NCERT Solutions For Class 11 Physics Chapter 7: System of Particles and Rotational Motion

NCERT Solutions for Class 11 Physics Chapter 7 System of Particles and Rotational Motion covers all the concepts discussed in the Class 11 Physics Chapter 7. The combination of rotational motion and the translational motion of a rigid body is known as rolling motion. According to the law of conservation of angular momentum, if there is no external couple acting, the total angular momentum of a rigid body or a system of particles is conserved.

Class 11 Physics Chapter 7 System of Particles and Rotational Motion has a weightage of 17 marks along with Unit 4 Work, Energy, and Power and Unit 6 Gravitation. The Class 11 Physics Chapter 7 discusses the concepts of Torque, Angular Momentum, and Rotational Kinetic Energy.

Download PDF: NCERT Solutions for Class 11 Physics Chapter 7

NCERT Solutions for Class 11 Physics Chapter 7

Class 11 Physics Chapter 7 – Concepts Covered

Centre of Mass: For a system of particles, the centre of mass is the balancing point where the entire mass of the system is concentrated, for consideration of its translational motion.

If there are 2 particles with mass m1 and m2 with position vectors \(\overrightarrow{r_1}\ and\ \overrightarrow{r_2}\), then the position vector of centre of mass is given as:

\(\overrightarrow{r_{cm}} = {{m_1}\overrightarrow{r_{1}} + {m_2}\overrightarrow{r_{2}} \over m_1 + m_2}\)

The cross product of two vectors \(\overrightarrow{A}\) and \(\overrightarrow{B}\) is another vector \(\overrightarrow{C}\), which has a magnitude equal to the product of the magnitudes of 2 vectors and the sine of the smaller angle \(\theta\) between them.

\(\overrightarrow{A} \times \overrightarrow{B} = \overrightarrow{C} = ABsin\theta \hat{c}\)

Torque or moment of force is the product of the magnitude of the force acting on a particle and the perpendicular distance of the application of this force from the axis of rotation of the particle.

\(Torque = Force \times perpendicular\ distance\)

The angular momentum about an axis of rotation is a vector quantity, with a magnitude equal to the product of the magnitude of momentum and the perpendicular distance of the line of action of momentum from the axis of rotation. Its direction is perpendicular to the plane that contains the momentum and the perpendicular distance.

\(\overrightarrow{L} = \overrightarrow{r} \times \overrightarrow{p} \)

Torque and angular momentum are correlated to each other.

\(\tau = {\overrightarrow{dL} \over dt}\)

Class 11 Physics Chapter 7 Related Guides:

Unit of Moment of Inertia	Angular Speed	Radial Acceleration
Relation Between Torque and Moment of Inertia	Angular Speed Formula	Angular Acceleration
Moment of Inertia	Rolling Motion	Unit of Moment of Inertia
Angular displacement	Angular speed	Radial Acceleration
Radius of Gyration	Rigid Bodies	Tangential Velocity Formula

Class 11 Physics Study Guides:

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

CBSE CLASS XII Related Questions

1.
A circular coil of 100 turns and radius \( \left(\frac{10}{\sqrt{\pi}}\right) \, \text{cm}\) carrying current of \( 5.0 \, \text{A} \) is suspended vertically in a uniform horizontal magnetic field of \( 2.0 \, \text{T} \). The field makes an angle \( 30^\circ \) with the normal to the coil. Calculate:
the magnetic dipole moment of the coil, and
the magnitude of the counter torque that must be applied to prevent the coil from turning.

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2.
Determine the current in the \( 3 \, \Omega \) branch of a Wheatstone Bridge in the circuit shown in the figure.

View Solution

3.
If Bohr’s quantization postulate (angular momentum \( = \frac{nh}{2\pi} \)) is a basic law of nature, it should be equally valid for the case of planetary motion also. Why, then, do we never speak of quantization of orbits of planets around the Sun? Explain.

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4.
In a Young's double-slit experiment, two waves each of intensity I superpose each other and produce an interference pattern. Prove that the resultant intensities at maxima and minima are 4I and zero respectively.

View Solution

5.
A 500 nm photon is incident normally on a perfectly reflecting surface and is reflected. The value of momentum transferred to the surface is:

\( 3.87 \times 10^{-43} \, \text{kg} \, \text{ms}^{-1} \)
\( 2.5 \times 10^{-30} \, \text{kg} \, \text{ms}^{-1} \)
\( 2.65 \times 10^{-27} \, \text{kg} \, \text{ms}^{-1} \)
\( 1.33 \times 10^{-27} \, \text{kg} \, \text{ms}^{-1} \)

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6.
Two small identical metallic balls having charges \( q \) and \( -2q \) are kept far at a separation \( r \). They are brought in contact and then separated at distance \( \frac{r}{2} \). Compared to the initial force \( F \), they will now:

attract with a force \( \frac{F}{2} \)
repel with a force \( \frac{F}{2} \)
repel with a force \( F \)
attract with a force \( F \)

View Solution

NCERT Solutions For Class 11 Physics Chapter 7: System of Particles and Rotational Motion

NCERT Solutions for Class 11 Physics Chapter 7

Class 11 Physics Chapter 7 – Concepts Covered

CBSE CLASS XII Related Questions

2.
Determine the current in the \( 3 \, \Omega \) branch of a Wheatstone Bridge in the circuit shown in the figure.

3.
If Bohr’s quantization postulate (angular momentum \( = \frac{nh}{2\pi} \)) is a basic law of nature, it should be equally valid for the case of planetary motion also. Why, then, do we never speak of quantization of orbits of planets around the Sun? Explain.

4.
In a Young's double-slit experiment, two waves each of intensity I superpose each other and produce an interference pattern. Prove that the resultant intensities at maxima and minima are 4I and zero respectively.

5.
A 500 nm photon is incident normally on a perfectly reflecting surface and is reflected. The value of momentum transferred to the surface is:

6.
Two small identical metallic balls having charges \( q \) and \( -2q \) are kept far at a separation \( r \). They are brought in contact and then separated at distance \( \frac{r}{2} \). Compared to the initial force \( F \), they will now:

Similar Physics Concepts

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NCERT Solutions For Class 11 Physics Chapter 7: System of Particles and Rotational Motion

NCERT Solutions for Class 11 Physics Chapter 7

Class 11 Physics Chapter 7 – Concepts Covered

CBSE CLASS XII Related Questions

2. Determine the current in the \( 3 \, \Omega \) branch of a Wheatstone Bridge in the circuit shown in the figure.

3. If Bohr’s quantization postulate (angular momentum \( = \frac{nh}{2\pi} \)) is a basic law of nature, it should be equally valid for the case of planetary motion also. Why, then, do we never speak of quantization of orbits of planets around the Sun? Explain.

4.In a Young's double-slit experiment, two waves each of intensity I superpose each other and produce an interference pattern. Prove that the resultant intensities at maxima and minima are 4I and zero respectively.

5.A 500 nm photon is incident normally on a perfectly reflecting surface and is reflected. The value of momentum transferred to the surface is:

6.Two small identical metallic balls having charges \( q \) and \( -2q \) are kept far at a separation \( r \). They are brought in contact and then separated at distance \( \frac{r}{2} \). Compared to the initial force \( F \), they will now:

Similar Physics Concepts

Comments

SUBSCRIBE TO OUR NEWS LETTER

2.
Determine the current in the \( 3 \, \Omega \) branch of a Wheatstone Bridge in the circuit shown in the figure.

3.
If Bohr’s quantization postulate (angular momentum \( = \frac{nh}{2\pi} \)) is a basic law of nature, it should be equally valid for the case of planetary motion also. Why, then, do we never speak of quantization of orbits of planets around the Sun? Explain.

4.
In a Young's double-slit experiment, two waves each of intensity I superpose each other and produce an interference pattern. Prove that the resultant intensities at maxima and minima are 4I and zero respectively.

5.
A 500 nm photon is incident normally on a perfectly reflecting surface and is reflected. The value of momentum transferred to the surface is:

6.
Two small identical metallic balls having charges \( q \) and \( -2q \) are kept far at a separation \( r \). They are brought in contact and then separated at distance \( \frac{r}{2} \). Compared to the initial force \( F \), they will now: