NCERT Class 11 Physics Solutions: Chapter 6 – Work, Energy, and Power Part 5

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Question 6.9:

A body is initially at rest. It undergoes one-dimensional motion with constant acceleration. The power delivered to it at time t is proportional to



Mass of the body

Acceleration of the body

Using Newton’s second law of motion, the force experienced by the body is given by the equation:

Both and are constants. Hence, force F will also be a constant.

For velocity v, acceleration is given as,

Where is another constant

Power is given by the relation:

Using Equation and, We have:

Hence, Power is directly proportional to time.

Question 6.10:

A body is moving unidirectionally under the influence of a source of constant power. Its displacement in time is proportional to


Power is given by the relation:

Integrating both sides:

For displacement of the body, we have:


On integrating both sides, we get: