Class-9CBSE Board - Universal Law of Gravitation - LearnNext offers animated video lessons with neatly explained examples, Study Material, FREE NCERT Solutions, Exercises and Tests. (c) Reeta’s friend showed the value of being helpful, concerned and intelligent. Answer: Why is it difficult to hold a school bag having a strap made of a thin and strong string? Why is it difficult to hold a school bag having a strap made of a thin and strong string? (a) the elongation of the string is 6 cm. Why is the wall of dam reservoir thicker at the bottom? But if downward force is greater than upward force, the bottle will sink. Here you can read Chapter 10 of Class 9 Science NCERT Book. Note the elongation of the string or the reading on the spring balance due to the weight of the stone. Camels can walk easily on desert sand but we are not comfortable walking on the sand. At TopperLearning, CBSE Class 9 Physics NCERT textbook solutions are available 24/7 along with other learning materials. A sheet of paper has more surface area than a crumpled ball of paper. Answer: The force exerted by a thin and strong string is distributed to very less area and hence the force applied due to the bag is more, the pressure exerted on the body by thin straps will be more and hence will be more painful. Now, we have to find the pressure exerted by the wooden block on the table top by keeping it vertically and horizontally. The length of the string in case (b) decreases due to the upward force exerted by water on the stone called as buoyant force. Hence, Amit's friend will not agree with the weight of the gold bought. The mass of an object is the measure of its (a) pressure. Answer: The force exerted when acts on a smaller area, it exerts larger pressure. Question 5. This force is called buoyant force or upthrust and the property due to which a fluid exerts this upthrust on an object placed in it, is called buoyancy. If R is the radius of the Earth, then according to the universal law of gravitation, the gravitational force (F) acting between the Earth and the object is given by the relation: Gravity of the Earth attracts every object towards its centre. State the universal law of gravitation and its mathematical form. (b) 60 kg. What does this mean? (d) thrust. Maximum height reached by the stone, h = ? Hence, the ball was thrown upwards with a velocity of 29.4 ms -1. Mass of an object is a constant quantity. Question 7. Concept Insight  Weight is a force but mass is not. What are fluids? CBSE Notes Class 9 Science Gravitation . According to the universal law of gravitation, gravitational force between two objects of masses M and m at a distance r from each other is given by: Let mass of the object be represented by m = 1 kg, Universal gravitational constant, G = 6.7 × 10-11 Nm2 kg-2, Since the object is on the surface of the Earth, r = radius of the Earth (R). Why does an object float or sink when placed on the surface of water? Mass of both cotton bag and iron bag is same. By using the NCERT Solutions for Class 9 Science Gravitation, a student can save time in finding the right answers. Mass is the quantity of matter contained in a body. (c) What value of Tarun is reflected in this case? The area is reduced and the pressure exerted is more. Acceleration due to gravity on earth, ge = 9.8 m/s2, Therefore, weight of a 10 kg object on the Earth = 10 × 9.8 = 98 N, Therefore, weight of the same object on the Moon =, Concept Insight Weight of an object on Moon =   of the weight of the object on Earth. We will also introduce a mobile app for viewing all the notes on mobile. What is the S.I. Why a truck or a motorbike has much wider tyres? Let RE be the radius of the Earth. Concept Insight Choose the equation of motion wisely to minimize the number of steps in calculations. In Fig. This will clear students doubts about any question and improve application skills while preparing for board exams. (b) when the stone is dipped in water the length of string reduced to 5 cm. Answer: The pressure exerted by it can be distributed to more area, and avoid the wear and tear of tyres. Can you say which one is heavier and why? opposite to the direction of the force exerted by the object. What is lactometer and hydrometer? If you are a student of class 9 who is using NCERT Textbook to study Science, then you must come across Chapter 10 Gravitation. Get Gravitation, Physics Chapter Notes, Questions & Answers, Video Lessons, Practice Test and more for CBSE Class 10 at TopperLearning. Copyright Notice © 2020 Greycells18 Media Limited and its licensors. ... Class 9 NCERT Solutions. The relative density of silver is 10.8. When objects fall towards the Earth under the effect of gravitational force alone, then they are said to be in free fall. So it floats on water. Three balls were given and few disposable glasses were kept. If the density of an object is less than the density of water then the object will float. You find your mass to be 42 kg on a weighing machine. 3. Verify your number to create your account, Sign up with different email address/mobile number, NEWSLETTER : Get latest updates in your inbox, Need assistance? The upward force (buoyant force) acting on the bottle can be reduced by increasing the force on the bottle or by filling the bottle with sand, water etc. Question 8. NCERT Solutions Class 9 Science Chapter 10 Gravitation – Here are all the NCERT solutions for Class 9 Science Chapter 10. This is because of the reason that. In the Physics Part 1 Board has issued 19 MCQs that is necessary to pass to every student. In this page find links for free mcq questions for class 9 science. (c) What value of milkman is seen in this case? T. Question 5. he relative density of gold is 19.3. It is difficult to hold a school bag having a thin strap because the pressure exerted on the shoulders is quite large. This is because the buoyant force acting on the object is greater than the force of gravity acting on it. Question 6. The mass of the body on the moon will be (a) 6 kg. Free PDF download of Important Questions with solutions for CBSE Class 9 Science Chapter 10 - Gravitation prepared by expert Science teachers from latest edition of CBSE(NCERT) books. Answer: Consider a block of wood kept on a table top. 3. Answer: The upward force exerted by any fluid (liquid, gas) on an object is known as upthrust or buoyancy. As pressure is inversely proportional to area, if the area is reduced pressure. Question 22. You can find 1. mcq for class 9 biology 2. mcq for class 9 chemistry and 3. mcq for class 9 physics Just click on any one of the online mcq test for class 9 cbse science. Free CBSE Online Test for . All these topics are included in CBSE solved test papers of class 10 Science chapter Gravitation. Hence, it accelerates at a rate much lesser than the acceleration rate of the Moon towards the Earth. This is because the buoyant force acting on the object is less than the force of gravity acting on it. Gravitation Class 9 Extra Questions HOTS (Higher Order Thinking Skills) Question 1. 1. Two cork pieces of same size and mass are dipped in two beakers containing water and oil. unit of thrust? Observe what happens to the elongation of the string or the reading on the balance. → The stone is when accelerated towards earth, means some force is acting on it. Online MCQ test for class 9 CBSE science When an object is released from a height such that it falls towards the surface of the Earth under the influence of gravitational force alone, the motion of the object is called free fall. Similarly, if the distance is tripled, then the gravitational force becomes one-ninth of its original value. The floating or sinking of a body in the water is decided by the density of both the body and water’s buoyant force acting on the body by the liquid. (ii) Let t be the time taken by the ball to reach the height 122.5 m, then to calculate t we use the following equation of motion: Therefore, the total time taken by the ball to return = 5 + 5 = 10 s, Hence, the velocity of the stone just before touching the ground is 19.6 ms, R = Average distance between the Earth and the Sun = 1.5 × 10, G = Universal gravitational constant = 6.7 × 10. Gravitation NCERT In Text Solution. It is true that gravitational force acts on all objects in proportion to their masses. If the masses of both the objects are doubled, then the gravitational force becomes four times the original value. In what direction does the buoyant force on an object immersed in a liquid act? Now, slowly dip the stone in the water in a container as shown in Fig. Revise the difference between weight and mass. Hence, the ball was thrown upwards with a velocity of 29.4 ms, Initial velocity during the upward journey, u = 29.4 ms, Acceleration due to gravity, g = -9.8 m s. (c) Ball attains the maximum height after 3 s. After attaining this height, it will start falling downwards. The cost floats as the density of cost is less and the buoyant force exerted on it is more than the downward force. If the distance is doubled, then the gravitational force becomes one-fourth of its original value. The Earth attracts the Moon with a force which is same as the force with which the moon attracts the Earth because according to Newton's third law of motion, force of action and reaction are always equal and opposite. A body of mass 1kg is attracted by the earth with a force which is equal to. b. The ball takes a total of 6 s for its upward and downward journey. Instutor and our team help you to get out from this Situation. Contact us on below numbers. Answer: The force exerted per unit area is called pressure. To download Gravitation class 9 Notes, sample paper for class 9 Mathematics, Social Science, Science, English Communicative; do check myCBSEguide app or website. Answer: It means that the density of silver is 10.8 times more than that of water. So the nails have pointed tips. (b) Let the maximum height attained by the ball be h. Initial velocity during the upward journey, u = 29.4 ms -1, Acceleration due to gravity, g = -9.8 m s -2. (b) Name the principle used here. Gravitation, CBSE Science Class 9 NCERT Solutions. (c) … An apple falls from a tree because of the gravitational attraction between the earth and the apple. Why is Archimedes’ principle applicable only for fluids? The gravitational force acting between two objects is directly proportional to the product of their masses and inversely proportional to the square of the distance between their centres. ) … a body ball of paper and hence it falls slower the! 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