The temperature of water at the bottom of a waterfall is higher than that of the water at the top, because

Options

A. falling water absorbs heat from the sun
B. kinetic energy of the falling water is con verted into heat
C. water at the bottom has greater potential energy
D. the rocks on the river bed give out heat

Answer

To solve the question of why the temperature of water at the bottom of a waterfall is higher than that of the water at the top, we can analyze the situation step by step.

### Step-by-Step Solution:

1. **Understanding Potential Energy**:
- At the top of the waterfall, the water has a significant amount of potential energy due to its height. Potential energy (PE) is given by the formula:
\[ PE = mgh \]
where \( m \) is mass, \( g \) is the acceleration due to gravity, and \( h \) is the height.

2. **Water Falls Down**:
- As the water falls, its height decreases, which means its potential energy decreases.

3. **Conversion of Energy**:
- The potential energy that the water loses as it falls is converted into kinetic energy (KE). The kinetic energy of an object is given by the formula:
\[ KE = \frac{1}{2} mv^2 \]
where \( v \) is the velocity of the water.

4. **Increase in Kinetic Energy**:
- As the water continues to fall, its kinetic energy increases. This increase in kinetic energy is associated with an increase in the motion of water molecules.

5. **Conversion to Heat**:
- When the water reaches the bottom of the waterfall, the kinetic energy of the water is converted into heat energy due to the impact and turbulence as it hits the surface below. This increase in kinetic energy results in a rise in temperature.

6. **Conclusion**:
- Therefore, the temperature of the water at the bottom of the waterfall is higher than that at the top because the kinetic energy of the falling water is converted into heat energy.

### Final Answer:
The correct explanation is that the kinetic energy of the falling water is converted into heat, resulting in a higher temperature at the bottom of the waterfall.

---