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#### zzzZZZSSSsss

• Guest
##### Noob Question, die for answer
« on: May 21, 2009, 23:09:59 PM »
Good morning from Karditsa.

Here is my question:

What is the maximum speed of rain?

we have bet with friends. I say 50Km/h, he say up of 100 Km/h. If anyone now answer please answer.

Good morning

#### kam

• Hero Member
• Posts: 1849
##### Re: Noob Question, die for answer
« Reply #1 on: May 21, 2009, 23:49:29 PM »
i googled for fun and found more than a million topics declaring that rain falls from 6 to 7 meter per sec, something between and 21 and 25km/h.

You won the bet

Celebrate

#### spic0m

• Global Moderator
• Hero Member
• Posts: 841
##### Re: Noob Question, die for answer
« Reply #2 on: May 21, 2009, 23:56:21 PM »
Raindrops typically hit the ground at velocities of around a meter per second. Since the raindrop usually falls from a cloud at a height of at least one kilometer, it must fall for many minutes before reaching the ground. Thus it has lots of time to reach terminal velocity. The terminal velocity depends on the size of the raindrop, being larger for larger raindrops. This is because the terminal velocity results from a balance between the force of gravity and the aerodynamic drag force. The gravitational force is proportional to the mass of the drop, and therefore its volume. The aerodynamic drag is proportional to the radius times the velocity. (This is called Stokes' Law.) Fog consists of very small drops, which fall at speeds of less than a meter per minute. A large hailstone can reach a velocity of several tens of meters per second, and thus can cause considerable damage when it hits the ground!

From Washington University papers.

#### zzzZZZSSSsss

• Guest
##### Re: Noob Question, die for answer
« Reply #3 on: May 23, 2009, 19:02:27 PM »
Is it 1 or 7 ?

#### spic0m

• Global Moderator
• Hero Member
• Posts: 841
##### Re: Noob Question, die for answer
« Reply #4 on: May 23, 2009, 23:17:13 PM »
No matter what it is, you won the bet.
Probably has to do with the size of raindrop.