# Case Study Questions for Class 11 Physics Chapter 8 Gravitation

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## Case Study Questions for Class 11 Physics Chapter 8 Gravitation

Here we are providing case study questions for class 11 physics chapter 8 Gravitation. Students can practice these questions for better understanding of case study type questions.

Case Study Questions:

Question 1:

Earthâ€™s Satellite
Earth satellites are objects which revolve around the earth. Their motion is very similar to the motion of planets around the Sun. In particular, their orbits around the earth are circular or elliptic. Moon is the only natural satellite of the earth with a near circular orbit with a time period of approximately 27.3 days which is also roughly equal to the rotational period of the moon about its own axis. Also, the speed that a satellite needs to be travelling to break free of a planet or moonâ€™s gravity well and leave it without further propulsion is known as escape velocity. For example, a spacecraft leaving the surface of earth needs to be going 7 miles per second or nearly
25000 miles per hour to leave without falling back to the surface or falling into orbit.

(i) The ratio of escape velocity at earth (ve) to the escape velocity at a planet (vp), whose radius and mean density are twice as that of earth is
(a) 1:2âˆš2
(b) 1: 4
(c) 1: âˆš2
(d) 1: 2

(ii) Gas escapes from the surface of a planet because it acquires an escape velocity. The escape velocity will depend on which of the following factors?
(a) Mass of the planet
(b) Mass of the particle escaping
(c) Temperature of the planet
(d) None of the above

(iii) The escape velocity of a satellite from the earth is ve. If the radius of earth contracts to (1/4)th of its value, keeping the mass of the earth constant, escape velocity will be
(a) doubled
(b) halved
(c) tripled
(d) unaltered