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NCERT Solutions for Class 9 Science Chapter 11 Work Power and Energy
NCERT Solutions for Class 9 Science Chapter 11 Work Power and Energy are prepared by CBSE student eCARE expert to score good marks in class 9. This chapter contain many topics which are very important to score good in class 9. There are some important topic/Activity mentioned below-
Topics and Sub Topics in Class 9 Science Chapter 11 Work Power and Energy:
- Work Power and Energy
- Work
- Energy
- Rate of Doing Work
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Some questions are asked by class 9 students related to Science
Q1. When do we say that work is done?
Work is said to be done when a force causes displacement of an object in the direction of applied force.
Q2. Write an expression for the work done when a force is acting on an object in the direction of its displacement.
Work done = Force x Displacement
Q3. Define 1J of work.
When a force of IN causes a displacement of 1m, in its own direction the work done is said to be one joule.
Q4. 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?
Work done = Force x Displacement = 140 x 15 = 2,100 J
Q. What is power?
Power is defined as the rate of doing work
Q. Define 1 watt of power.
When a work of 1 joule is done in 1 s, the power is said to be one watt.
Q. A lamp consumes 1000 J of electrical energy in 10 s. What is its power?
Given W = 1000J, t = 10s, P =?
We know, P = W/t = 1000/10 = 100W
Q. Define average power.
When a machine or person does different amounts of work or uses energy in different intervals of time, the ratio between the total work or energy consumed to the total time is average power.