Quick physics question

[NuclearFusi0n]

Raindrops fall 1700 m, not taking into account air resistance, how fast are they when the hit the ground
i came up with 182.5 m/s

"would it be safe to walk outside during a rainstorm?"

hmmm, what should i put for that question? rather subjective, no?

 

[Viper GTS]

Compare it to bullets. You can easily determine the muzzle velocity & mass of a common bullet (ie .22), & the average mass of a raindrop shouldn't be too hard to figure out either.

With mass & velocity kinetic energy is simple...

Viper GTS

 

[DivideBYZero]

In continental clouds, most droplets are smaller than one seven hundredths of an inch in diameter, and have fall speeds of less than 2 feet per second. It would take such a drop 45 minutes to fall from a height of a mile, so a large number of cloud droplets must join together to make a raindrop large enough to fall fast enough to reach the ground before it evaporates.

Raindrop speed link

 

[DivideBYZero]

DAMN! why did my eyes skip the air resistance part?

 

[brunswickite]

I would say yes it is safe, there surface area is too small for it be dangerous?


like if it was a hail storm i would say it would be dangerous becasue of the large surface area.

 

[Viper GTS]

Originally posted by: brunswickite
I would say yes it is safe, there surface area is too small for it be dangerous?


like if it was a hail storm i would say it would be dangerous becasue of the large surface area.

Watch out for bubbles, they're a killer.

Viper GTS

 

[Beau]

Originally posted by: Viper GTS

Originally posted by: brunswickite
I would say yes it is safe, there surface area is too small for it be dangerous?


like if it was a hail storm i would say it would be dangerous becasue of the large surface area.

Watch out for bubbles, they're a killer.

Viper GTS

😀 lol!!!

 

[NuclearFusi0n]

Originally posted by: Viper GTS

Originally posted by: brunswickite
I would say yes it is safe, there surface area is too small for it be dangerous?


like if it was a hail storm i would say it would be dangerous becasue of the large surface area.

Watch out for bubbles, they're a killer.

Viper GTS

bauhahahaha!

 

[Yossarian]

It's a kinetic energy question. I would just use 1 cm^3 as the volume of a raindrop. ke=.5mv^2, so the energy of a raindrop is 16.7 J. That's like getting hit with a 1-kg brick moving at 9MPH so it's probably not pleasant.

 

[RSMemphis]

I come up with 182 m/s as well.

And it would be the same as lead drops falling. Definitely not a good idea to walk in that thunderstorm (although - without air resistance, a thunderstorm isn't so deadly. LOL)

 

[DivideBYZero]

Originally posted by: PipBoy
It's a kinetic energy question. I would just use 1 cm^3 as the volume of a raindrop. ke=.5mv^2, so the energy of a raindrop is 16.7 J. That's like getting hit with a 1-kg brick moving at 9MPH so it's probably not pleasant.

Ooooh, scary bag of sugar moving at........9Mph, LMAO

 

[Yossarian]

ok it's a small brick 🙂 but getting hit with dozens of them every second wouldn't be much fun.

 

[Armitage]

Assume a raindrop has a mass of 5g

KE = 0.5 m v^2 = 0.5*0.005 * 182.5^2 = 83.2656 kg m^2/s^2 (joules)

Assume a 2Kg brick (about 5 lbs)

Equating potential energy to kinetic energy...
PE = m g h

h = PE/(m g)

h = 83.2656/(2 * 9.8)

h = 4.248 m = 13.9 feet

So, this raindrop would hit you with the energy of a brick dropped from 14 feet up. The energy would be concentrated over a much smaller area. I'd stay out of the rain!

edit: pipboy assumed a 1 gram raindrop. Usingf that in my analysis gives you a 2Kg brick dropped from 2.8 ft up. Say from your waist to your toes. Still not fun.