Mechanics

Step 1: Understanding the conversion.
1 Newton is defined as dyne in the CGS system. This is the standard conversion factor.

Step 2: Conclusion.
Therefore, 1 Newton is equal to dyne.


Final Answer: .

Step 1: Understand the process.
When water falls from a height, its potential energy is converted into kinetic energy. Upon hitting the bottom, this kinetic energy is converted into heat energy due to friction and other factors. This heat raises the temperature of the water at the bottom of the waterfall.

Step 2: Conclusion.
Thus, the temperature at the bottom is higher due to the conversion of kinetic energy into heat.


Final Answer: The kinetic energy of the falling water is converted into heat.

Step 1: Understanding SONAR.
SONAR (Sound Navigation and Ranging) is a technique used to detect objects underwater by emitting sound waves and analyzing the reflected waves. The sound waves used in SONAR are typically high-frequency sound waves.

Step 2: Types of sound waves.
- These are sound waves that can be heard by humans, typically in the frequency range of 20 Hz to 20,000 Hz. They are not used in SONAR because they do not travel efficiently through water.
- Correct. Ultrasound waves are high-frequency sound waves above the range of human hearing, typically above 20 kHz. They are widely used in SONAR for their ability to travel long distances underwater.
- These are sound waves below the range of human hearing, below 20 Hz. They are not used in SONAR.
- These are electromagnetic waves, not sound waves, and are not used in SONAR.

Step 3: Conclusion.
The correct type of waves used in SONAR are ultrasound waves.

Final Answer: Ultrasound waves.