# NCERT Class-9 Science Solutions: Chapter 11-Work and Energy Part 2

Question 8:

Water stored in a dam possesses

1. No energy

2. Electrical energy

3. Kinetic energy

4. Potential energy

Question 9:

A body is falling from a height. After it has fallen a height, it will possess

1. Only potential energy

2. Only kinetic energy

3. Half potential and half kinetic energy

4. More kinetic and less potential energy

Question 10:

A rocket is moving up with a velocity. If the velocity of this rocket is suddenly tripled, what will be the ratio of two kinetic energies?

Initial velocity

Initial kinetic energy

Final kinetic energy (K.E.)

Question 11:

Avinash can run with a speed of against the frictional force of, and Kapil can move with a speed of against the frictional force of. Who is more powerful and why?

Given, force applied by Avinash = 10 N

Speed of Avinash = 8 ms-1 ‘

Power of Avinash

Now, force applied by Kapil

Speed of Kapil

The power of Kapil

Since, Avinash has more power W than Kapil. Therefore, Avinash is more powerful.

Question 12:

A boy is moving on a straight road against a frictional force of . After travelling a distance of he forgot the correct path at a roundabout (Figure) of radius . However, he moves on the circular path for one and half cycle and then he moves forward up to . calculate the work done by him.