NCERT Solutions for Class 11 Physics Chapter 6 - Work, Energy and PowerShare
Refer to Goprep’s NCERT Solutions for Class 11 Physics Chapter 6 – Work, Energy and Power to prepare for the Physics exam in the most efficient manner. These Solutions for the Chapter 6 can help you practice different types of questions and asses the level of your Physics exam preparation. By referring to our NCERT Solutions for Chapter 6 - Work, Energy and Power, you can get access to easy and detailed answers to the questions of your Physics textbook.
Further, our NCERT Solutions comprise of answers to short answer types questions, MCQ’s as well as Exemplar problems. So, by incorporating these NCERT Solutions into your Physics exam preparation, you can clear your doubts and develop your question-solving skills to perform better in the Class 11 Physics exam.
Given below are the topics discussed in NCERT Solutions for Physics Class 11 Chapter - Work, Energy and Power –
- Introduction to the concept of work done by a body
- Notions of work and kinetic energy: The work-energy theorem
- Kinetic energy
- Work Done by a variable force
- The work-energy theorem for a variable force
- The concept of potential energy
- The conservation of mechanical energy
- The potential energy of a spring
- Various forms of energy: the law of conservation of energy
NCERT Solutions for Class 11 Physics Chapter 6 - Work, Energy and Power
The sign of work done by a force on a body is important to understand. State carefully if the following quantities are positive or negative:
A. work done by a man in lifting a bucket out of a well by means of a rope tied to the bucket.
B. work done by gravitational force in the above case,
C. work done by friction on a body sliding down an inclined plane,
D. work done by an applied force on a body moving on a rough horizontal plane with uniform velocity,
E. work done by the resistive force of air on a vibrating pendulum in bringing it to rest.
A body of mass 2 kg initially at rest moves under the action of an applied horizontal force of 7 N on a table with coefficient of kinetic friction = 0.1. Compute the
A. work done by the applied force in 10 s,
B. work done by friction in 10 s,
C. work done by the net force on the body in 10 s,
D. change in kinetic energy of the body in 10 s, and interpret your results.
Given in Fig. 6.11 are examples of some potential energy functions in one dimension. The total energy of the particle is indicated by a cross on the ordinate axis. In each case, specify the regions, if any, in which the particle cannot be found for the given energy. Also, indicate the minimum total energy the particle must have in each case. Think of simple physical contexts for which these potential energy shapes are relevant.
The potential energy function for a particle executing linear simple harmonic motion is given by V(x) = kx2/2, where k is the force constant of the oscillator. For k = 0.5 N m-1, the graph of V(x) versus x is shown in Fig. 6.12. Show that a particle of total energy 1 J moving under this potential must ‘turn back’ when it reaches x = � 2 m.
Answer the following:
A. The casing of a rocket in flight burns up due to friction. At whose expense is the heat energy required for burning obtained? The rocket or the atmosphere?
B. Comets move around the sun in highly elliptical orbits. The gravitational force on the comet due to the sun is not normal to the comet’s velocity in general. Yet the work done by the gravitational force over every complete orbit of the comet is zero. Why?
C. An artificial satellite orbiting the earth in very thin atmosphere loses its energy gradually due to dissipation against atmospheric resistance, however small. Why then does its speed increase progressively as it comes closer and closer to the earth?
D. In Fig. 6.13(i) the man walks 2 m carrying a mass of 15 kg on his hands. In Fig. 6.13(ii), he walks the same distance pulling the rope behind him. The rope goes over a pulley, and a mass of 15 kg hangs at its other end. In which case is the work done greater?
Underline the correct alternative:
A. When a conservative force does positive work on a body, the potential energy of the body increases/decreases/remains unaltered.
B. Work done by a body against friction always results in a loss of its kinetic/potential energy.
C. The rate of change of total momentum of a many-particle system is proportional to the external force/sum of the internal forces on the system.
D. In an inelastic collision of two bodies, the quantities which do not change after the collision are the total kinetic energy/total linear momentum/total energy of the system of two bodies.
State if each of the following statements is true or false. Give reasons for your answer.
A. In an elastic collision of two bodies, the momentum and energy of each body is conserved.
B. Total energy of a system is always conserved, no matter what internal and external forces on the body are present.
C. Work done in the motion of a body over a closed loop is zero for every force in nature.
D. In an inelastic collision, the final kinetic energy is always less than the initial kinetic energy of the system.
Answer carefully, with reasons:
A. In an elastic collision of two billiard balls, is the total kinetic energy conserved during the short time of collision of the balls (i.e. when they are in contact)?
B. Is the total linear momentum conserved during the short time of an elastic collision of two balls?
C. What are the answers to (a) and (b) for an inelastic collision?
D. the potential energy of two billiard balls depends only on the separation distance between their centres, is the collision elastic or inelastic? (Note, we are talking here of potential energy corresponding to the force during collision, not gravitational potential energy).
|Chapter 1 - Physical World|
|Chapter 2 - Units and Measurements|
|Chapter 3 - Motion in a Straight Line|
|Chapter 4 - Motion in a Plane|
|Chapter 5 - Laws of Motion|
|Chapter 6 - Work, Energy and Power|
|Chapter 7 - System of Particles and Rotational Motion|
|Chapter 8 - Gravitation|