' and density' ρ', then the escape velocity' V_e' of any body from its surface will be proportional to

2 Mark(s)

R/√ρ R/√ρ
R√ρ R√ρ
ρR ρR
√ρ/R √ρ/R

A tunnel is dug along a chord of the earth at a perpendicular distance R/2 from the centre of earth. The wall of the tunnel may be assumed earth. The wall of the tunnel may be assumed to be frictionless. A particle is released from one end of the tunnel. The pressing force by the particle on wall is depicted by the graph A tunnel is dug along a chord of the earth at a perpendicular distance R/2 from the centre of earth. The wall of the tunnel may be assumed earth. The wall of the tunnel may be assumed to be frictionless. A particle is released from one end of the tunnel. The pressing force by the particle on wall is depicted by the graph

2 Mark(s)

The escape velocity from the surface of earth of mass 'M' and radius 'R' is 'V_e'. The escape velocity from the surface of a planet whose mass and radius are 3 times that of the earth, will be The escape velocity from the surface of earth of mass 'M' and radius 'R' is 'V_e'. The escape velocity from the surface of a planet whose mass and radius are 3 times that of the earth, will be

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Ve Ve
3Ve 3Ve
12Ve 12Ve
9Ve 9Ve

The escape velocity from earth is 11.4 km/s. If a body is to be projected in a direction making an angle 45° to the vertical, then the escape velocity is The escape velocity from earth is 11.4 km/s. If a body is to be projected in a direction making an angle 45° to the vertical, then the escape velocity is

2 Mark(s)

11.2×2km/s 11.2×2km/s
11.2km/s 11.2km/s
11.2/√2km/s 11.2/√2km/s
11.2√2km/s 11.2√2km/s

If a satellite is travelling in the same direction as the rotation of earth i.e., west to east, what is the interval between two successive times at which it will appear vertically overhead to an observer at a fixed point on the equator? If a satellite is travelling in the same direction as the rotation of earth i.e., west to east, what is the interval between two successive times at which it will appear vertically overhead to an observer at a fixed point on the equator?

2 Mark(s)

7417 s 7417 s
6831 s 6831 s
5082.9 s 5082.9 s
1 day 1 day

In above question No. 275, the gravitational potential at the midpoint of the line joining the centers of the spheres is In above question No. 275, the gravitational potential at the midpoint of the line joining the centers of the spheres is

2 Mark(s)

Zero Zero
−GM/r −GM/r
−2GM/r −2GM/r
−4GM/r −4GM/r

Two satellites A and B go around a planet P in circular orbits having radii 4R and R respectively. If the speed of satellite A is 3V, the speed of the satellite B would be Two satellites A and B go around a planet P in circular orbits having radii 4R and R respectively. If the speed of satellite A is 3V, the speed of the satellite B would be

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6 V 6 V
4 V/3 4 V/3
3 V/2 3 V/2
12 V 12 V

A system of binary stars of masses mAmA and mB are moving in circular orbits of radii rA and rB respectively. If TA and TB are the time periods of masses mA and mBmB respectively then A system of binary stars of masses mAmA and mB are moving in circular orbits of radii rA and rB respectively. If TA and TB are the time periods of masses mA and mBmB respectively then

2 Mark(s)

Universal law of gravitation is derived from Universal law of gravitation is derived from

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Kepler's law Kepler's law
Aryabhatta's law Aryabhatta's law
Einstein's equation Einstein's equation
Newton's laws of motion Newton's laws of motion

The energy spent in sending a body of mass 1 kg surface of the earth to infinity is, if escape velocity from the surface of the earth is 12 km/s. The energy spent in sending a body of mass 1 kg surface of the earth to infinity is, if escape velocity from the surface of the earth is 12 km/s.

2 Mark(s)

12×10^6 J 12×10^6 J
144×10^6J 144×10^6J
6×10^6 J 6×10^6 J
72×10^6 J 72×10^6 J

Two satellites A and B having ratio of masses 3:1 are revolving in circular orbits of radii 'r' and '4r'. The ratio of total energy of satellites A to that of B is Two satellites A and B having ratio of masses 3:1 are revolving in circular orbits of radii 'r' and '4r'. The ratio of total energy of satellites A to that of B is

2 Mark(s)

0.12569444444444 0.12569444444444
0.12777777777778 0.12777777777778
0.04375 0.04375
0.50069444444444 0.50069444444444

What is the percentage decrease in the weight of a body when it is taken to a height of 32 km from the surface of earth? What is the percentage decrease in the weight of a body when it is taken to a height of 32 km from the surface of earth?

2 Mark(s)

0.005 0.005
0.02 0.02
0.015 0.015
0.01 0.01

The depth of which acceleration due to gravity becomes g/n (R = radius of earth, g = acceleration due to gravity, n = integer) The depth of which acceleration due to gravity becomes g/n (R = radius of earth, g = acceleration due to gravity, n = integer)

2 Mark(s)

Rn/n−1 Rn/n−1
n/R(n−1) n/R(n−1)
R(n−1)/n R(n−1)/n
n−1/nR n−1/nR

11 th Std Phy Unit 5 : Question 1 of 15