Our mission is to provide a free, world-class education to anyone, anywhere. A satellite is to be placed in equatorial geostationary orbit around earth for communication. (a) Pascal Question 10. Here we have provided NCERT Exemplar Problems Solutions along with NCERT Exemplar Problems Class 11. Physics Notes Class 11 CHAPTER 8 GRAVITATION Every object in the universe attracts every other object with a force which is called the force of gravitation. Initial potential energy at the surface of earth = GMem/’r. QUESTIONS FROM TEXTBOOK. You also get idea about the type of questions and method to answer in your Class 11th examination. The value of G is 6.67 X 10-11 Nm 2 kg-2 and is same throughout the universe. Gravitation Class 9 Extra Questions Very Short Answer Type. of space ship is zero, therefore. Does the escape speed of a body from the Earth depend on (a) the mass of the body, (b) the location from where it is projected, (c) the direction of projection, (d) the height of the location from where the body is launched? A star like the sun has several bodies moving around it at different distances. Here we have given NCERT Exemplar Class 11 Physics Chapter 7 Gravitation. The term gravity is used for gravitation, but gravitation is defined as the theory that explains the attraction while gravity is defined as the force that pulls objects towards each other. (c) mass of the body If m is the mass of the space-ship, then Potential energy of space-ship due to gravitational attraction of the Sun = – GM m/R Potential energy of space-ship due to gravitational attraction of Mars = – G M’ m/R’ Since the K.E. NCERT Exemplar Class 11 Physics is very important resource for students preparing for XI Board Examination. (b) Acceleration due to gravity increases/decreases with increasing depth (assume the Earth to be a sphere of uniform density). Question 8.7. In other words, distant stars would rise 4 minutes early every successive day. Therefore, the tidal effect of Moon’s pull is greater than the tidal effect of the sun. Gravitational forces are independent of medium. An astronaut inside a small spaceship orbiting around the earth cannot detect gravity. Mass of the satellite = 200 kg; mass of the earth = 6.0 x  1024 kg; radius of the earth = 6.4 x  106 m; G = 6.67 x  10-11 N m2 kg-2. 13. A body of mass 1kg is attracted by the earth with a force which is equal to. (e) Potential energy varies along the path. Khan Academy is a 501(c)(3) nonprofit organization. For the motion of another planet like mercury as observed from earth, this would. Let us assume that our galaxy consists of 2.5 x 1011 stars each of one solar mass. Physics Important Questions Class 11 are given below. (c) Comet has constant angular momentum. (c) That the acceleration due to gravity on earth is the same for all bodies is due to the equality of gravitational mass and inertial mass. Initial potential between two stars, r =  109 km =  1012 m. (b) are always at the same point only for spherical bodies. 2. Answer: Question 8. 1. (c) Buoyant force Question 11. Final potential energy of two stars = -GMm/2R For the above problem, the direction of the gravitational intensity at an arbitrary point P is indicated by the arrow (i) d, (ii), e, (iii) f (iv) g. If you have any query regarding NCERT Solutions for Class 11 Physics Chapter 8 Gravitation, drop a comment below and we will get back to you at the earliest. 2. Will an object placed on its equator remain stuck to its surface due to gravity? But it is the apple that falls towards the earth and not vice-versa. Answer:  Let gh be the acceleration due to gravity at a height equal to half the radius of the Earth (h = R/2) and g its value on Earth’s surface. 24. M be the mass of the Sun and M’ be the mass of Mars. If so, is the equilibrium stable or unstable? (d) more. However, the tidal effect of the Moon’s pull is greater than the tidal effect of Sun. At what distance from the earth’s centre is the gravitational force on the rocket zero? Answer: Using the explanation given in the solution of the previous problem, the direction of the gravitational field intensity at P will be along e. So, option (ii) is correct. 9.8N. (d) thrust. Answer: (a) No. What should be done if this satellite has to be transferred to a circular orbit of radius 6R . Question 8. Draw areal velocity versus time graph for mars. (a) The escape speed of a body from the Earth does not depend on the mass of the body. You are expected to do all the questions based on this to remain competitive in IIT JEE examination. (d) Kinetic energy does not remain constant. Is an object placed at that point in equilibrium ? (a) planets will not have elliptic orbits. question_answer 11) According to Newton's law of gravitation, the apple and the earth experience equal and opposite forces due to gravitation. Can we shield a body from the gravitational influence of nearby matter by putting it inside a hollow sphere or by some other means? Mean solar day is the time interval between two successive noon when sun passes through zenith point (meridian). Assume that earth’s spin axis is normal to its orbital plane and find out the length of the shortest and the longest day. Certain stellar objects called pulsars belong to this category). .•. How much energy must be expended to rocket the satellite out of the earth’s gravitational influence? (b) circular orbits of planets is not possible. NCERT Solutions for Class 11 Physics Chapter 8 Gravitation are part of Class 11 Physics NCERT Solutions. 11. (You can check this yourself using the data available in the succeeding exercises). Before starting with Gravitation Class 11, it is crucial to understand that gravity and gravitation are not similar. (a) walking on ground would became more difficult. Practice Now. 14. 8.2). Answer: (a) decreases If the interior contained matter which is not of the same density everywhere, then on the surface of the earth, the acceleration due to gravity. Answer: (a) A polar satellite goes around the earth’s pole in north-south direction. What is the angle between the equatorial plane and the orbital plane of. (b) The energy required to launch an orbiting satellite out of Earth’s gravitational influence is more/less than the energy required to project a stationary object at the same height (as the satellite) out of Earth’s influence. Molecules in air in the atmosphere are attracted by gravitational force of the earth. (b) Acceleration due to gravity increases with increasing depth (assume the earth to be a sphere of uniform density). Set 1 Register online for Physics tuition on Vedantu.com to score more marks in your Examination. At distance r from centre of earth, kinetic energy becomes zero (b) Angular speed also varies slightly. This solution is the result of referring to a number of textbooks by experts. MCQ Questions for Class 9 Science: Ch 10 Gravitation. The notes contain solution of all the numerical given in the chapter. Let the body have mass m. Question 8. Is it possibe for a body to have inertia but no weight? In order that a body of 5 kg weighs zero at the equator, the angular speed of the earth is (a) 1/80 rad /s (b) 1/400 rad /s (c) 1/800 rad /s (d) 1/1600 rad /s. Answer: Here G = 6.67 x 10-11 Nm2 kg-2; M = 100 kg; R = 0.1 m, distance between the two spheres, d = 1.0 m Shown are several curves (Fig. In our solar system, the inter-planetary region has chunks of matter (much smaller in size compared to planets) called asteroids. 8.3). (a) Calculate height of such a satellite. We know that. :. Answer: Question 8. Satellites orbiting the earth have finite life and sometimes debris of satellites fall to the earth. (b) In the conditions of weightlessness, the face of the astronaut is expected to get more supply. Question 8. How is the gravitational force between two point masses affected when they are dipped in water keeping the separation between them the same? Gravitation is one of the four classes of interactions found in nature. Question 8. What is the gravitational force on it due to the Earth at a height equal to half the radius of the Earth? CBSE papers with answers and solutions for chapter 8 Gravitation class 11th Physics includes practice question papers with 10-12 questions in each test paper. Here we have given NCERT Solutions for Class 11 Physics Chapter 8 Gravitation. Thus, we hope that through these class 11 Gravitation notes, you are now familiar with the basic concepts related to this topic. (b) none of the three laws of Kepler will be valid. Answer: Mass of Sun, M = 2 x 1030 kg; Mass of Earth, m = 6 x 1024 kg Distance between Sim and Earth, r = 1.5 x 1011 m (Take the potential energy at infinity to be zero). Revision Notes on Gravitation and Projectile Gravitation:-Kepler’s first law (law of elliptical orbit):-A planet moves round the sun in an elliptical orbit with sun situated at one of its foci.Kepler’s second law (law of areal velocities):-A planet moves round the sun in such a way that its areal velocity is constant. Question 8. The outward centrifugal force acting on a body of mass m at the equator of the star =mv2/R =mR w2——-(ii) 22. If 20% of its initial energy is lost due to Martian atmospheric resistance, how far will the rocket go from the surface of mars before returning to it? = 6400 + 36000 = 42400 km = 4.24 x 107 m. Question 8. CBSE Question Papers 11th Physics Chapter 8. Show the nature of the following graph for a satellite orbiting the earth. We also have the frames of reference in space. (d) The formula – GMm (1/r2-1/r1) is more/less accurate than the formula mg (r2 – r1) for the difference of potential energy between two points r2 and r1 distance away from the centre of the Earth. Question 8. Assume the stars to remain undistorted until they collide. Explain why all of them do not fall into the earth just like an apple falling from a tree. Suppose that the distance of either sphere from the mid-point of the line joining their centre is r. Then r=d/2=0.5 m. The gravitational field at the mid-point due to two spheres will be equal and opposite. Soln: g at the surface of earth = 9.8m/sec 2 (i) h = $\frac{{\rm{R}}}{2}$ g' = ? 15. What is the gain in its potential energy? Here we have given NCERT Solutions for Class 11 Physics Chapter 8 Gravitation. (a) Inertial mass is a measure of difficulty of accelerating a body by an external force whereas the gravitational mass is relevant in determining the gravitational force on it by an external mass. Answer: Here, mass of each star, M = 2 x  1030 kg Class 9 Physics Notes - Chapter 5 - Gravitation - Numerical Problems. 17. 18. As observed from earth, the sun appears to move in an approximate circular orbit. Hence, orientational problem will affect the astronaut in space. Choose the correct alternative: A star 2.5 times the mass of the sun and collapsed to a size of 12 km rotates with a speed of 1.2 rev. Define the following terms. Question 8. Take the diameter of the Milky way to be 105 ly. So, the astronaut will not get swollen feet. Question 8. Question 1. Give reason for your answer. Answer: Distance of satellite from the centre of earth = R = r + x These important questions of gravitation will play significant role in clearing concepts of Physics class 11 as well as in revision of 12th students. causing rotation around an axis through the c.m. Mass of the sun = 2 x 1030 kg, mass of the earth = 6 x 1024 kg. Free PDF download of Important Questions with solutions for CBSE Class 11 Physics Chapter 8 - Gravitation prepared by expert Physics teachers from latest edition of CBSE(NCERT) books. So, gravitational intensity, which is negative of gravitational potential gradient, is zero. (d) The escape speed of a body depends upon the height of the location from where the body is projected, because the escape velocity depends upon the gravitational potential at the point from which it is projected and this potential depends upon height also. Answer: Question 8. 6.67x 1011. c. … (d) for n negative, an object lighter than water will sink in water. Answer: At all points inside a hollow spherical shell, potential is same. Two identical heavy spheres are separated by a distance 10 times their radius. The variation in g can also be detected. Here we have covered Important Questions on Gravitation for Class 11 Physics subject. Question 8. (b) we will become hotter after billions of years. Find eccentricity of the orbit. The radius of each star is  104 km. Mass of the Mars = 6.4 x 1023 kg, Radius of Mars = 3395 km. Physics Class 11 Important Questions are very helpful to score high marks in board exams. per second. This is because. If the interior contained matter […] (c) projectile motion of a stone thrown by hand on the surface of the earth will be approximately parabolic. Ignore the presence of the Sun and other planets. The centre of mass of an extended body on the surface of the earth and its centre of gravity. 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