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 The physics of a raindrop is a fascinating topic that encompasses many different areas of science, including aerodynamics, fluid dynamics, and thermodynamics.

Shape

Raindrops are not perfectly spherical, but they are close. This is because of the force of surface tension, which is the attraction between water molecules at the surface of a droplet. Surface tension tends to minimize the surface area of a droplet, so it pulls the water molecules into a sphere.

However, as a raindrop falls, it also experiences air resistance. Air resistance is a force that opposes the motion of an object through the air. The larger the raindrop, the more air resistance it experiences.

As a raindrop falls faster, it also experiences more air resistance. This is because the air resistance force is proportional to the square of the velocity of the object.

At a certain point, the air resistance force on a raindrop becomes so large that it overcomes the surface tension force. This causes the raindrop to flatten out at the bottom and become more tear-shaped.

Speed

The speed of a raindrop depends on a number of factors, including its size, the air resistance it experiences, and the height from which it falls.

Small raindrops can fall at speeds of around 5 meters per second, while large raindrops can fall at speeds of up to 9 meters per second. The terminal velocity of a raindrop is the speed at which it falls when the air resistance force is equal to the force of gravity.

Energy

Raindrops contain kinetic energy, which is the energy of motion. The kinetic energy of a raindrop is proportional to the mass of the raindrop and the square of its velocity.

When a raindrop hits the ground, it releases its kinetic energy. This can cause damage to property and crops, especially during heavy rainstorms.

Pictures

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Opens in a new window www.sciencenews.org

Ten question test

1. What is the force that tends to minimize the surface area of a water droplet?

2. What is the force that opposes the motion of an object through the air?

3. What is the terminal velocity of a raindrop?

4. What type of energy does a raindrop contain?

5. What happens to the kinetic energy of a raindrop when it hits the ground?

6. Why are small raindrops more spherical than large raindrops?

7. What factors affect the speed of a raindrop?

8. What is the average mass of a raindrop?

9. What is the average terminal velocity of a raindrop?

10. How much kinetic energy does a raindrop have when it hits the ground if it has a mass of 0.05 grams and a velocity of 9 meters per second?

Answers

1. Surface tension
2. Air resistance
3. The terminal velocity of a raindrop is the speed at which it falls when the air resistance force is equal to the force of gravity.
4. Kinetic energy
5. When a raindrop hits the ground, it releases its kinetic energy. This can cause damage to property and crops, especially during heavy rainstorms.
6. Small raindrops are more spherical than large raindrops because the force of surface tension is more dominant in smaller droplets.
7. The speed of a raindrop depends on a number of factors, including its size, the air resistance it experiences, and the height from which it falls.
8. The average mass of a raindrop is about 0.05 grams.
9. The average terminal velocity of a raindrop is about 9 meters per second.
10. The kinetic energy of a raindrop with a mass of 0.05 grams and a velocity of 9 meters per second is about 0.225 joules.