Hovercraft B/C

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photolithoautotroph
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Re: Hovercraft B/C

Postby photolithoautotroph » April 19th, 2018, 12:39 pm

Consider a pipe with radius r.

If an ideal fluid is flowing through the pipe, how would the flow rate change if the radius was increased to 2r?

If a non-ideal, viscous fluid is flowing through the pipe, how would the flow rate change if the radius was increased to 2r?
Both fluids would go through twice as slowly?
I haven't done enough fluid dynamics to be sure, but I can guess: for an ideal fluid the flow rate would change to 4Q (Q=Av) and for a non-ideal, viscous fluid, the flow rate would change to 16Q (Poiseuille's Law)? Less sure about the second one but either could be wrong. At least I don't actually have to do this for real.
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Re: Hovercraft B/C

Postby Tesel » April 19th, 2018, 7:52 pm

Consider a pipe with radius r.

If an ideal fluid is flowing through the pipe, how would the flow rate change if the radius was increased to 2r?

If a non-ideal, viscous fluid is flowing through the pipe, how would the flow rate change if the radius was increased to 2r?
Both fluids would go through twice as slowly?
I haven't done enough fluid dynamics to be sure, but I can guess: for an ideal fluid the flow rate would change to 4Q (Q=Av) and for a non-ideal, viscous fluid, the flow rate would change to 16Q (Poiseuille's Law)? Less sure about the second one but either could be wrong. At least I don't actually have to do this for real.
I should have clarified the question a lot better.
But yes, you made the right assumptions, and that was the correct use of Poiseuille's Law. Correct!
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Re: Hovercraft B/C

Postby CMS AC » May 1st, 2018, 10:19 am

Consider a pipe with radius r.

If an ideal fluid is flowing through the pipe, how would the flow rate change if the radius was increased to 2r?

If a non-ideal, viscous fluid is flowing through the pipe, how would the flow rate change if the radius was increased to 2r?
Both fluids would go through twice as slowly?
I haven't done enough fluid dynamics to be sure, but I can guess: for an ideal fluid the flow rate would change to 4Q (Q=Av) and for a non-ideal, viscous fluid, the flow rate would change to 16Q (Poiseuille's Law)? Less sure about the second one but either could be wrong. At least I don't actually have to do this for real.
Next question, please.

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Re: Hovercraft B/C

Postby photolithoautotroph » May 3rd, 2018, 4:19 pm

If nobody posts a question in this long, you can.
Derive a formula for the acceleration of the blocks in a real atwood machine with two masses of mass [math]m1[/math] and [math]m2[/math]and a pulley in the shape of a uniform disk of mass [math]M[/math] and radius [math]r[/math]. The string is massless. Ignore friction.
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Re: Hovercraft B/C

Postby IvanGe » May 3rd, 2018, 4:51 pm

If nobody posts a question in this long, you can.
Derive a formula for the acceleration of the blocks in a real atwood machine with two masses of mass [math]m1[/math] and [math]m2[/math]and a pulley in the shape of a uniform disk of mass [math]M[/math] and radius [math]r[/math]. The string is massless. Ignore friction.
a = m1g - m2g / m1+ m2
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UTF-8 U+6211 U+662F
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Re: Hovercraft B/C

Postby UTF-8 U+6211 U+662F » May 3rd, 2018, 4:57 pm

If nobody posts a question in this long, you can.
Derive a formula for the acceleration of the blocks in a real atwood machine with two masses of mass [math]m1[/math] and [math]m2[/math]and a pulley in the shape of a uniform disk of mass [math]M[/math] and radius [math]r[/math]. The string is massless. Ignore friction.
The acceleration of m1 where positive is down is 
EDIT: Whoops, didn't see other answer

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Re: Hovercraft B/C

Postby PW240.3 » May 7th, 2018, 2:35 pm

If nobody posts a question in this long, you can.
Derive a formula for the acceleration of the blocks in a real atwood machine with two masses of mass [math]m1[/math] and [math]m2[/math]and a pulley in the shape of a uniform disk of mass [math]M[/math] and radius [math]r[/math]. The string is massless. Ignore friction.

Since you have to account for the pulley's moment of inertia, wouldn't the a be a=(m1-m2)g/(m1+m2+M/4)

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Re: Hovercraft B/C

Postby IvanGe » May 7th, 2018, 6:18 pm

I'm just going to ask a question because no one's verified the answer.

With what constant velocity can a 4.00 hp motor raise a mass of 125 kg?
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nats '19:
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Re: Hovercraft B/C

Postby Adi1008 » May 7th, 2018, 10:31 pm

I'm just going to ask a question because no one's verified the answer.

With what constant velocity can a 4.00 hp motor raise a mass of 125 kg?
2.43 meters per second
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IvanGe
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Re: Hovercraft B/C

Postby IvanGe » May 8th, 2018, 5:36 am

I'm just going to ask a question because no one's verified the answer.

With what constant velocity can a 4.00 hp motor raise a mass of 125 kg?
2.43 meters per second

that's what i got, but the answer key said 2.76 m/s?

Anyways, your turn
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nats '19:
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