Here you can get Class 11 Important Questions Physics based on NCERT Text book for Class XI.Physics Class 11 Important Questions are very helpful to score high marks in board exams. m is much-much smaller than M and at time t = 0, they are all at rest (Fig. (a) will be directed towards the centre but not the same everywhere. Question 1. (a) walking on ground would became more difficult. Important Points about Gravitation Force (i) Gravitational force is a central as well as conservative force. Mass of the spaceship = 1000 kg, Mass of the Sun = 2 x 1030 kg. In the following two exercises, choose the correct answer from among the given ones: The gravitational intensity at the centre of a hemispherical shell of uniform mass density has the direction indicated by the arrow (see Fig.) What is the angle between the equatorial plane and the orbital plane of. Thus, we hope that through these class 11 Gravitation notes, you are now familiar with the basic concepts related to this topic. What is the potential due to Earth’s gravity at the site of this satellite? We know that. If the mass is removed further away such that OP becomes 2h, by what factor the force of gravitation will decrease, if h = r ? Neglect any mass loss of the comet when it comes very close to the Sun. What is the speed of the body far away from the Earth? (b) Find out the minimum number of satellites that are needed to cover entire earth so that at least one satellites is visible from any point on the equator. Select the correct option to test your skills Gravitation. Answer:  Let R be the radius of orbit of Mars and R’ be the radius of the Mars. Is it possibe for a body to have inertia but no weight? If so, is the equilibrium stable or unstable? For the earth-sun system (approximating the earth as a uniform density sphere). Gravitation is important from the perspective of scoring high in IIT JEE, AIEEE and other engineering examination as the questions based on them are direct and do not have much twist and turns. = 6400 + 36000 = 42400 km = 4.24 x 107 m. Question 8. Neglect the effect of other planets etc. Certain stellar objects called pulsars belong to this category). 24. Before starting with Gravitation Class 11, it is crucial to understand that gravity and gravitation are not similar. Earth’s orbit is an ellipse with eccentricity 0.0167. (i) a, (ii) b, (iii) c, (iv) 0. If the gravitational field is supposed to be uniform, the work done in moving a 2 kg mass from the surface of the planet to a height of 8 m is (c) The escape speed does not depend on the direction of projection of a body. The centre of mass of an extended body on the surface of the earth and its centre of gravity. Answer: Acceleration due to gravity of the star,g= GM/R2 …………(i) (c) A geostationary satellite goes around the earth in west-east direction. Choose the correct alternative: The radius of each star is  104 km. 8.2). (a) the acceleration due to gravity on earth will be different for different objects. (b) will not be strictly elliptical because the total gravitational force on it is not central. 23. (d) thrust. QUESTIONS FROM TEXTBOOK. As observed from the sun, the orbit of the moon. A ball is projected vertically upwards with an initial velocity of u goes to a maximum height h before … 9.Which of the following symptoms is likely to afflict an astronaut in space (a) swollen feet, (b) swollen face, (c) headache, (d) orientational problem. This solution is the result of referring to a number of textbooks by experts. .•. Answer:  Initial kinetic energy of rocket = 1/2 mv2 = 1/2 x m x (5000)2 = 1.25 x 107 mJ Here we have covered Important Questions on Gravitation for Class 11 Physics subject.. Physics Important Questions Class 11 are given below.. Ignore the presence of the Sun and other planets. Practice Now. (d) will move in orbits like planets and obey Kepler’s laws. Answer: Question 8. (orbital radius = 1.5 x 1011 m). NCERT Solutions for Class 6, 7, 8, 9, 10, 11 and 12. The mean orbital radius of the earth around the sun is 1.5 x 108 km. A star like the sun has several bodies moving around it at different distances. Which of the following options are correct? (c) Comet has constant angular momentum. (a) planets will not have elliptic orbits. Since gain in K.E. 1. Total K.E. … of the stars = 1/2Mv2 + 1/2Mv2 How far from the earth does the rocket go before returning to the earth? Can we shield a body from the gravitational influence of nearby matter by putting it inside a hollow sphere or by some other means? (a) the solar cells and batteries in satellites run out. The earth is an approximate sphere. (mass of the sun = 2 x 1030 kg). Will an object placed at the mid point of the line joining their centres be in stable equilibrium or unstable equilibrium? From equation (i), the acceleration due to the gravity of the star (d) there will be no gravitational force inside a spherical shell of uniform density. (take, the mass of the Sun = 1.99 x 10^30 Kg. Question 8. A day should be taken from noon to noon. You are expected to do all the questions based on this to remain competitive in IIT JEE examination. A rocket is fired from the earth towards the sun. Is an object placed at that point in equilibrium ? Give reason for your answer. 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. NCERT Solutions Class 11 Physics Physics Sample Papers. (a) The escape speed of a body from the Earth does not depend on the mass of the body. A comet orbits the Sun in a highly elliptical orbit. Here we have given NCERT Solutions for Class 11 Physics Chapter 8 Gravitation. Why? You also get idea about the type of questions and method to answer in your Class 11th examination. 6.67x 1011. c. … 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. (c) If you compare the gravitational force on the Earth due to the Sun to that due to the Moon, you would find that the Sun’s pull is greater than the Moon’s pull. Contents. Give one example each of central force and non-central force. The gravitational force between a hollow spherical shell (of radius R and uniform density) and a point mass is F. Show the nature of F vs r graph where r is the distance of the point from the centre of the hollow spherical shell of uniform density. A satellite orbits the earth at a height of 400 km above the surface. So, gravitational intensity, which is negative of gravitational potential gradient, is zero. As you have learnt in the text, a geostationary satellite orbits the Earth at a height of nearly 36,000 km from the surface of the Earth. The value of G is independent of the nature and size of the bodies well as the nature of the medium between them. 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 Gravitation is one of the four classes of interactions found in nature. M = 2.5 x 1011 solar mass = 2.5 x 1011 x (2 x 1030) kg = 5.0 x 1041kg (e) Potential energy varies along the path. (a) Calculate height of such a satellite. Two identical heavy spheres are separated by a distance 10 times their radius. (c) Acceleration due to gravity increases with increasing latitude. If the space station orbiting around the Earth has a large size, can he hope to detect gravity? If the law of gravitation, instead of being inverse-square law, becomes an inverse-cube law-. (b) none of the three laws of Kepler will be valid. Molecules in air in the atmosphere are attracted by gravitational force of the earth. 17. A spaceship is stationed on Mars. SI Unit of pressure is (a) Pascal (b) Newton (c) Dyne (d) barye Answer. The radius of the earth is 6400 km and g = 10 m/s². An astronaut inside a small spaceship orbiting around the earth cannot detect gravity. (c) mass of the body The notes contain solution of all the numerical given in the chapter. (f) Total energy throughout the orbit remains constant. 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