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by mjcox2000
April 22nd, 2019, 12:32 pm
Forum: 2019 Question Marathons
Topic: Thermodynamics B/C
Replies: 127
Views: 12218

Re: Thermodynamics B/C

I'm confused how the reservoirs could reach equilibrium? The Carnot cycle assumes that the reservoirs will never change temperature. The Carnot cycle doesn’t require constant-temperature reservoirs. Hint|The Carnot efficiency equation predicts the instantaneous efficiency. Try integrating. Answers ...
by mjcox2000
April 16th, 2019, 3:11 am
Forum: 2019 Question Marathons
Topic: Thermodynamics B/C
Replies: 127
Views: 12218

Re: Thermodynamics B/C

A hot and cold reservoir are used to convert heat to work in a Carnot cycle. The hot reservoir starts at 400K and has a heat capacity of 40 J/K, and the cold reservoir starts at 100K and has a heat capacity of 20 J/K. The Carnot cycle runs until the reservoirs are in thermal equilibrium. 1. At what...
by mjcox2000
April 16th, 2019, 3:05 am
Forum: 2019 Question Marathons
Topic: Sounds Of Music C
Replies: 120
Views: 13928

Re: Sounds Of Music C

It could also be|an issue with the resonators, so she could check to see if the buzzing is still heard when the resonator is blocked. Yes|If it’s a screw rattling on the resonators, it will likely rattle for multiple notes, not just the one. But if it’s a loose resonator cap or an object inside the...
by mjcox2000
April 1st, 2019, 4:13 am
Forum: 2019 Question Marathons
Topic: Sounds Of Music C
Replies: 120
Views: 13928

Re: Sounds Of Music C

Answer|The key could be touching a support and vibrating against it or the chord going through the keys could be too lose (although I think that would affect other keys as well so it's more likely the first issue). Sort of|Having the bar touch a support could certainly be the reason it’s buzzing. (...
by mjcox2000
March 31st, 2019, 8:31 pm
Forum: 2019 Question Marathons
Topic: Sounds Of Music C
Replies: 120
Views: 13928

Re: Sounds Of Music C

Anna hears a buzzing sound when she plays a low C on her marimba, but not when she plays other notes. What are some things she should check to figure out what’s causing the buzzing sound? Answer|The key could be touching a support and vibrating against it or the chord going through the keys could b...
by mjcox2000
March 28th, 2019, 7:26 am
Forum: 2019 Question Marathons
Topic: Sounds Of Music C
Replies: 120
Views: 13928

Re: Sounds Of Music C

Anna hears a buzzing sound when she plays a low C on her marimba, but not when she plays other notes. What are some things she should check to figure out what’s causing the buzzing sound?
by mjcox2000
March 25th, 2019, 6:23 am
Forum: 2019 Question Marathons
Topic: Sounds Of Music C
Replies: 120
Views: 13928

Re: Sounds Of Music C

You have purchased a slide whistle that is 30 cm from the lip to the slide when it is pulled all the way out. 1. What frequency does it play in this position? 2. How far should you move the slide up in order to play A4? 3. Approximately what frequency would the whistle play if the slide is removed?...
by mjcox2000
March 23rd, 2019, 12:42 pm
Forum: Mission Possible C
Topic: Endothermic Task
Replies: 60
Views: 8110

Re: Endothermic Task

We're trying to use a peltier cooler and thermistor in a circuit like the one attached, but we're having problems with calibrating the switching temperature. Is anyone else using something similar and have you had problems with re-calibrating at competition? http://www.learningaboutelectronics.com/...
by mjcox2000
March 14th, 2019, 6:45 pm
Forum: 2019 Question Marathons
Topic: Circuit Lab B/C
Replies: 154
Views: 14011

Re: Circuit Lab B/C

What are the values of R3 and R4 if you want the battery to supply 83.3 mA to the circuit while the ammeter reads 0.00mA? Image: https://drive.google.com/open?id=1_cVQzrlTEcn5QR0MSS49hMGLcoC9kaRg Answer|The 0 current condition requires that [math]\frac{R_3}{R_4}=\frac{20}{280}[/math], and the 83.3m...
by mjcox2000
March 14th, 2019, 4:16 am
Forum: 2019 Question Marathons
Topic: Thermodynamics B/C
Replies: 127
Views: 12218

Re: Thermodynamics B/C

A hot and cold reservoir are used to convert heat to work in a Carnot cycle. The hot reservoir starts at 400K and has a heat capacity of 40 J/K, and the cold reservoir starts at 100K and has a heat capacity of 20 J/K. The Carnot cycle runs until the reservoirs are in thermal equilibrium. 1. At what...

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