Hovercraft B/C

[Ashernoel]

Hey guys,

I'm kinda new around here so please excuse me if I'm breaking some sort of rule(s) by butting in here, but I've got a question about a question I just saw on a Hovercraft test. The question reads:
"A pipe carrying water at 20°C has a diameter of 2.5 cm. Estimate the maximum flow speed if the flow must be streamline as measured in cm/sec."
Everywhere I've looked online has stated that in order to find the value of the velocity of the water in the pipe, the volume or mass flow rate is also required, but I don't see how you'd derive that from the information given. Am I missing something in this question, or is it just a bad question? Thanks!

LOL that's a wright state test question. lol 20/2.5 = 8 lol

lol

[megapanda]

Hey guys
I have some questions i hope you can answer for nationals

Do the airport security people cause any trouble with bringing your hovercraft as a carry on?
Do most teams have really precise, max weight hovercrafts? (how do you even make it that heavy )
Can we practice on the track the day before the actual event?
Are we allowed to touch the hovercraft before it crosses or drop runs to count them as failed runs?
Do we get test/practice runs during our 8 mins?


Thanks so much!

[windu34]

Hey guys
I have some questions i hope you can answer for nationals

Do the airport security people cause any trouble with bringing your hovercraft as a carry on?
Do most teams have really precise, max weight hovercrafts? (how do you even make it that heavy )
Can we practice on the track the day before the actual event?
Are we allowed to touch the hovercraft before it crosses or drop runs to count them as failed runs?
Do we get test/practice runs during our 8 mins?


Thanks so much!

1.) Um YES! Do not risk it! "Don't worry its not a bomb" wont fly here
2.) Id say at least 1/3 (so 20 teams) will have max weight hovercrafts. Idk about how precise people will be. I'm curious about predictions about this as well
3.) No I highly doubt that
4.) Someone else please answer this. I know there was discussion about this and now I cant remember. I feel like the answer is no
5.) No

[RestingDoll]

Hey guys,

I'm kinda new around here so please excuse me if I'm breaking some sort of rule(s) by butting in here, but I've got a question about a question I just saw on a Hovercraft test. The question reads:
"A pipe carrying water at 20°C has a diameter of 2.5 cm. Estimate the maximum flow speed if the flow must be streamline as measured in cm/sec."
Everywhere I've looked online has stated that in order to find the value of the velocity of the water in the pipe, the volume or mass flow rate is also required, but I don't see how you'd derive that from the information given. Am I missing something in this question, or is it just a bad question? Thanks!

LOL that's a wright state test question. lol 20/2.5 = 8 lol

lol

Uhh I think it's a bit more complicated lol.
Kinematic viscosity of water @20 C = 1.004e-6
Reynold's Number = velocity * diameter / viscosity
Streamlined Re = 2000 (This is interesting -- depending on the source it varies. 2000 gives you exactly 8.032 cm/s though.)
2000 = (v*.025)/(1.004e-6)
v=.8032 m/sec
v=8.032 cm/sec, sig fig ~~ 8.0 cm/sec

[ApprovedCargo91]

Uhh I think it's a bit more complicated lol.
Kinematic viscosity of water @20 C = 1.004e-6
Reynold's Number = velocity * diameter / viscosity
Streamlined Re = 2000 (This is interesting -- depending on the source it varies. 2000 gives you exactly 8.032 cm/s though.)
2000 = (v*.025)/(1.004e-6)
v=.8032 m/sec
v=8.032 cm/sec, sig fig ~~ 8.0 cm/sec

Woah, there's still much I don't know how to do apparently. Thanks for replying with the solution!

[Ashernoel]

Hey guys,

I'm kinda new around here so please excuse me if I'm breaking some sort of rule(s) by butting in here, but I've got a question about a question I just saw on a Hovercraft test. The question reads:
"A pipe carrying water at 20°C has a diameter of 2.5 cm. Estimate the maximum flow speed if the flow must be streamline as measured in cm/sec."
Everywhere I've looked online has stated that in order to find the value of the velocity of the water in the pipe, the volume or mass flow rate is also required, but I don't see how you'd derive that from the information given. Am I missing something in this question, or is it just a bad question? Thanks!

LOL that's a wright state test question. lol 20/2.5 = 8 lol

lol

Uhh I think it's a bit more complicated lol.
Kinematic viscosity of water @20 C = 1.004e-6
Reynold's Number = velocity * diameter / viscosity
Streamlined Re = 2000 (This is interesting -- depending on the source it varies. 2000 gives you exactly 8.032 cm/s though.)
2000 = (v*.025)/(1.004e-6)
v=.8032 m/sec
v=8.032 cm/sec, sig fig ~~ 8.0 cm/sec

ah that makes sense. lol. not 20/2.5 xD lolllll

[Zioly]

LOL that's a wright state test question. lol 20/2.5 = 8 lol

lol

Uhh I think it's a bit more complicated lol.
Kinematic viscosity of water @20 C = 1.004e-6
Reynold's Number = velocity * diameter / viscosity
Streamlined Re = 2000 (This is interesting -- depending on the source it varies. 2000 gives you exactly 8.032 cm/s though.)
2000 = (v*.025)/(1.004e-6)
v=.8032 m/sec
v=8.032 cm/sec, sig fig ~~ 8.0 cm/sec

ah that makes sense. lol. not 20/2.5 xD lolllll

I'm so glad Div. B doesn't have to deal with these problems (or so the rules say...).

[antoine_ego]

I'm sad that we cannot know who's writing the test for Div C, because they aren't releasing event supervisors. It was nice back in the day when you could actually get an idea of a test writer's style by figuring out what Invites they ran and getting ahold of those tests. Sad life

[Ionizer]

Didn't they write the tests for Golden Gate and MIT?

From the Nationals thread:

The Hovercraft ES also supervised at MIT and Golden Gate I believe

This is for div c

The hovercraft supervisor did not supervise at golden gate

I believe the tests were written by the same people at both Golden Gate and MIT though.

[antoine_ego]

Didn't they write the tests for Golden Gate and MIT?

From the Nationals thread:

The hovercraft supervisor did not supervise at golden gate

I believe the tests were written by the same people at both Golden Gate and MIT though.

I talked to the test writer at MIT. The official ES was a different guy from the test writer. The official one was also the one who brought in the tracks. We know he's going to be at Nats. However, we don't know if the MIT/Golden Gate test writer is the same guy writing at Nats.