NCERT Solutions for Class 9 Science Chapter 11 – Work and Energy. Furthermore, here we’ve provided you with the latest solution for Class 9 Science Chapter 11 – Work and Energy. As a result here you’ll find solutions to all the exercises. This NCERT Class 9 solution will help you to score good marks in your exam.
Students can refer to our solution for NCERT Class 9 Science Chapter 11 – Work and Energy. The Chapter 11 Solution of NCERT will help students prepare for the exams and easily crack the exam. Below we’ve provided you with the latest solution.
NCERT Solutions for Class 9 Science Chapter 11 – Work and Energy
Question 1: A force of 7 N acts on an object. The displacement is, say 8 m, in the direction of the force (Fig. 11.3). Let us take it that the force acts on the object through the displacement. What is the work done in this case?
Answer: When a force F acts on an object to displace it through a distance S in its direction, then the work done W on the body by the force is given by:
Work done = Force × Displacement W = F × S
Where, F = 7 N S = 8 m
Therefore, work done, W = 7 × 8
= 56 Nm
= 56 J
Question 1: When do we say that work is done?
Answer: Work is done whenever the given conditions are satisfied:
- A force acts on the body.
- There is a displacement of the body caused by the applied force along the direction of the applied force.
Question 2: Write an expression for the work done when a force is acting on an object in the direction of its displacement.
Answer: When a force F displaces a body through a distance S in the direction of the applied force, then the work done W on the body is given by the expression:
Work done = Force × Displacement W = F × s
Question 3: Define 1 J of work.
Answer: 1 J is the amount of work done by a force of 1 N on an object that displaces it through a distance of 1 m in the direction of the applied force.
Question 4: A pair of bullocks exerts a force of 140 N on a plough. The field being ploughed is 15 m long. How much work is done in ploughing the length of the field?
Answer: Work done by the bullocks is given by the expression: Work done = Force × Displacement
W = F × d
Where,
Applied force, F = 140 N Displacement, d = 15m.
NCERT Class 9 Science All Chapters Solution
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: Fundamental Unit of Life
Chapter 6: Tissues
Chapter 7: Diversity in Living Organisms
Chapter 8: Motion
Chapter 9: Force and Laws of Motion
Chapter 10: Gravitation
Chapter 11: Work and Energy
Chapter 12: Sound
Chapter 13: Why Do We Fall Ill
Chapter 14: Natural Resources
Chapter 15: Improvement in Food Resources