NCERT Solutions for class 11 Physics Chapter 8: Gravitation

NCERT Solutions for Class 11 Physics Chapter 8: Gravitation covers concepts of Kepler’s Planetary Laws of Motion, Newton’s Law of Gravitation, Acceleration Due to Gravity, and its variation. Gravity, also known as Gravitational Force, is the universal force of attraction that helps to keep things together.

Class 11 Physics Chapter 8 Gravitation along with Unit 4 Work, Energy, and Power and Unit 5 Motion of System of Particles and Rigid Body has a weightage of 17 marks in the Class 11 Physics Examination. Gravity is the force that holds us onto the Earth and does not let us fly up into space. Although we barely think about it in our daily lives Gravity is essential to keep the systems operating on the Earth and the Universe.

Download PDF: NCERT Solutions for Class 11 Physics Gravitation

NCERT Solutions for Class 11 Physics Chapter 8

Class 11 Physics Chapter 8 – Basic Concepts

Kepler’s Laws of Planetary Motion: Kepler formulated three laws to describe planetary motion – Law of Orbits, Law of areas, and Law of periods.

1. Law of orbits: All the planets revolve around the sun in an elliptical orbit with the sun being at one of the foci of the ellipse.
2. Law of areas: The speed of a planet varies such that its radius, the vector drawn from the sun to the planet sweeps out equal areas in equal intervals of times.
3. Law of Periods: The square of the time period of revolution of a planet is proportional to the cube of the semi-major axis of the elliptical orbit. $T^2 \propto r^3$

Newton’s law of gravitation states that each particle in the universe attracts another particle with a force that is directly proportional to the product of their masses. It is also inversely proportional to the square of the distance that exists between them.

$F_g = {Gm_1m_2 \over r^2}$

The gravitational potential is the amount of work done in bringing a body with unit mass from infinity to a point in the gravitational field of a body.

V = $-GM \over R$

Escape Velocity is the minimum velocity that is required to project a body vertically upward from the surface of the Earth so that it comes out of its gravitational field.

$v_{escape} = \sqrt{2GM \over R}$

Orbital velocity is the minimum velocity required to put a satellite into a given orbit around the Earth.

$v_{orbital} = \sqrt{GM \over R}$

Class 11 Physics Chapter 8 Related Guides:

Gravitational Potential Energy	Escape Speed	Earth satellites
Weightlessness	Neptune	Specific Gravity
Value of gravitational constant	Motion of celestial bodies in space	Value of g on moon
Relation between G and g	Specific gravity formula	Universal gravitation formula

Class 11 Physics Study Guides:

NCERT Solutions for Class 11 Physics	Physics Formula	Physics Study Notes
Difference between in Physics	Class 11 Physics Notes	Derivations in Physics
SI Units in Physics	Physics Constants	Relation between articles in Physics

CBSE CLASS XII Related Questions

1.
The number of free electrons per unit volume ($\text{m}^3$) in a wire made of copper (resistivity $1.72 \times 10^{-8}\,\Omega\,\text{m}$) is $8.5 \times 10^{28}$. Calculate the average number of collisions made by an electron in one second when an electric field is maintained in the wire.
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2.
A parallel beam of monochromatic light falls normally on a single slit of width $a$ and a diffraction pattern is observed on a screen placed at distance $D$ from the slit. Explain:
(I) the formation of maxima and minima in the diffraction pattern, and
(II) why the maxima go on becoming weaker and weaker with its increasing number $n$.
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3.
(I) The real image of an object placed between $f$ and $2f$ from a convex lens can be seen on a screen placed at the image location. If the screen is removed, is the image still there? Explain.
(II) Plane and convex mirrors produce virtual images of objects. Can they produce real images under some circumstances? Explain.
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4.
Find the ratio $\dfrac{\lambda_\alpha}{\lambda_p}$ of the de Broglie wavelength $\lambda_\alpha$ associated with an alpha particle to the de Broglie wavelength $\lambda_p$ associated with a proton if both are moving with the same velocity.
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5.
Draw the plot of potential energy of a pair of nucleons as a function of their separation. Write two important conclusions that can be drawn from this plot.
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6.
A square loop of side 0.50 m is placed in a uniform magnetic field of 0.4 T perpendicular to the plane of the loop. The loop is rotated through an angle of $60^\circ$ in 0.2 s. The value of emf induced in the loop will be:
- 5 V
- 3.5 V
- 2.5 V
- Zero V
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