Have you ever questioned why things never fail to fall on the ground or why some things float on water, yet others sink? Class 9 science chapter 10: Gravitation, makes you study these wonderful concepts. This chapter describes the mechanism of gravity and the distinction between mass and weight, as well as such concepts as free fall and buoyancy in a simple manner.
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To ensure that you understand these topics effectively, the NCERT Exemplar Solutions offers clear and reliable answers depending on the most recent CBSE syllabus. The answers to the 15 multiple-choice questions (MCQs), 7 short-answer questions, and 4 long-answer questions in the NCERT Exemplar Class 9 Science Solutions Chapter 10 Gravitation are well explained. Taking these questions regularly enhances your problem-solving abilities, makes you get the concepts well and also be familiar with the exam-type questions. These are also the best examples in NCERT Exemplar Class 9 Solutions Science Chapter 10 Gravitation that can be revised after a very short period of time before your examinations, and are also very helpful in securing good grades in your Class 9 science exams.
Chapter 10 Gravitation Multiple Choice Questions (MCQs) assist students in assessing their knowledge of concepts such as gravity, free fall, mass, weight, pressure, and buoyancy. The conceptual clarity and confidence in CBSE Class 9 Science tests are gained through practising these MCQs.
Question:1
Two objects of different masses falling freely near the surface of moon would
(a) have same velocities at any instant
(b) have different accelerations
(c) experience forces of the same magnitude
(d) undergo a change in their inertia
Answer: A
When a body is dropped near the surface of the Moon, it would be attracted by the Moon’s gravitational force.Question:2
The value of acceleration due to gravity
(a) is same on equator and poles
(b) is least on poles
(c) is least on the equator
(d) increases from pole to equator
Answer:
Ans. CQuestion:3
The gravitational force between two objects is F. If masses of both objects are halved without changing distance between them, then the gravitational force would become
(a) $\frac{F}{4}$
(b) $\frac{F}{2}$
(c) F
(d) 2 F
Answer:
Ans. AQuestion:4
A boy is whirling a stone tied with a string in a horizontal circular path. If the string breaks, the stone
(a) will continue to move in the circular path
(b) will move along a straight line towards the centre of the circular path
(c) will move along a straight line tangential to the circular path
(d) will move along a straight line perpendicular to the circular path away from the boy
Answer:
Ans. CQuestion:5
An object is put one by one in three liquids having different densities. The object floats with 1/9, 2/11 and 3/7 parts of their volumes outside the liquid surface in liquids of densities d1, d2 and d3 respectively. Which of the following statement is correct?
(a) d1 > d2 > d3
(b) d1 > d2 < d3
(c) d1< d2 > d3
(d) d1< d2 < d3
Answer:
Ans. DQuestion:6
In the relation $F= \frac{GmM}{d^{2}}$, the quantity G
(a) depends on the value of g at the place of observation
(b) is used only when the earth is one of the two masses
(c) is greatest at the surface of the earth
(d) is universal constant of nature
Answer:
DQuestion:7
Law of gravitation gives the gravitational force between
(a) the earth and a point mass only
(b) the earth and Sun only
(c) any two bodies having some mass
(d) two charged bodies only
Answer:
CQuestion:8
The value of quantity G in the law of gravitation
(a) depends on mass of earth only
(b) depends on radius of earth only
(c) depends on both mass and radius of the earth
(d) is independent of mass and radius of the earth
Answer:
D Gravitational force is a fundamental force, and it comes because of the property of mass.Question:9
Two particles are placed at some distance. If the mass of each of the two particles is doubled, keeping the distance between them unchanged, the value of gravitational force between them will be
(a) $\frac{1}{4}$times (b) 4 times (c) $\frac{1}{2}$ times (d) unchanged
Answer:
BQuestion:10
The atmosphere is held to the earth by
(a) gravity
(b) wind
(c) clouds
(d) earth’s magnetic field
Answer:
AQuestion:11
The force of attraction between two unit point masses separated by a unit distance is called
(a) gravitational potential
(b) acceleration due to gravity
(c) gravitational field
(d) universal gravitational constant
Answer: D
By the universal law of gravitation, if two particles of mass m1 and m2 are kept at a separation, then the gravitational force between them will be given as:Question:12
The weight of an object at the centre of the earth of radius R is
(a) zero
(b) infinite
(c) R times the weight at the surface of the Earth
(d) $\frac{1}{R^{2}}$ times the weight at surface of the earth
Answer: A
When we go towards the centre of the Earth from the surface, the acceleration due to gravity decreases.Question:13
An object weighs 10 N in air. When immersed fully in water, it weighs only 8 N. The weight of the liquid displaced by the object will be
(a) 2 N (b) 8 N (c) 10 N (d) 12 N
Answer: A
The weight of an object decreases when it is immersed in any fluid. This decrease in weight is caused due to buoyancy.Question:14
A girl stands on a box having 60 cm length, 40 cm breadth and 20 cm width in three ways. In which of the following cases, pressure exerted by the brick will be
(a) maximum when length and breadth form the base
(b) maximum when breadth and width form the base
(c) maximum when width and length form the base
(d) the same in all the above three cases
Answer: B
The pressure is defined as the normal force per unit area.Question:15
An apple falls from a tree because of gravitational attraction between the earth and apple. If F1 is the magnitude of force exerted by the earth on the apple and F2 is the magnitude of force exerted by apple on earth, then
(a) F1 is very much greater than F2
(b) F2 is very much greater than F1
(c) F1 is only a little greater than F2
(d) F1 and F2 are equal
Answer: D
Newton’s third law states that every action has an equal and opposite reaction.The NCERT Exemplar Chapter 10 Gravitation short-answer type questions aid the students to elaborate in concise but meaningful sentences. These questions enhance the power of logical thinking and the insight into the issues of buoyancy, the gravitational force, and free fall. Answering them frequently enhances performance in examinations.
Question:16
Answer:
When any particle performs circular motion, the centripetal force is required to change the direction of the velocity.Question:17
Answer:
The motion in the vertical direction will not be affected by horizontal motion.Question:18
Answer:
The moon revolves around the Earth.Question:19
Answer:
The value of gravity near the equator is less than the value of gravity near the pole.Question:20
Answer:
It is given that the weight of any person on the moon is about 1/6th that on Earth.Question:21
Calculate the average density of the earth in terms of g, G and R.
Answer:
The weight of an object is nothing but the gravitational force of the Earth on that body.Question:22
The earth is acted upon by gravitation of Sun, even though it does not fall into the Sun. Why?
Answer:
The Earth is acted upon by the gravitation force of the Sun; this gravitational force provides the needed centripetal force to the Earth.These long-answer questions in Chapter 10, Gravitation, provide more detailed explanations, derivations and real-life examples. By practising them, you will strengthen your conceptual knowledge and improve the skills of answering descriptive questions in the final exam.
Question:23
Answer:
The weight of an object is nothing but the gravitational force of Earth on that body.Question:24
Answer:
By the universal law of gravitation, we know that the force between two particles kept at a fixed separation will be proportional to the product of their masses.Question:25
Answer:
The weight of an object is nothing but the gravitational force of Earth on that body.Question:26
(a) A cube of side 5 cm is immersed in water and then in saturated salt solution. In which case will it experience a greater buoyant force? If each side of the cube is reduced to 4 cm and then immersed in water, what will be the effect on the buoyant force experienced by the cube as compared to the first case for water? Give reason for each case.
(b) A ball weighing 4 kg of density 4000 kgm-3 is completely immersed in water of density 1000 kgm-3 .Find the force of buoyancy on it.
Answer:
(a) Force of buoyancy in any liquid is equal to the weight of displaced fluid.$\begin{gathered}
M=d \times V \\
V=\frac{M}{d}=\frac{4}{4000} m^3
\end{gathered}$
Now, we know the displaced volume, we can calculate the force of buoyancy.
$\begin{aligned}
& F_b=d V g \\
& \text { where } V=\frac{4}{4000} m^3 \\
& \Rightarrow F_b=1000 \times \frac{4}{4000} \times 10=10 \mathrm{~N}
\end{aligned}$
The chapter Gravitation assists the student to learn about the way objects attract one another because of the force of gravity and the reason why everything falls down on the Earth. Mass, weight, free fall, buoyancy, and the universal law of gravitation are some of the main concepts taught to students in this topic. The numerical questions will require one to comprehend and memorise the formulas and concepts well. These are the main key concepts which are the foundation for higher classes and competitive exams.
1. Universal Law of Gravitation
$
F=\frac{G m_1 m_2}{r^2}
$
where
$F=$ gravitational force
$G=$ universal gravitational constant $\left(6.67 \times 10^{-11} \mathrm{Nm}^2 / \mathrm{kg}^2\right)$
$m_1, m_2=$ masses of objects
$r=$ distance between centers of the two objects
2. Acceleration Due to Gravity (g)
$
g=\frac{G M}{R^2}
$
where
$M=$ mass of Earth
$R=$ radius of Earth
3. Relation Between Mass and Weight
$
W=m g
$
4. Free Fall
$
v=u+g t
$
$
s=u t+\frac{1}{2} g t^2
$
5. Equation for Density
$
\text { Density }=\frac{\text { Mass }}{\text { Volume }}=\frac{m}{V}
$
6. Buoyant Force
7. Archimedes’ Principle
8. Pressure in Fluids
$
P=h \rho g
$
where
$h=$ depth
$\rho=$ density of liquid
$g$ = acceleration due to gravity
The NCERT Exemplar Solutions Class 9 Chapter 10 Gravitation provides the students with a clear explanation of complex concepts such as the gravitational force, buoyancy and the phenomenon of the free fall. These solutions enhance the conceptual knowledge and problem-solving ability. They are also used to aid the students to familiarise themselves with the pattern of examination, as well as enhancing confidence in board and school-level examinations.
NCERT Class 9 Science Exemplar Solutions for other chapters provide well-structured, high-quality practice material designed to strengthen conceptual understanding and analytical skills. These solutions assist students in solving application-based and higher-level questions that usually emerge in competitive and school examinations. They simplify the complex topics by providing straightforward explanations and logical ways of learning, thus making it easier to revise.
|
Chapter-wise solutions |
Also, read - NCERT Solutions for Class 9
| Chapter No. | Chapter Name |
| Chapter 1 | Matter in Our Surroundings |
| Chapter 2 | Is Matter Around Us Pure |
| Chapter 3 | Atoms and Molecules |
| Chapter 4 | Structure of The Atom |
| Chapter 5 | The Fundamental Unit of Life |
| Chapter 6 | Tissues |
| Chapter 7 | Motion |
| Chapter 8 | Force and Laws of Motion |
| Chapter 9 | Gravitation |
| Chapter 10 | Work and Energy |
| Chapter 11 | Sound |
| Chapter 12 | Improvement in Food Resources |
Frequently Asked Questions (FAQs)
You can get detailed and step-by-step Gravitation Class 9 NCERT Exemplar Solutions from Careers360 NCERT Exemplar Class 9 Science Solutions Chapter 10 Gravitation PAGE. These solutions include MCQs, short answers, long answers, and numericals explained as per the CBSE syllabus.
The Class 9 Science Exemplar Chapter 10 Gravitation includes multiple-choice questions (MCQs), short answer questions, long answer questions, and numerical problems to help students practice different types of questions asked in exams.
It states that every object in the universe attracts every other object with a force directly proportional to their masses and inversely proportional to the square of the distance between them.
Due to Earth’s gravitational pull acting on them.
Practising Gravitation Class 9 Extra Questions and Numericals helps you understand key topics like universal law of gravitation, free fall, and buoyancy better. It also improves your problem-solving skills for school exams and competitive tests.
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