# NCERT Class 9 Science Solutions: Chapter 11 – Work and Energy Part 3

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Question 1:

Q. What is Power?

Answer:

Power is the rate of doing work or the rate of transfer of energy. If is the amount of work done in time then power is given by the expression,

It is expressed in watt

Question 2:

Q. Define 1 watt of power:

**Answer:**

A body is said to have power of watt if it does work at the rate of joule in,

i.e.

Question 3:

Q. A lamp consumes of electrical energy in what is its power?

**Answer:**

Power is given by the expression,

Question 4:

Q. Define average power.

Answer:

A body can do different amount of work in different time intervals. Hence, it is better to define average power. Average power is obtained by dividing the total amount of work done in the total time taken to do work.

Average Power